Product Reviews
CBD & Hemp Extract Supplements, Lotions, and Balms Review
 

Initial Posting: 2/8/18   Last Update: 4/19/19
CBD and Hemp Oils Reviewed by ConsumerLab.com

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Summary:
  • 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 (See What It Is and What It Does).
  • What did CL find? ConsumerLab found the dose of CBD per suggested serving ranged 15-fold from 1.3 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 (or $4.73 when including balms). Two products were discovered to contain less CBD than listed and one contained much more. (See What CL Found and use the Results table to compare the amounts of CBD and other cannabinoids in products).
  • Top Picks ConsumerLab selected two Top Picks 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 or cannabidiol per serving (and don't confuse that with the amount per entire bottle). 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. (See ConsumerTips)
  • 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.

Epilepsy and seizure disorders
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 epilepsy known 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% occurred 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).

Parkinson's disease and movement disorders
CBD does not appear to improve motor symptoms of Parkinson's disease, such as tremor and difficulty initiating movement, or involuntary movements (dyskinesia) associated with the use of the anti-Parkinson's drug levodopa. However, CBD may be helpful for non-motor symptoms of Parkinson's disease, such as psychosis, mood and sleep disturbances — although more research is needed (Crippa, Eur Arch Psychiatry Clin Neurosci 2019).

For example, there have been some preliminary reports of CBD oil (150 mg to 400 mg) improving symptoms of psychosis, with no worsening of motor function, in individuals with Parkinson's disease and psychosis who were taking levodopa (Zuardi, J Psychopharmacol 2009). 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). A small, double-blind, placebo-controlled study in Brazil found no improvement in motor function in men and women with mild to moderate Parkinson's disease without other psychiatric conditions (average duration of disease 8 years) who took CBD oil (75 mg or 300 mg) daily in addition to their regularly prescribed anti-Parkinson medication for six weeks -- but those who took the 300 mg dose had significant improvements in Parkinson's Disease Questionnaire-39 total scores, and measures of quality of life such as activities of daily living, "stigma" and emotional well-being. No adverse effects were associated with the use of the CBD oil (Chagas, J Psychopharmacol 2014).

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, at the highest dosages (300 mg to 500 mg) 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).

Schizophrenia and psychosis
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).

Anxiety, PTSD, and sleep
Studies in animals as well as several small studies in people suggest CBD may help reduce anxiety. For example, a small placebo-controlled 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 (Crippa, Neuropsychopharmacology 2004). Studies have also found CBD to reduce anxiety with social speaking when given 90 minutes before speaking at a dose of 300 mg, while a lower dose (150 mg) was not effective and there were mixed results with a higher dose (600 mg) ((Bergamaschi, Neuropsychopharm 2011), Zuardi, J Psychopharmacol 1993, Linares, Braz J Psychiatr 2018).

Case reports from an outpatient mental health clinic in Colorado suggest that even lower doses of CBD may be helpful with anxiety and related sleep disorders. (Bear in mind that case reports are not controlled studies, so these benefits remain to be proven.) In a group of 72 men and women treated with CBD daily for two months, anxiety scores decreased within the first month in 79.2% of patients and remained decreased during the study duration. Sleep scores improved within the first month in 66.7% but fluctuated over time. It's important to note that 15.3% reported a worsening of anxiety and 25% reported a worsening of sleep, and similar percentages were reported in the second month of supplementation. Most of the participants took one capsule daily containing 25 mg of CBD oil (provided by CV Sciences Inc., makers of PlusCBD Oil, although it was not a sponsor of the study), and continued taking their regularly prescribed medications. For anxiety, CBD was taken after breakfast, while, for sleep, it was taken after dinner. CBD was generally well-tolerated, although two patients discontinued treatment within the first week because of fatigue and three noted mild sedation that appeared to abate after a few weeks of treatment. CBD was discontinued for one patient with a developmental disorder in whom treatment appeared to cause disinhibition in the form of inappropriate sexual behavior (Shannon, Perm J 2019).

Another series of case reports from the clinic in Colorado suggested that CBD may help relieve symptoms of post-traumatic stress disorder (PTSD). In a group of 11 adults with diagnosed PTSD, overall symptoms decreased by an average of 28% over a 2-month period of CBD supplementation. The average daily CBD dose was 33.4 mg at the start, increasing to 44.6 mg by the end of the study. The participants took CBD as 25 mg capsules and/or an oral spray (1.5 mg of CBD per spray) (Elms, J Altern Complement Med 2019). Separately, the same clinic reported that CBD appeared to be helpful to a 10-year old girl with anxiety and sleep disorder due to PTSD caused by sexual abuse. She took 25 mg of CBD at bedtime and 6 mg to 12 mg of CBD from a sublingual spray as needed throughout the day for 5 months. Her anxiety and sleep improved 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.

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).

Glaucoma
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.

Pain
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).

Cancer
Preliminary evidence suggests that CBD may have anti-cancer properties and enhance the immune response to cancer. Although clinical studies have not been conducted, a case was reported in the UK of a man in his early 80s with lung cancer (biopsied as adenocarcinoma) who, after declining traditional therapies, had a dramatic reduction in tumor size after self-administering low-dose CBD twice daily (starting at just 1.32 mg of CBD twice daily for one week, and then 6 mg of CBD twice daily for another three weeks — each dose consisted of 9 drops (0.3 mL) of "MyCBD" oil labeled as 2% CBD. He took this daily dose again for a week after learning of the tumor reduction but stopped as he did not like the taste and it caused him slight nausea. A scan two months later showed the tumor remained stable in size. Further research is needed on CBD's effect on cancers (Sule-Suso, Sage Open Medical Case Reports, 2019). (For more information about cannabinoids and cancer treatment, see the National Cancer Institute's webpage about this topic.)

Colds and flu
CBD is sometimes promoted to fight colds or the flu, but there is little evidence to support this use. Preliminary evidence from animal studies suggests that CBD may decrease the inflammatory response of the immune system to infections such as pneumococcal meningitis (Barichello, Eur J Pharmacol 2012). (It also seems to dampen the immune system's response in experimental models of autoimmune diseases, which could potentially be beneficial (Kozela, Br J Pharmacol 2011)). Similarly, THC has been found to reduce the immune system response in mice infected with influenza A (Buchweitz, J Pharmacol Exp Ther 2007). In a study in which high doses of CBD (hundreds of milligrams per day) were given to children and young adults (Devinsky 2017 --- see the Epilepsy and seizure disorder section above), the number of upper respiratory infections reported was slightly higher among those who took CBD compared to placebo (11% vs. 8%, respectively). However, there do not appear to be any published studies on the effects of CBD supplementation for preventing or reducing symptoms of colds or the flu in people.

Topical CBD
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, to date, clinical studies have not provided convincing evidence of a benefit with topical CBD. In a study of 13 young adults, CBD cream applied to the front thigh area after leg exercises (a series of squats) did not decrease delayed onset muscle soreness (DOMS) in the 48 hours following exercise compared to placebo (petroleum jelly). The cream contained 200 mg of CBD in each 1-oz. container, which was shared among all of the participants, although the specific amount of cream or CBD was not specified (Garcia, Int J Exc Sci 2019 - Abstract plus correspondence with ConsumerLab). In the other study, gel containing 10.5 mg or 21 mg of synthetic CBD was applied daily to the knees of people with knee osteoarthritis. Although both groups experienced reductions in "worst knee pain" scores, these reductions were not statistically significant compared to the reduction in pain scores for placebo group that used gel without CBD. The study was conducted by a company (Zynerba) seeking to develop the synthetic CBD (ZYN002) as a drug and the results have, to date, been published only in a 2017 news release.

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).

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