- What is it? CBD (cannabidiol) is a compound derived from hemp and marketed as a supplement despite the U.S. FDA’s position that CBD is not a dietary supplement.
- Does it work? CBD has been shown to reduce the frequency of certain types of seizures, and preliminary evidence suggests it may also help with anxiety, schizophrenia, and other conditions. However, all of these effects have involved large doses of CBD — hundreds of milligrams per day, which is more than in many marketed CBD supplements and products.
- What did CL find? ConsumerLab found the dose of CBD per suggested serving ranged 10-fold from 2.2 mg to 22.3 mg, and the cost to obtain 10 mg of CBD from each product ranged over 5-fold from 80 cents to $4.54.
- Top Picks — ConsumerLab selected a Top Pick for People and a Top Pick for Pets based on top quality and value.
- What to look for? If you seek CBD, look for products that list the amount of CBD per serving. If a product lists only “cannabinoids” it may contain some CBD but you won’t know how much. Products may still have significant amounts of CBD if they list “hemp extract” as an ingredient, but don’t expect much CBD if “hemp oil” is the only ingredient.
- How much to take and when? Most of the research with CBD has involved high doses (several hundred milligrams daily). However, many CBD products on the market are lower dose and it is not clear if this dosing is effective. Nevertheless, to greatly increase CBD absorption, take it with or shortly after a fatty meal. (See ConsumerTips: Dosage)
- Other concerns: High-dose CBD can cause a range of side effects (particularly gastrointestinal) and affect certain medications. For details, see Concerns and Cautions.
CBD Oil and Supplements with CL Founder, Dr. Tod Cooperman
What It Is:
Cannabidiol (CBD) and its precursor compound CBDa are dominant “cannabinoid” compounds found in hemp and cannabis (a hemp plant also known as marijuana). Unlike tetrahydrocannabinol (THC), which is another cannabinoid compound, CBD is not believed to be a psychoactive compound affecting perception and behavior.
What It Does:
NOTE: The effects described below are primarily based on daily doses of hundreds of milligrams of CBD. Many CBD products on the market contain much lower amounts (providing tens of milligrams or less per day), and it is not known if these low doses are as effective as higher doses.
Much of the research with CBD has focused on the reduction of certain types of seizures. A placebo-controlled clinical trial found a high daily dose of CBD (20 mg per kg of body weight, i.e., hundreds of milligrams) to reduce the frequency of convulsions in a rare form of epilepsyknown as Dravet syndrome in children and young adults, although it was also associated with a higher rate of adverse effects including diarrhea, vomiting, fatigue, pyrexia, somnolence, and abnormal results on liver-function tests (Devinsky, New Eng J Med 2017).
Similarly, the same high daily dose reduced the number of drop seizures among people with treatment-resistant Lennox-Gastaut syndrome in a 3-month study. Seizures per month decreased 44% with CBD compared to 22% with placebo; however, again, those taking CBD also had a higher rate of adverse effects including diarrhea, somnolence, fever, decreased appetite, and vomiting (Thiele, Lancet 2018). A study in Nashville among 108 children with refractory epilepsy who had been treated with commercially marketed CBD preparations found that CBD could be as effective as the anticonvulsant drug clobazam when used as add-on therapy.
A reduction in seizure activity of at least 50% occured in 33%, 38%, and 44% of those who received, respectively, CBD, clobazam, and CBD+clobazam. Relative to clobazam, CBD seemed to increase alertness and increase verbal interactions. Sedation, which was common among those taking clobazam, did not occur among those taking only CBD. The average daily dose was about 3 mg of CBD per kilogram of body weight: e.g., 100 mg per day for a 73 lb child. (Porcari, Epilepsy & Behav 2018).
A preliminary trial found modest, dose-related improvements in symptoms of dystonia (involuntary muscle contractions) in five individuals taking between 100 mg and 500 mg per day of cannabidiol; however, there was a worsening of tremor and the ability to initiate movement in two of the individuals who also had Parkinson’s disease (Consroe, Int J Neurosci 1986).
Results in people with schizophrenia have been mixed. A study of high-dose CBD (500 mg taken morning and evening) among adults with schizophrenia found that adding CBD rather than placebo to existing treatments for six weeks reduced psychotic symptoms and caused a trend, although not statistically significant, toward improved performance on cognitive tasks. In this study, CBD was well tolerated with no increase in adverse effects (McGuire, Am J Psy 2017). Another 6-week study, however, found that 300 mg of CBD taken twice daily did not improve cognitive or psychotic symptoms in adults with schizophrenia on stable doses of medication; in fact, only those taking a placebo experienced a (modest) improvement in symptoms. Twenty percent of CBD-treated patients experienced sedation (mostly mild) compared to 5% of those on placebo (Boggs, Psychopharm 2018).
CBD seems to “partially normalize alterations” in areas of the brain that are implicated in psychosis (i.e., severely impaired thoughts and/or emotions). This was shown in a small, placebo-controlled study that measured activation of areas of the brain (based on blood flow measured with MRI imaging) during a verbal learning task. Brain activity in people at high risk of psychosis given a single dose of 600 mg of CBD more closely resembled that of people not at risk of psychosis than of people at risk of psychosis who were given a placebo. Interestingly, THC in marijuana can have the opposite effect and has been associated with the development and relapse of psychosis (Bhattacharyya, JAMA Psych 2018).
Although laboratory studies and studies in animals suggest CBD may help reduce anxiety, there are only a few studies investigating these effects in people. For example, a small study in young healthy men found that a single, 400 mg dose of CBD taken as a capsule reduced self-reported anxiety (but also increased feelings of mental sedation), one hour after ingestion, compared to placebo (Crippa, Neuropsychopharmacology 2004). A study that found CBD reduced anxiety with social speaking utilized a single dose of 600 mg of CBD given 90 minutes before speaking (Bergamaschi, Neuropsychopharm 2011) and a similar study showed reduced anxiety using a dose of 300 mg (Zuardi, J Psychopharmacol 1993).
In a 10 year old girl with anxiety and sleep disorders due to post traumatic stress disorder (PTSD) caused by sexual abuse, 25 mg of CBD taken at bedtime, and 6 mg to 12 mg of CBD sublingual spray taken as needed throughout the day for 5 months improved her anxiety and sleep to the extent that they were no longer classified as disorders (Shannon, Perm J 2016). Although no side effects were observed, it is important to note that there is concern that cannabinoids may affect brain development in children (See Concerns and Cautions).
Preliminary research suggests that CBD may affect the sleep-wake cycle, although this may depend on the dose and the condition for which it is taken. Low-dose CBD (15 mg) may have a stimulating effect, while moderate and higher doses can be sedating, and may improve sleep in people with anxiety (as in the case report above) and in those with certain sleep disorders (Babson, Curr Psychiatry Rep 2017). For example, a small study among 15 men and women with a history of insomnia found that 160 mg of CBD taken as a capsule 30 minutes before bedtime for one week significantly increased self-reported duration of sleep compared to placebo.
Ten participants reported sleeping more than 7 hours after taking this dose of CBD, but when the same participants took a placebo, only six reported getting more than 7 hours of sleep. However, there was no decrease in the amount of time it took to fall asleep. Lower doses of CBD (40 mg and 80 mg) did not increase sleep time or reduce the amount of time it took to fall asleep (Carlini, J Clin Pharmacol 1981). None of the participants reported increased difficulty in waking or feeling sleepy upon awakening, compared to placebo.
In three older men with Parkinson’s disease and REM sleep behavior disorder (RBD) (characterized by intense dreams and behavior such as laughing, yelling, kicking and punching during sleep) who experienced disruptive sleep episodes between two and seven times per week, none experienced these symptoms during a six-week period of daily dosing with 75 mg of CBD. A fourth man, who took 300 mg of CBD daily for the same time period had a reduction in episodes from two to four times per week to once per week (Chagas, J Clin Pharm Ther 2014).
CBD did not seem to affect sleep in a study of 27 healthy men and women (average age 30) who did not have sleep or psychiatric disorders: A single 300 mg dose of CBD taken 30 minutes before bedtime had no effect on the time it took to fall asleep, the amount of time spent in each stage of sleep (such as REM sleep), or the amount of time participants stayed asleep (as measured by polysomnography), and it did not affect self-reported sleep quality, compared to placebo. CBD was not found to impair cognitive function when evaluated the following morning (Linares, Front Pharmacol 2018).
Although there is some preliminary evidence that THC and, possibly other cannabinoids could potentially help to reduce interocular (eye) pressure in people with glaucoma, one study found that, four hours after ingestion, a single, sublingual dose of CBD (which also contained about 1 mg of THC) had no effect on interocular pressure, while a 40 mg dose of CBD (containing about 2 mg of THC) temporarily increased interocular pressure (Tomida, J Glaucoma 2006; Health Canada 2013). There do not appear to be longer-term studies, or studies investigating the effects of cannabidiol alone for glaucoma.
One study found that an oral spray containing THC and CBD reduced pain in people with rheumatoid arthritis (Blake, Rheumatology (Oxford) 2006); however, a review of four short term clinical studies (including this one) investigating the effects of cannabinoids for the treatment of rheumatic diseases, including fibromyalgia syndrome, back pain, osteoarthritis and rheumatoid arthritis, concluded that there is “currently insufficient evidence to recommend cannabinoid treatments for management of rheumatic diseases pending further study.” (Fitzcharles, Schmerz 2016). There do not appear to be any studies on the use of CBD alone for reducing pain in these conditions.
A review of several experimental pain studies (using heat or pressure) on healthy people found that cannabis (marijuana) and cannabinoids may not reduce the intensity of pain, but may make pain feel less unpleasant and more tolerable. Although none of the studies tested CBD exclusively, the products containing CBD (in addition to THC), such as cannabis extracts, were shown to be more effective than those containing exclusively THC or THC analogues. The researchers suggested that CBD be investigated in future pain studies (De Vita, JAMA Psych 2018).
A few studies suggest that a combination of THC and CBD may be helpful for cancer-related pain; however, there do not appear to be studies on the effects of CBD alone for cancer-related pain (Blake, Ann Palliat Med 2017). (For more information about cannabinoids and cancer treatment, see the National Cancer Institute’s webpage about this topic.)
Creams, gels and lotions containing CBD are often promoted to treat pain, such as muscle or joint pain. CBD appears to be better absorbed through the skin than THC (Huestis, Chem Biodivers 2007) and there is some evidence that in animals, creams and gels containing CBD may help reduce inflammation in conditions such as arthritis and multiple sclerosis (Hammell, Eur J Pain 2016; Giacoppo, Daru 2015). However, there are no studies on the effects of topical CBD creams, gels or lotions in people.
CBD for Pets:
A study at Cornell University found that giving older dogs with osteoarthritis CBD, compared to placebo, for one month modestly reduced pain and increased activity levels (rising to standing, walking, running, and climbing) as reported by the dogs’ owners, and reduced joint pain upon touch when examined by a veterinarian. However, there were no improvements in lameness or weight-bearing (i.e. reluctance to rise, favoring the affected leg when walking, or limping) as assessed by a veterinarian.
The dose was 2 mg of CBD per kg of bodyweight given twice daily (e.g., for a 20 lb dog: 18 mg of CBD in the morning and again at night), and other regular supplementation was allowed to continue (e.g., glucosamine, fish oil, etc.). No side effects were reported with CBD but there was an increase in levels of the liver enzyme alkaline phosphatase, and the researchers recommended monitoring liver enzymes in dogs receiving CBD until long-term safety studies are conducted. The CBD (a hemp extract in olive oil) was provided by ElleVet Sciences, which funded the study (Gamble, Front Vet Sci 2018).
Legality, Quality Concerns, and What CL Tested For:
Although CBD is not psychoactive, it is not permitted to be sold as an ingredient in dietary supplements in the U.S. as it an FDA approved drug and, prior to that approval, the FDA considered CBD an investigational new drug. (Note: If an ingredient is marketed as a supplement prior to the FDA authorizing its investigation as a drug, it may continue to be marketed as a supplement, but this was not the case with CBD, according to the FDA).
A prescription oral solution of cannabidiol (Epidiolex) was approved by the FDA in June 2018 for the treatment of seizures associated with Dravet syndrome and Lennox-Gastaut syndrome. It is the first FDA-approved drug that contains a purified drug substance derived from marijuana, and the first FDA approval of a drug for the treatment of patients with Dravet syndrome (FDA 2018). Epidiolex is approved at a strength of 100 mg of CBD per milliliter and with a starting dosage of 2.5 mg/kg twice daily, increasing to 5 mg/kg twice daily, and if well-tolerated and needed, up to a maximum dosage of 10 mg/kg twice daily (Epidiolex Prescribing Information). For a person weighing 70 kilograms (154 lbs), this would equal 350 mg to 1,400 mg of CBD per day.
Another condition for which CBD has been investigated as a new drug is cancer pain.
In Canada, cannabidiol is a controlled substance.
Products on the Market
Despite the fact that CBD cannot be legally sold in the U.S. as a dietary supplement, many CBD products are available. Although it does not appear that individuals have been prosecuted for purchasing these products for their own use, the U.S. FDA has issued many warning letters to companies selling products claiming to contain CBD and/or promoting such products as treatments.
The FDA also published the amounts of CBD, THC and other cannabis compounds it found in products it tested in 2015 and 2016. Most products contained very small concentrations of CBD — similar to what is normally found in hemp oil (about 0.0025% CBD) while others contained very large concentrations (25% to 35% CBD) yielding doses similar to those used in clinical trials (typically 200 mg or more per day). Many of the tested products did not contain the levels of CBD they claimed. The FDA cautions that “Consumers should beware purchasing and using any such products.”
The reason why hemp oils would not be expected to contain much CBD is that hemp oil is typically made from hemp seeds, which contain little CBD (although some CBD may contaminate the surface of the seeds). In fact, ConsumerLab.com has tested hempseed oils as part of its review of seed oil supplements (sources of omega-3 and omega-6 fatty acids) and found those products to contain well under 1 mg of CBD per serving. CBD is principally found in the flowers and, to a lesser extent, the upper leaves of the hemp plant. A “CBD oil” product is typically an oil, such as from hemp seed or other sources, to which a CBD extract (from hemp flowers) has been added (Mead, Epilepsy & Behavior 2017).
At least one seller of CBD supplements to the public, PlusCBD LTD, appears to claim that is not illegal to sell these products if they are derived from “industrial” or “agricultural” hemp. Industrial hemp is typically a larger plant with more stalk and less leaves and flowers than that used to produce marijuana or CBD for medical use. It is grown for its fiber (for textiles) and seeds (as food and oil), which would be very low in THC (less than 0.3%) and CBD.
It is true that the U.S. Drug Enforcement Agency (DEA) has stated that CBD in trace amounts from cannabis stalk or seeds is not a controlled substance, in contrast to CBD derived from cannabis flower which is a controlled substance — despite the compound being the same. However, this does not seem to override the FDA’s position that CBD cannot be sold as dietary supplement. It would also seem difficult to obtain large quantities of CBD from industrial hemp or cannabis stalk.
Many states now have medical marijuana laws that permit products with high CBD content to be sold by approved dispensaries and used by residents for medical purposes recommended by a healthcare provider. In addition, several states without medical marijuana laws allow products that are high in CBD (e.g., at least 5%, 10%, or 15% CBD) and low in THC (typically less than 0.3%) to be used for specific medical purposes (typically intractable epilepsy) as approved or recommended by a healthcare professional (See list of states on ProCon.org). However, these state laws do not make the general sale of such products legal, and some specifically require that the products be purchased out-of-state.
A synthetic form of CBD may be dangerous. The form, known as 4-CCB (or 4-cyano CUMYL-BUTINACA) is suspected in 52 cases of adverse reactions, including altered mental status, seizures, shaking, confusion, loss of consciousness, and hallucinations, associated with the use of CBD products sold in Utah between 2017 and 2018. Testing confirmed the presence of this synthetic compound in samples of “Yolo CBD oil” as well as other CBD brands (not named) sold in the state. The tests also revealed these products contained no actual CBD. The symptoms typically began within about 30 minutes of exposure (Horth, MMWR Morb Mortal Wkly Rep 2018). Although this compound was not among those analyzed in ConsumerLab’s tests in this Review, it would seem unlikely to be in these products since each was found to contain actual CBD.
What CL Tested For
Considering the enormous variation that has been shown in the amounts of CBD in marketed products and the fact that many don’t accurately disclose their CBD content, as noted above, ConsumerLab.com purchased a sampling of popular products labeled to contain CBD, cannabinoids (other than THC), and/or hemp extracts and tested them to determine the amounts of CBD and other cannabinoids they contained, comparing these amounts to label expectations. Products were also tested for contamination with lead, cadmium and arsenic. See How Products Were Evaluated for more details.
Products were compared on their label accuracy, quality, and cost. Due to the FDA’s position that CBD is an investigational drug that cannot be sold as a supplement and CL’s requirement that a CL “Approved” product meet FDA labeling requirements, products were not rated as Approved or Not Approved.
What CL Found:
CBD was found in every product and none was contaminated with heavy metals nor contained significant amounts of THC (none exceeded 0.2 mg of THC in a maximum suggested daily serving). However, the dose of CBD per suggested serving ranged 10-fold from 2.2 mg to 22.3 mg, and the cost to obtain 10 mg of CBD ranged over 5-fold from 80 cents to $4.54 (as shown in the graph below). Among the liquid (oil) products, the concentration of CBD ranged from 0.8% to as much as 4.8% by weight, and among capsules containing powders it ranged from 1.3% to 2.3%. More details are found in the Results table further below.
Cost for 10mg of CBD
From among products that passed all of the laboratory tests, CL identified its Top Picks, representing a combination of best value and best quality, described below.
As noted earlier, none of the products contained more than 0.2 mg of THC per suggested maximum daily serving (or per capsule when there was no suggested serving size). It would seem unlikely that such a small amount of THC would cause a positive result on drug tests for THC. In studies, consuming hemp oil providing a daily dose of THC of less than 0.6 mg has generally not resulted in a positive result on standard drug tests (using a 50 ng/mL limit), although there is some variation among individuals.
For example, in a study among 15 adults, one person had a positive drug test at a dose of 0.6 mg of THC per day (Leson J Anal Toxicol 2001), while in another study, one of seven adults tested positive at a dose of just 0.39 mg of THC per day (Gustafson, Clin Chem 2003) — although this is still twice the maximum amount found in products in this Review. Nevertheless, keep in mind that some products on the market may contain more THC than found in the products tested by ConsumerLab for this Review. Also be aware that even regular hemp oil and hemp seed can contain small amounts of THC and, at the right dose, result in a positive drug test (See Concerns and Cautions).
CBD/Hemp Extracts for People
Top Pick: Bluebird Botanicals Hemp Classic 6x Concentrated provided CBD at one of the lowest costs (82 cents per 10 mg) and had by far the highest concentration of CBD (4.8% of the oil is CBD, compared to 0.8% to 1.7% for other oils). It also contained a small amount of other cannabinoids, as one would expect from hemp extract. The suggested serving on the label is 15 drops (found to provide 22.3 mg of CBD and 1. 1 mg of other cannabinoids, costing $1.83), and the label suggests taking that dose twice or more per day.
A close second for Top Pick is Elixinol Natural Drops Hemp Oil + Coconut Extract, which is slightly less expensive than Bluebird to get CBD (80 cents per 10 mg). However, it does not contain other cannabinoids because it is not made from a hemp extract, but contains hemp oil plus added CBD. It does, however, state a specific amount of CBD on its label — 5 mg per ½ dropperful, and it contained a bit more than that — we found 6.2 mg. Interestingly, SOL CBD Pure Hemp Extract appears to be very similar to Elixinol, listing the exact same ingredients, but it costs twice as much as Elixinol and its name does not seem particularly appropriate since it was not found to contain other cannabinoids expected in a hemp extract.
Most products were predominately, if not exclusively, CBD, with only small amounts of other cannabinoids. The only product with a much higher amount of other cannabinoids was Endoca Raw Hemp Oil, which had almost equal amounts of CBD (5.5 mg) and CBDa (4.9 mg) per capsule.
Getting a higher dose: Be aware that none of the products provide the high doses of CBD typically used in clinical trials, and the benefit of these lower doses is not clear. If you are seeking higher strengths of CBD, i.e., such as 50 mg or more per dose, there are products on the market that claim such amounts, but they do not always contain what they claim. The FDA’s tests in 2015 showed that products such as Hemp Honey 21% Cannabidiol Oil, 21% CBD Hemp Oil Treatment, 26% Hemp Oil Treatment, and UltraCBD contained little to no CBD. However, the FDA did identify several products in 2016 that contained the high concentrations listed on their labels such as Herbal Renewals 25% CBD Hemp Oil Gold Label, US Hemp Wholesale 25% CBD Hemp Oil Supplement Gold Label, Endoca Hemp Oil 15% CBD (1500 mg), and iHempCBD Filtered CBD Hemp Oil 35.51%.
These higher-dose products tend to be very expensive. For example, Endoca’s 1500 CBD mg (30 capsules, each with 50 mg of CBD), is $156 compared to its 300 mg CBD which is $31.[Note: The 300 mg CBD product is different from the Endoca 300 mg CBD + CBDa product tested in this Review.] The cost to get CBD from each of these products, assuming they contain what they claim, comes out about the same — $1 per 10 mg, which is about 20 cents more than from the best priced products in this Review. You can see, though, that if you want a daily dose of, say, 500 mg of CBD, it could easily cost $40 to $50 per day.
CBD/Hemp Extracts for Pets
Top Pick: CW [Charlotte’s Web] Paws MCT Oil provided CBD at a much lower cost than Canna-Pet: 10 mg of CBD costs $1.14 from CW but a whopping $4.54 from Canna-Pet. CW is bottled oil, while Canna-Pet is a powder-filled capsule. Interestingly, CW’s product for people, CW Everyday Plus, is essentially the same oil as CW Paws: both were found in testing by ConsumerLab to provide about 16 mg of CBD per milliliter (ml) (2 dropperfuls of Everyday or 1 dropperful of Paws, which has a larger dropper), but this dose cost $2.47 from EveryDay Plus versus $1.87 from CW Paws. The only significant difference is that Everyday Plus has mint chocolate flavoring.
An even lower cost option than CW Paws MCT Oil, would be one of the product marketed for use by people, such as Bluebird, Elixinol, and Plus +CBDOil.
Test Results by Product:
The table below lists test results and information for nine products containing CBD grouped first by those for people and then by those for pets. Products are shown alphabetically within each category. ConsumerLab.com selected all of these products based on reader suggestions and popularity in the marketplace.
Also shown below for each product is the claimed type and amount of hemp ingredient and cannabinoids per serving or unit, the serving size recommended on the label, the amount of CBD and other cannabinoids found, dietary designations if claimed on the label (i.e. Kosher, Non-GMO) and ingredient and cost comparisons. Check marks in the table indicate that a product passed ConsumerLab.com’s quality criteria for that attribute (see Passing Score). The full list of ingredients is available for each product by clicking on the word “Ingredients” in the first column.
|RESULTS OF CONSUMERLAB TESTING OF CBD OIL PRODUCTS|
|Product Name, Amount Listed of Hemp Oil/Extract per Unit, and Suggested Daily Serving on Label||Claimed Amount of Hemp Oil/Extract Per ServingClaimed Amount of Cannabinoids Per Serving||TEST RESULTS||Cost For Suggested Serving On Label[Cost Per 10 mg Cannabidiol (CBD) Found]Other Notable Features Price Paid|
|Contained Labeled Amount of Cannabinoids1 per serving(% CBD of oil or powder)||Did Not Exceed Contamination Limit for Lead, Cadmium and ArsenicDid Not Exceed Limit for THC|
Bluebird Botanicals Hemp Classic 6 x Concentrated, 1,500+ mg (hemp extract and hemp oil; 15 drops [0.5 mL], twice or more per day3)Dist. by Bluebird Botanicals
|Amounts of hemp extract and organic virgin hemp seed oil not listed25 mg|
full spectrum cannabinoidsBottled oil
CBD: 22.3 mg per 15 drops
Other cannabinoids:1.1 mg per 15 drops4.8% of oil is CBDHighest concentration of CBD
|$1.83[$0.82] Low cost for CBD$109.80/1 fl. oz. [30 ml] bottle (approx. 60 servings)|
CW™ [Charlotte’s Web] Everyday Plus – Infused Oil Mint Chocolate (28 mg hemp extract per 2 full droppers [1 mL]; 2 full droppers, twice daily)Mfd. by CW Hemp
(above ground plant parts)Amounts of cannabinoids not listedBottled oil
CBD: 16.1 mg per 2 full droppers
Other cannabinoids:none1.7% of oil is CBD
|$2.47[$1.54]Vegan$74.24/1 fl. oz. [30 ml] bottle (approx. 30 servings)|
Elixinol™ Natural Drops Hemp Oil + Coconut Extract with Naturally Occurring CBD (16.7 mg hemp oil per ½ dropper [0.5 mL]; ½ dropper, twice daily)Dist. by Elixinol LLC
hemp oil (seeds and stalks)5 mg
CBD: 6.2 mg per ½ dropper
Other cannabinoids:none1.3% of oil is CBD
|$0.50[$0.80] Lowest cost for CBD$29.99/1 fl. oz. [30 ml] bottle (approx. 60 servings)|
Endoca Raw Hemp Oil (hemp oil and CBD + CBDa; no suggested serving or daily serving size4)Dist. by Endoca
|Amount of hemp oil not listed10 mg5|
CBD + CBDaOil in medium/large capsule
CBD: 5.5 mg per capsule
Other cannabinoids:4.9 mg per capsule
(4.9 mg CBDa)1.1% of oil is CBD
|$1.035[$1.88]Omega-3 (40 mg), omega-6 (133.3 mg), vitamin E (266.67 mcg)Vegan$31.00/30 capsules|
Plus +CBD Oil Capsules 10 mg CBD (125 mg hemp oil per capsule; 1 capsule, once daily)Dist. by CV Sciences, Inc.
dried hemp oil (above ground plant parts) containing 10 mg CBDPowder in large capsule
CBD: 9.8 mg per capsule
Other cannabinoids:1.2 mg per capsule2.3% of powder is CBD
PrimeMyBody Nano-Enhanced Hemp Oil (24 mg hemp extract per 4 pumps [2 mL]; 1 to 4 pumps [0.5 to 2 mL], once or more daily6)Dist. by PrimeMyBody
hemp extract (stems and stalks) containing 16 mg phytocannabinoid diolsBottled oil
CBD: 16.2 mg per 4 pumps
Other cannabinoids:none0.8% of oil is CBD
|$4.76[$2.94]Gluten free$119.00/1.7 fl. oz. [50 ml] bottle (approx. 25 servings)|
SOL CBD Pure Hemp Extract (16.7 mg hemp oil per ½ dropper [0.5 mL]; ½ dropper, twice daily)Dist. by Halcyon Botanicals
hemp oil (seeds and stalks)5 mg
CBD: 5.2 mg per ½ dropper
Other cannabinoids:none1.1% of oil is CBD
|$1.03[$1.99]$124.00/2 fl. oz. [60 ml] (two pack of 1 ounce bottles) (approx. 120 servings)|
Canna-Pet® Advanced (organic hemp flour; 1 capsule, once or twice daily7)Dist. by Canna-Pet®
|Amount of organic hemp flour not listedAmounts of cannabinoids not listedPowder in medium/large capsule||Found:|
CBD: 2 mg per capsule
Other cannabinoids:0.2 mg per capsule1.3% of powder is CBD
CW™ [Charlotte’s Web] Paws MCT Oil (25 mg hemp extract per 1 full dropper [1 ml]; ¼ to 1 full dropper [0.25 mL to 1 mL]; twice daily)Mfd. by CW Hemp
hemp CO2extractAmounts of cannabinoids not listedBottled oil
CBD: 16.4 mg per full dropper
Other cannabinoids:none1.7% of oil is CBD
|$1.87[$1.14]$187.10/3.38 fl. oz. [100 ml] bottle (approx. 100 servings)|
Tested through CL’s Quality Certification Program prior to, or after initial posting of this Product Review.1 Variation permitted of up to 25% more and 10% less than listed amount.
2 Not tested but claimed on label.
3 Label states “Take one or more servings by mouth, twice per day, or as directed by a medical professional.”
4 There are no listed serving size and daily serving size.
5 Based on taking 1 capsule per serving.
6 Label states “Take 1-4 pumps by mouth, holding for 30 second before swallowing. Best taken on an empty stomach 10 minutes before meals.”
7 Label states “Dogs Under 20lbs (9 kg): 1 capsule 2x/daily. Cats Under 20lbs (9 kg): 1 capsule daily.”
Unless otherwise noted, information about the products listed above is based on the samples purchased by ConsumerLab (CL) for this Product Review. Manufacturers may change ingredients and label information at any time, so be sure to check labels carefully when evaluating the products you use or buy. If a product’s ingredients differ from what is listed above, it may not necessarily be of the same quality as what was tested.The information contained in this report is based on the compilation and review of information from product labeling and analytic testing. CL applies what it believes to be the most appropriate testing methods and standards. The information in this report does not reflect the opinion or recommendation of CL, its officers or employees. CL cannot assure the accuracy of information.
What to Look for When Buying and Using:
Read Labels Carefully
As noted earlier, hemp oil would not be expected to contain much CBD, while hemp extract or products that specifically list CBD as an ingredient would be expected to contain CBD. Ideally, look for a product that lists the amount of CBD per serving (not just per entire bottle). If a product lists “cannabinoids” it may contain some CBD but you won’t know how much.
Most of the research with CBD has involved high doses (several hundred milligrams daily). This is much more than you’ll typically get from products being sold on the market. Here’s what’s been shown to work in preliminary clinical studies, as discussed in more detail in the What It Does section:
- Anxiety (relating to public speaking): 300 mg to 600 mg of CBD daily
- Insomnia: 160 mg of CBD 30 minutes before bedtime to increase sleep time (but will not decrease the amount of time it takes to fall asleep)
- Reduction in seizures: 20 mg of CBD per kilogram of body weight daily (e.g., for a 70 kg adult, this would be 1,400 mg of CBD)
- Schizophrenia: 1,000 mg of CBD daily
- For Dogs with Osteoarthritis: 2 mg per kilogram of bodyweight, twice daily. (e.g., for a 20 lb. dog: 18 mg of CBD in the morning and again at night).
How to take
CBD is fat-soluble (i.e., lipophilic) and taking CBD with, or shortly, after a meal containing fats can dramatically increase its bioavailability which otherwise may be as low as 6% (Devinksy, Epilepsia 2014). A 5-fold increase in blood levels of CBD occurred when an oral solution of CBD (in an alcohol and oil base) was taken with a high-fat/high-calorie meal (i.e., a large meal containing fats) rather than on an empty stomach (FDA – Epidiolex labeling revised 6/2018). Special formulations of CBD exist that may enhance absorption of CBD. However, comparative data has not been published for these formulations and, moreover, it is not known if any would increase CBD bioavailability as much as simply taking CBD with, or shortly after, a fatty meal. Fatty meals not only provide fats but stimulate bile secretion into the intestine, facilitating absorption of fat-soluble compounds like CBD.
After taking CBD orally, maximal blood levels are reached within about 2.5 to 5 hours. CBD remains in the blood for a fairly long time — studies have shown its half-life (i.e., the time for blood levels to fall by half) to be 18 to 32 hours (Devinksy, Epilepsia 2014) to as long as 56 to 61 hours after 7 days of repeated high-dosing (FDA – Epidiolex labeling revised 6/2018).
Concerns and Cautions:
CBD can cause side effects and interact with certain medications and conditions, although these effects have typically been reported only with very high daily intake, i.e., hundreds of milligrams daily.
- High daily doses of CBD (20 mg per kg of body weight, i.e., hundreds of milligrams) may cause decreased appetite, diarrhea, vomiting, fatigue, fever, somnolence, and abnormal results on liver-function tests (Devinsky, New Eng J Med 2017; Thiele, Lancet 2018).
- Drops in blood pressure (of 10 to 20 mm Hg) upon standing were reported in each of five patients with movement disorders given CBD (100 mg to 500 mg) for several weeks. Two patients also reported lightheadedness. A worsening of symptoms of Parkinson’s disease was also noted. In addition, dry mouth occurred in two of the five patients (Consroe, Int J Neurosci 1986). Dry mouth (which also occurs with marijuana use) may be due to inhibition of cells in the salivary glands that contain cannabinoid receptors CB1 and CB2 (Prestifilippo, Exp Biol Med 2006), and CBD can interact with such receptors (Pertwee, BJP 2008).
- CBD should be used with caution with sedative and sleep-inducing medications, as it may enhance their effects. CBD could also potentially increase the effects of herbs and supplements that have a sedating effect, such as melatonin, valerian, SAMe, ashwagandha and others, although there do not appear to be any published reports of this occurring.
- CBD can increase blood serum levels of antiepleptic drugs (Gaston, Epilepsia 2017). CBD may increase the blood-thinning effects of warfarin (Coumadin, Jantoven) likely because CBD competes for the same liver enzymes that break down warfarin and other drugs. This was observed in a man with post-stroke epilepsy taking warfarin: His INR (a measure of how long it takes blood to clot) began increasing several weeks after starting CBD (Epidiolex, Greenwich Biosciences, Inc.) for his seizures. His CBD dosing started with several hundred milligrams daily and increased to over 1,000 mg, at which point his warfarin dose had been reduced by approximately 30% (Grayson, Epilepsy Behav Case Rep 2017).
- A small study in healthy men found that a single dose (400 mg) of antifungal drug ketoconazole(Nizoral, Xolegel, Extina) increased blood levels of CBD, while a single dose (600 mg) of the antibiotic rifampicin (Rifadin) decreased blood levels of CBD (Stott, Springerplus 2013).
- In laboratory and/or animal studies, CBD has been shown to inhibit CYP3A4, CYP3A5 and CYP2D6 enzymes (U.S Department of Health; Yamaori, Life Sci 2011; Iffland, Cannabis Cannabinoid Res 2017). Potentially, this could slow the breakdown of drugs metabolized by these enzymes, leading to higher blood levels of these drugs and an increased risk of side effects — although this effect has not been reported to occur in studies of CBD in people. Nevertheless, use with caution if you take medications metabolized by one or more of these enzymes, including macrolide antibiotics such as clarithromycin (Biaxin) and azithromycin (Zithromax), cyclosporine (Sandimmune), sildenafil (Viagra), antihistamines, Haloperidol (Haldol), certain statin medications such as atorvastatin (Lipitor) and simvastatin (Zocor), testosterone, progesterone, nifedipine (Procardia XL), metoprolol (Lopressor, Toprol XL), the proton pump inhibitor drug omeprazole (Zegerid, Prilosec OTC) and the antipsychotic drug risperidone (Risperdal), ondansetron (Zofran), paroxetine (Paxil), flecainide (Tambocor) and others.
- CBD supplements can potentially contain enough THC to cause a positive drug test for marijuana, although, as noted in the What CL Found section, none of the products tested in this Review provided amounts likely to cause such a result. Even consuming hemp seeds or hemp oil could cause a positive result on a blood test for THC, but because amounts of THC in hemp seeds used for these products are so low, you would have to consume large amounts. For example, to get 0.6 mg of THC, you would typically have to consume 8 tablespoons of hemp oil or 300 grams (about 30 tablespoons) of hulled hemp seeds (Leson J Anal Toxicol 2001). However, there can be large variations in the amounts of THC in hemp seeds. An analysis of three brands hemp seed purchased from grocery stores in Canada found that all three exceeded Canada’s legal limit for THC in hemp (10 mcg/g) and one was 7-to-12 fold higher than this limit, such that only 30 grams (about 3 tablespoons) would provide 3.8 mg of THC (Yang, Cannabis Cannabinoid Res 2018). There is also a report of a man who consumed two tablespoons of cold-pressed hemp oil (Hemp Liquid Gold, Health From the Sun) for four days and tested positive for THC on a standard drug test. The amount of THC in the product was not reported (Struempler, J Anal Toxicol 1997). Due to these possibilities, some branches of the U.S. military, including the Army, Air Force and Coast Guard forbid the use of any hemp-based products, including hemp oil, hemp seeds, and foods that contain hemp, such as yogurt containing hemp seeds. Interestingly, the World Anti-Doping Agency, which helps to oversee drug policies in sports, announced in 2018 that cannabidiol is no longer prohibited by the organization, but cautioned that “cannabidiol extracted from cannabis plants may also contain varying concentrations of THC, which remains a prohibited substance.” (Note: Policies on hemp and CBD consumption in professional sports organizations still vary based on the organization).
- The American Academy of Pediatrics has not endorsed Cannabis and cannabinoid use because of concerns about brain development (National Cancer Institute 2017).
- In dogs, giving 2 mg per kilogram of bodyweight, twice daily. (e.g., for a 20 lb dog: 18 mg of CBD in the morning and again at night) for a month was found so cause an increase in levels of the liver enzyme alkaline phosphatase, and the researchers recommended monitoring liver enzymes in dogs receiving CBD until long-term safety studies are conducted (Gamble, Front Vet Sci 2018).