Highs and Lows: CBD Oil for Anxiety Disorders
Almost half of all CBD users in the US use CBD to help relieve anxiety and stress. This new medication offers a potential alternative for Australian patients who experience side effects or lack of efficacy from traditional medicines prescribed for anxiety.
Quick Summary: The Highlights
- Current evidence indicates that cannabidiol (CBD) oil has considerable potential as a treatment option for multiple anxiety disorders.
- Studies show CBD oil is safe and well tolerated for short-term use, even at high doses.
- CBD oil does not cause a high that is generally associated with recreational cannabis use.
- If your regular doctor is unwilling to prescribe, you can do our quick eligibility test and book in directly with one of our doctors.
The ABCs of CBD: What Is It?
Cannabidiol (CBD) belongs to a class of molecules called cannabinoids. These are chemicals found in cannabis (marijuana and hemp) plants. 1 CBD oil contains CBD dissolved in a carrier oil. 2
How Does It Work?
The endocannabinoid system (ECS) is a complex cell-signalling system, identified in the early 1990s by researchers investigating THC (delta-9-tetrahydrocannabinol), a common cannabinoid. The system is active in your body, even if you don’t use cannabis. The ECS consists of cannabinoid receptors found throughout your body.
Our brain contains the highest number of cannabinoid receptors in the human body. CBD modulates how our brain cells behave by controlling the release of neurotransmitters (the body’s chemical messengers).
CBD can also activate non-cannabinoid receptors, such as serotonin receptors. Low levels of brain serotonin, a neurotransmitter, is associated with depression and anxiety. CBD may help the brain use serotonin more effectively in some people, although this is not yet fully understood. 3
How Is CBD Different to THC?
More than 100 different types of cannabinoids have been found in the leaves and flowers of the cannabis plant. The two most common cannabinoids used in medicinal cannabis products are CBD and THC.
While from the same class of molecules, CBD and THC work differently to one another. 4
THC may be used to reduce symptoms of nausea, vomiting, pain and muscle spasticity as well as improve sleep and appetite. In some people who take too much, THC may cause a high that is generally associated with recreational cannabis use. 5
CBD does not cause a high and may reduce the unwanted side effects of THC. 5
Evidence Snapshot: What Does the Research Say?
While more research is needed to better understand how and why CBD works in the treatment of anxiety disorders, it is relatively safe. 6 CBD could be an option for those patients who have not experienced benefits from traditional medication or have experienced side effects from these medications.
Current evidence indicates CBD has considerable potential as a short-term treatment for multiple anxiety disorders. Further studies are needed for to determine its use for long-term treatment. 7
Table 1 (below) summarises the evidence from short-term psychological studies of CBD oil for anxiety disorders. CBD was initially found to reverse the anxiety effects of THC when used together.
However, it had no effect on anxiety when used alone at the dosages given in these studies. 8,9 At higher dosages, CBD reduced anxiety associated with a simulated public speaking test in healthy adults, as well as in adults with social anxiety disorder.
It showed a comparable effectiveness to ipsapirone (a 5-HT1A agonist) or diazepam (a benzodiazepine). 10,11
CBD also reduced anxiety in patients undergoing a single-photon emission computed tomography (SPECT) imaging procedure, in both healthy adults and adults with social anxiety disorder. 12
Table 1: Evidence from short-term psychological studies of CBD oil for anxiety disorders
|Study||Measure of anxiety||Results|
|Karniol et al. 8||Anxiety and pulse rate after taking THC||Decrease subjective anxiety and pulse rate|
|Zuardi et al. 9||STAI after taking THC||Decrease in STAI scores|
|Zuardi et al. 10||VAMS, STAI and blood pressure following simulated public speaking test||Decrease in STAI scores, VAMS scores and blood pressure|
|Crippa et al. 12||VAMS||Decrease in VAMS scores|
|Bhattacharyya et al. 13||STAI and VAMS||Decrease in STAI scores and VAMS scores|
|Bergamaschi et al. 11||VAMS, SSPS-N, cognitive impairment, SCR and heart rate||Decrease in VAMS scores, SSPS-N scores and cognitive impairment; no effect on SCR or heart rate|
|Hindocha et al. 14||Baseline VAS anxiety||No significant effect|
SCR = skin conductance response; SSPS-N = negative self-evaluation subscale; STAI = Spielberger’s state trait anxiety inventory; THC = delta-9-tetrahydrocannabinol; VAMS = visual analogue mood scale
Neuroimaging studies have demonstrated modified blood flow in specific areas of the brain associated with anxiety. 12,15
CBD was also found to be effective in reducing anxiety symptoms in patients with anxiety disorders and post-traumatic stress disorder when used in combination with other pharmacological treatment and psychotherapies. 16,17
Anxiety and Depression
A study shows that CBD improve patients’ overall quality of life after 3 weeks of treatment for various conditions. Patients who received CBD for anxiety or depression specifically experienced improvements in their ability to perform daily tasks as well as a reduction in pain and anxiety or depression symptoms. 18
Post-traumatic Stress Disorder and Phobia Therapy
Studies suggest CBD decreased the severity of patients’ post-traumatic stress disorder symptoms when given alongside routine psychiatric care 16 or when given with THC. 19 When taken together with THC, an “entourage effect” occurs. This is where THC enhances the effects of CBD, while CBD counters the adverse effects of THC. 20
A study has demonstrated CBD can enhance the effects of exposure therapy. This is a kind of phobia therapy that helps patients separate certain cues with a fear response. 21
Which Anxiety Disorders Can CBD Oil Help Treat?
Existing pre-clinical evidence strongly supports CBD oil as short-term treatment for the following anxiety disorders: 7
- generalised anxiety disorder
- panic disorder
- social anxiety disorder
- obsessive compulsive disorder
- post-traumatic stress disorder.
What Is CBD Oil’s Place in Anxiety Treatment Pathways?
Anxiety is the most common mental health condition in Australia, with 1 in 4 people (1 in 3 women and 1 in 5 men) experiencing anxiety at some stage in their life. 22 There are many ways to manage anxiety. The sooner people with anxiety get support, the sooner they are likely to recover.
Currently, the main pharmacological treatments for anxiety disorders include selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, monoamine oxidase inhibitors, tricyclics, partial 5-hydroxytryptamine 1A (5-HT1A) receptor agonists, and benzodiazepines. 23 These medicines tend to have adverse effects and a low rate of effectiveness (in about 40 to 60% of patients). 24
Anxiety disorders may also be treated using psychological approaches, such as cognitive behavioural therapy. 24 However, these therapies can be costly and limited to specific situations. 25
CBD oil is not considered first line treatment for anxiety disorders, but may be a suitable alternative when other treatments have been unsuccessful. Evidence supports the use of CBD oil as an effective monotherapy or complementary therapy for treating anxiety disorders. 26
The therapeutic effects of CBD oil for the treatment of anxiety include the reduction of: 27
- muscular tension
- problems in concentration
- social anxiety.
Benefits vs. Risk
CBD oil can be a good alternative when other medicines aren’t working. It is well tolerated, has minimal side effects and has lots of research data strongly supporting its anxiolytic effects. 10,11
Currently, CBD oil is only available on the Pharmaceutical Benefits Scheme (PBS) for treatment of Dravet syndrome, also known as severe myoclonic epilepsy in infancy (SMEI). 28
Out of pocket costs may be high for indications not covered on the PBS. On average, patients who are using CBD oil for anxiety disorders will need to pay between $4–10 per day for their medicine.
How Do I Take CBD for Anxiety?
You can take CBD products in several ways: 29
- by using a spray into your mouth or under your tongue (orally or sublingually)
- by swallowing oils, liquid capsules or tablets (orally)
- by vaporising CBD flower – heating the flower and inhaling the vapour using a flower vaporizer device
- by vaporising CBD extract cartridges through a metered dosage device
Smoking CBD oil or flower is not recommended as it increases the risk of cancer, stroke, heart disease and other serious health conditions. 29
Taking CBD oil orally allows you to easily measure the exact dose. When taken orally, the effects of CBD begin working within 30 minutes to 2 hours. Vaping CBD results in more immediate effects. 30
You may choose to take CBD oil in the morning to relieve anxiety throughout the day, or just before a stressful event, such as giving a speech.
CBD for Anxiety Dosing
A recent review found that different studies don’t have a consensus on a single universal dosage of CBD oil that everyone should take for treatment of anxiety disorders. Rather, it highlighted that different people respond to different dosages of CBD oil. Most studies used dosages between 20 to 1,500mg per day. 6
A 2018 study found that 300mg of CBD, given 90 minutes before a simulated public speaking test, significantly reduced speakers’ anxiety. Those who received a lower dose (150mg) and higher dose (600mg) saw little benefit. 31 These results highlight how dosages can be variable and a higher dosage does not necessarily mean it is more effective.
A 2019 study tested CBD oil in lower doses (25 to 75mg/day) and found that anxiety decreased within the first month and remained low for most patients. 17
The dosage of CBD oil you should take depends on a range of factors, including:
- your weight
- the condition being treated
- the concentration of CBD in the product.
However, few commercially available CBD products contain enough CBD to replicate the therapeutic effects seen in clinical trials. 32
It is important that you speak with your doctor about the appropriate dosage and any potential risks before starting CBD oil. Generally, it Is best to start with a smaller dosage and gradually increase until the desired effect is reached (known as titrating the dosage).
Unless your doctor recommends a specific dose, start by taking 10 to 20mg a day for a week to ensure you can tolerate it and that you don’t experience any unwanted adverse effects. If the desired effect is not achieved, try increasing in increments of 5mg each week until the desired effect is reached. 33 Table 2 (below) summarises the successful dosages that studies have evaluated for anxiety relief specifically.
Table 2: Successful dosages of CBD oil evaluated for anxiety relief
|Dosage||Condition being treated|
|600mg 11||Social anxiety disorder before a simulated public speaking test|
|300mg 31||Anxiety before a simulated public speaking test|
|25 to 75mg 17||Generalised anxiety and/or sleep problems|
|33 to 49mg per day 16||Post-traumatic stress disorder, in addition to routine psychiatric treatment|
Figure 1: Successful dosages of CBD oil evaluated for anxiety relief
CBD Oil Dosing Research
More studies with standardised approaches to dosing are needed to determine the appropriate dosing strategy for CBD oil and its place in therapy. 26
Calculating CBD Oil Dosage for Anxiety
CBD oil usually comes in a dropper bottle. The packaging may specify how much CBD is in a single drop. This will allow you to determine how many drops you need.
Sometimes, it might be difficult to calculate how much CBD is in one drop because the packaging specifies the total amount of CBD in the entire bottle, not how much is in a single drop. As a rule of thumb, one drop (not the full dropper) is about 0.05mL.
For example, a 15mL bottle of CBD oil contains 300 drops. If the strength of the formulation is 30mg/mL, each drop contains 1.5mg of CBD.
When Should CBD Oil Be Taken?
You can take CBD oil with or without food. However, taking it with food (particularly a high fat, high calorie meal) can increase the level of CBD in your blood 34 and make it more effective. Because of this, you need to be consistent when you take CBD oil. Consistent dosing will minimise variability in the way the medicine works.
Is It Possible to Take Too Much CBD?
Studies have shown that dosages of up to 5,000mg a day are safe and well-tolerated. 35 However, it is important to remember that more research is needed to understand the potential long-term effects of CBD oil at these dosages.
Is CBD Oil for Anxiety Safe to Take?
Like all medicines, CBD oil can have side effects. The extent of these effects vary with the type of product and between individuals. In general, the side effects of CBD products are less than those for THC products. 5 A recent review shows that extensive research has found CBD oil to be relatively safe. 6
Known side effects of CBD include: 5
- fatigue and sedation
- dizziness (vertigo)
- nausea and vomiting
- decreased or increased appetite
- dry mouth
Continuous use of CBD oil is safe and well tolerated. 6,11 Studies show that CBD oil is well tolerated even at high doses (up to 5,000mg). 35
Contact your doctor if you experience any medicine-related side effect or adverse event.
Withdrawal and Dependence
Withdrawal symptoms from CBD oil is not associated with discontinuation and it may be stopped without gradually reducing. 35
CBD oil demonstrates no potential for abuse or dependence. 36,37
CBD oil blocks CYP3A4, an enzyme responsible for breaking down many medicines. This can increase the level of medicines in your system, resulting in unwanted or harmful side effects. There is potential for CBD oil to be associated with drug interactions through blocking this enzyme, but it is not yet clear whether these effects occur at CBD oil’s usual dosage ranges. 27
High dosages of CBD oil may increase plasma concentrations of certain epilepsy medicines such as clobazam and topiramate, while abnormal liver function test results were noted in patients taking CBD oil together with valproate. Although the observed level changes of the epilepsy medicines remained within the accepted therapeutic dosages, the study emphasises on the importance of monitoring serum antiepileptic drug levels and liver function tests during treatment with CBD oil. 38
A recent comprehensive review found that there have been reports of CBD oil interacting with epilepsy medicines, antidepressants, opioid analgesics and THC, as well as several other common medicines such as paracetamol, and substances including alcohol. 39
It is important that you speak with your doctor about any vitamins, supplements, prescription and over-the-counter medicines you are taking before starting or stopping CBD oil.
What should patients and caregivers know?
- CBD oil does not cause a high as it does not contain THC.
- Assess your sensitivity to CBD oil. Your individual ability to tolerate CBD oil can play a role in determining how much you need. Unless your doctor recommends a specific dose, start with a low dose and gradually increase until you achieve the desired effect.
- Although CBD oil may help with your anxiety, do not stop any medicines you are already using without talking to your doctor first. Suddenly stopping your prescription medicines may cause you to experience withdrawal symptoms.
- As CBD oil is not intoxicating, there are no restrictions around driving when taking products that contain only CBD. However, take care when taking products containing both CBD and THC as it is illegal to drive while you are taking THC products. 29
What Are the Next Steps?
In most states in Australia, most GPs and specialists can prescribe CBD oil. However, they will need to apply under the special access scheme.
If your doctor is unwilling to apply on your behalf or uncomfortable prescribing medical cannabis, they can refer you to our clinic. We do virtual consultations nationwide and in-person at our flagship clinic in Sydney.
Click here for a quick online eligibility test to see if you qualify.
You can also call us at (02) 9098 9128 or email us at [email protected] and we can advise if medical cannabis could be an option for your condition.
How To Use CBD To Help Alleviate Anxiety
Dr. Bindiya Gandhi is an integrative medicine physician with expertise in functional and holistic medicine based in Atlanta, Georgia.
Commissions we earn from partner links on this page do not affect our opinions or evaluations. Our editorial content is based on thorough research and guidance from the Forbes Health Advisory Board.
Table of Contents
- CBD for Anxiety
- How to Use CBD for Anxiety
- CBD Dosage for Anxiety
- Potential Risks and Side Effects
While delta-9-tetrahydrocannabinol (THC) can have a bad rap for being intoxicating and anxiety-inducing, cannabidiol (CBD) can actually be used to relieve anxiety. Research supports this benefit, with several studies reinforcing the positive effects CBD can have on various anxiety conditions. In fact, 51% of U.S. adults who use CBD do so to help alleviate their anxiety, according to a recent Forbes Health survey of 2,000 U.S. adults conducted by OnePoll.
CBD isn’t yet legally cleared as an anxiolytic, or anxiety relief medication. Therefore, it’s up to you—and, ideally, a doctor who specializes in cannabis administration—to determine whether CBD is a safe treatment for your anxiety.
Here’s what the science says regarding CBD’s anxiolytic properties, along with experts’ dosage guidelines and advice on how to take CBD safely.
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CBD for Anxiety
The Food and Drug Administration (FDA) has yet to approve any CBD-based medications for anxiety. However, many studies indicate the substance can be an effective anxiolytic.
CBD for Generalized Anxiety
In 2011, a small trial-tested CBD on participants with generalized social anxiety disorder (SAD) and healthy control patients undergoing a simulated public speaking test (SPST), which is a common anxiety testing method  Bergamaschi MM, Queiroz RH, Chagas MH, et al. Cannabidiol reduces the anxiety induced by simulated public speaking in treatment-naïve social phobia patients. Neuropsychopharmacology. 2011;36(6):1219-1226. . Compared to a placebo, CBD significantly reduced anxiety and discomfort in the participants with SAD. In fact, their reduced anxiety levels were comparable to those of the control participants.
Eight years later, a 2019 test compared the efficacy of three CBD doses (150 milligrams, 300 milligrams and 600 milligrams) and a placebo in men taking an SPST  Linares IM, Zuardi AW, Pereira LC, et al. Cannabidiol presents an inverted U-shaped dose-response curve in a simulated public speaking test. Revista brasileira de psiquiatria (Sao Paulo, Brazil : 1999). 2019;41(1):9-14. . Compared to a placebo, 300 milligrams of CBD significantly reduced participants’ anxiety during the speech, but the 150-milligram and 600-milligram doses did not. These results highlight how dosage can be highly variable and that more CBD isn’t necessarily more effective.
Meanwhile, another 2019 study tested CBD in much lower doses than most other clinical studies—some participants consumed 25 milligrams a day while others consumed 50 milligrams or 75 milligrams a day  Shannon S, Lewis N, Lee H, Hughes S. Cannabidiol in Anxiety and Sleep: A Large Case Series. Perm J. 2019;23:18-041. . Researchers thought higher doses might be too expensive for participants to maintain in their normal lives and that low doses would still prove effective. Indeed, anxiety decreased within the first month for most participants and remained low. Sleep quality also improved, although it fluctuated more than anxiety. Only three patients reported side effects.
CBD for Anxiety and Depression
In 2020, researchers tested the effects of CBD oil at varying doses across 397 patients with a variety of ailments  Gulbransen G, Xu W, Arroll B. Cannabidiol prescription in clinical practice: an audit on the first 400 patients in New Zealand. BJGP Open. 2020;4(1):bjgpopen20X101010. . Participants with non-cancer pain or mental health-related symptoms experienced significant improvement in anxiety and depression, as well as in their abilities to complete their usual activities. The use of CBD oil suggested significant pain relief in these groups as well.
CBD for PTSD and Phobia Therapy
A small 2019 study of 11 patients found that, when consumed orally and administered alongside routine psychiatric care, CBD decreased patients’ posttraumatic stress disorder (PTSD) symptom severity  Elms L, Shannon S, Hughes S, Lewis N. Cannabidiol in the Treatment of Post-Traumatic Stress Disorder: A Case Series. J Altern Complement Med. 2019;25(4):392-397. .
Other studies suggest CBD can reduce PTSD symptoms when consumed with THC  Bitencourt RM, Takahashi RN. Cannabidiol as a Therapeutic Alternative for Post-traumatic Stress Disorder: From Bench Research to Confirmation in Human Trials. Front Neurosci. 2018;12:502. . When taken together, the two compounds create what’s known as the “entourage effect,” where THC enhances the effects of CBD as CBD tempers the effects of THC, resulting in a more well-rounded experience  Ferber SG, Namdar D, Hen-Shoval D, et al. The “Entourage Effect”. Terpenes Coupled with Cannabinoids for the Treatment of Mood Disorders and Anxiety Disorders. Curr Neuropharmacol. 2020;18(2):87-96. .
Some studies also suggest CBD can enhance the effects of exposure therapy—which assists patients in dissociating certain cues with a fear response—and cognitive behavioral therapy  Das RK, Kamboj SK, Ramadas M, et al. Cannabidiol enhances consolidation of explicit fear extinction in humans. Psychopharmacology (Berl). 2013;226(4):781-792.  Blessing EM, Steenkamp MM, Manzanares J, Marmar CR. Cannabidiol as a Potential Treatment for Anxiety Disorders. Neurotherapeutics. 2015;12(4):825-836. .
How to Use CBD for Anxiety
Without clear FDA guidance, optimal CBD use for anxiety varies from person to person. You may find one method works better for you over another. You can consume CBD in the following forms:
- Oils and tinctures, which come in dropper bottles and are consumed by mouth
- Gummies, which are chewable, sweet and often fruit-flavored
- Sprays, which come in bottles with a nozzle to be sprayed in the mouth
- Capsules, softgels or tablets, which are taken individually by mouth like a pill
- Vapes, which heat CBD oil without igniting it, resulting in an inhalable vapor
- Flowers, which are dried hemp plants that are typically ignited and smoked
- Creams and gels, which introduce CBD topically (through the skin) as a more localized treatment
You may have to try different forms to determine what works best in addressing your anxiety. For instance, when it comes to the absorption of CBD in your bloodstream, vaping and smoking are more effective than edibles like gummies.
CBD Dosage for Anxiety
You also have to find the right CBD dosage for your anxiety. Experts suggest starting small and working your way up depending on how your body reacts.
Many clinical trials jump right to testing high doses. Successful doses evaluated for anxiety relief specifically include:
- 600 milligrams in patients with SAD in a speech simulation  Bergamaschi MM, Queiroz RH, Chagas MH, et al. Cannabidiol reduces the anxiety induced by simulated public speaking in treatment-naïve social phobia patients. Neuropsychopharmacology. 2011;36(6):1219-1226.
- 300 milligrams in male patients in a speech simulation  Linares IM, Zuardi AW, Pereira LC, et al. Cannabidiol presents an inverted U-shaped dose-response curve in a simulated public speaking test. Revista brasileira de psiquiatria (Sao Paulo, Brazil : 1999). 2019;41(1):9-14.
However, other trials suggest much lower doses are also quite effective in treating anxiety.
- 25 to 75 milligrams for generalized anxiety and/or sleep problems  Shannon S, Lewis N, Lee H, Hughes S. Cannabidiol in Anxiety and Sleep: A Large Case Series. Perm J. 2019;23:18-041.
- 33 to 49 milligrams a day for PTSD, in addition to routine psychiatric treatment  Elms L, Shannon S, Hughes S, Lewis N. Cannabidiol in the Treatment of Post-Traumatic Stress Disorder: A Case Series. J Altern Complement Med. 2019;25(4):392-397.
Another study involving hundreds of patients noted success with doses from 40 milligrams to 300 milligrams a day, further supporting the idea that CBD dosage varies significantly, depending on a person’s symptoms and physiology.
Potential Risks and Side Effects
The World Health Organization deems CBD a safe and generally well-tolerated substance. Studies report very few adverse effects, if any.
However, taking CBD while on other medications may pose a risk, as these substances may interact and cause unwanted effects, such as weight gain, drowsiness, upset stomach and change in appetite.
Cheryl Bugailiskis, M.D., a cannabis specialist at Heally, a telehealth platform for alternative medicine, also warns people with preexisting liver injuries and people taking medications that can cause liver injuries should practice caution when using CBD.
Prescription cbd oil for anxiety
Chris Aiken, MD
Editor-in-Chief of The Carlat Psychiatry Report. Practicing psychiatrist, Winston-Salem, NC.
Dr. Aiken has disclosed that he has no relevant financial or other interests in any commercial companies pertaining to this educational activity.
Your patient comes in with a new medication on his list: CBD oil. He started taking it for anxiety and wants to know if it’s safe. You hedge, explaining that there is limited information available on unregulated products, but the patient is persistent. He says CBD oil is available as a prescription, and wonders if you could write one for it.
Cannabidiol, or CBD, is a derivative of marijuana that has recently become available as a prescription drug, Epidiolex. It is FDA-approved for two rare forms of childhood epilepsy, Lennox-Gastaut and Dravet syndromes, and was fast-tracked for that indication because of the dire need for treatment in children with these intractable seizures. Meanwhile, the same drug has been available as a supplement for the past decade, called CBD oil. Many patients take this oil for its rumored mental health benefits, and you’ll need to know the basics when they request prescriptions for it.
Table: Cannabinoids From CBD to THC
CBD vs THC
Marijuana (cannabis) is a blend of over 100 cannabinoids, only one of which is tetrahydrocannabinol (THC), the cannabinoid that is most responsible for the high people get from consuming pot. CBD, on the other hand, does not cause a “high,” although many people consider it to be somewhat tranquilizing. CBD also does not cause some of the problems seen with THC, such as cognitive impairment, anxiety, and (more rarely) psychosis. Those dangers are particularly relevant to adolescents, where the latest data show that marijuana triples the risk of psychotic disorders (Jones HJ et al, JAMA Psych 2018;75(3):240–246). CBD has neuroprotective properties, and it may actually lower the risk of psychosis and anxiety with THC. For more information, see the table “Cannabinoids From CBD to THC” above.
CBD in psychiatric disorders
In one of the most paradoxical clinical findings in recent memory, it turns out that CBD, far from causing psychosis, may actually be an effective treatment for psychosis. So far, 5 out of 7 controlled trials of CBD’s antipsychotic effects have been positive, and the latest of these is reviewed in this issue (Epidemiol Psychiatr Sci 2018;27(4):327–335). Another prescription CBD product, Arvisol, is undergoing phase I clinical trials in schizophrenia.
In addition to psychosis, there are a couple of small, placebo-controlled trials of CBD in social anxiety disorder. These looked at the drug’s acute effects when taken before a stressful social situation in 34 subjects. Compared to placebo, CBD had a significant effect, bringing anxiety down to the same levels reported by healthy controls (Blessing EM et al, Neurotherapeutics 2015;12(4):825–836).
Somnolence is the main side effect with CBD, but studies in sleep are mixed. Tolerance can develop to its sedative effects, and low doses (below 160 mg) can be stimulating (Babson KA, Curr Psychiatry Rep 2017;19(4):23). CBD does not appear to help bipolar mania or the cognitive impairments of schizophrenia.
CBD oil or Epidiolex?
Are CBD oil and Epidiolex really the same drug? They are both CBD, short for cannabidiol, but where they differ is in their purity and regulatory status. Epidiolex is a Schedule V prescription drug, the lowest level of regulation for a controlled substance. CBD oil is an over-the-counter supplement. It is legal in all states as long as it’s extracted from the hemp plant, a variety of cannabis that contains little THC and produces no high.
In terms of purity, CBD oil is a gamble. In a study of 84 online products, only 30% contained the amount of CBD on the label, and 21% contained THC (Bonn-Miller MO et al, JAMA 2017;318(17):1708–1709). The FDA keeps a running tally of unacceptable products at www.fda.gov/NewsEvents/PublicHealthFocus/ucm484109.htm. Another good source is Consumer Labs, which tests products for purity and integrity. Among their recommended options, the best-priced oils are available at elixinol.com and bluebirdbotanicals.com.
The dosages used in psychiatric research range from 300 mg/day for anxiety to 800–1,200 mg/day for schizophrenia. The epilepsy dosage, 10–20 mg/kg/day, adds up to around the same amount used in schizophrenia for most adults. Cost is an issue with CBD, prescribed or not. A 300 mg dose is $20–50/day in the over-the-counter form and around $35/day for the prescription when paying out of pocket.
CBD, Marinol, and medical marijuana
CBD is in a very different category than dronabinol (Marinol) and nabilone (Cesamet), the other prescription cannabinoids. These are synthetic isomers of THC (Δ-9-THC) and are under tighter regulation than CBD (Schedule III vs Schedule V). They are only approved for nausea during chemotherapy and, in the case of dronabinol, anorexia in AIDS. As pure THC compounds without the protective effects of CBD, they may have even more psychedelic effects than marijuana (Bhattacharyya S et al, Neuropsychopharm 2010;35(3):764–774). “Medical marijuana” can refer to any marijuana component, such as CBD, or to the plant itself. It usually refers to the plant, which is legal with a prescription in 33 states and Washington DC. Each state has its own list of conditions that medical marijuana is approved for.
Side effects and drug interactions
The World Health Organization concluded that CBD has “a good safety profile” (WHO, 2018). Somnolence is its main side effect, and the PDR warns of elevated liver enzymes. On drug screens, CBD can cause a false positive for THC.
CBD may raise the levels of psychiatric medications through inhibition at UGT2B7 (lamotrigine, lorazepam) and CYP2C19 (diazepam and several SSRIs and antipsychotics). CBD itself is metabolized by CYP3A4 and CYP2C19.
Risks vs benefits
The FDA fast-tracked the approval of Epidiolex (CBD) because its risk-benefit profile is favorable for rare forms of epilepsy that are difficult to control with current anticonvulsants. The bar is higher for disorders with existing treatments, like psychosis and anxiety, and the data in these conditions are scarcer.
While we sort out these dilemmas, patients will no doubt experiment with the readily available CBD oil, so what should we do in the interim? We recommend the following commonsense approach.
TCPR Verdict: We don’t have much evidence to endorse or warn against CBD. Though it’s premature to prescribe CBD, we should guide patients to safer products if they are getting it on their own. That’s harm reduction, like suggesting to casual drinkers that red wine is safer than vodka