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.

Generalised Anxiety

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 care16 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
  • restlessness
  • fatigue
  • 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
600mg11 Social anxiety disorder before a simulated public speaking test
300mg31 Anxiety before a simulated public speaking test
25 to 75mg17 Generalised anxiety and/or sleep problems
33 to 49mg per day16 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
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 blood34 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?

Side Effects

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
  • fever
  • 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.


More information



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