Cannabis and Mental Health: Find the Right Products in the UK

Key Takeaways:

• Medical cannabis may be considered for certain mental health conditions when other treatments haven’t worked, but evidence is still early and results vary.

• To get a prescription, patients must be diagnosed and assessed by a specialist doctor, since NHS access remains limited.

• Cannabis affects people differently. The best form, strains, or terpenes depend on individual needs, and a specialist can help patients understand their options and find the right medical cannabis dose safely.

Medical cannabis is sometimes used for symptoms related to anxiety, depression, or PTSD. This is typically when standard treatments haven’t provided enough relief. Research on cannabis and mental health is still developing, and responses to THC and CBD can vary widely.

This guide explains what early research shows about cannabis and mental health, how patients access cannabis-based medicine, and how to talk with your specialist about different product options.

Does Cannabis Affect Mental Health?

Cannabis contains compounds like THC and CBD that interact with the body’s endocannabinoid system (ECS). This system may help regulate mood, stress, sleep, discomfort, and more. Because each person’s ECS works differently, cannabis can affect mental health symptoms in different ways.

Some people report feeling calmer or sleeping better when using cannabis, while others may feel more anxious. Current research includes small and observational studies, so more high-quality clinical trials are needed.

Cannabis and Anxiety

For anxiety, low doses of THC and CBD may help by calming the brain’s CB1 receptors. However, higher doses of THC may make anxiety worse for some people.¹ CBD-dominant products are often recommended since they may provide relief without the high.

Cannabis and Depression

THC may boost serotonin levels, which could improve mood, but high-THC strains can sometimes worsen symptoms for certain individuals.² CBD, on the other hand, has shown promise in easing depressive symptoms without the risk of intoxication.

Cannabis and PTSD

For PTSD, cannabis may help by reducing the intensity of traumatic memories and promoting relaxation. THC and CBD activate receptors in the brain’s fear and memory centres, which could reduce symptoms like nightmares and hypervigilance.³

Can Patients Get Medical Cannabis for Mental Health Conditions in the UK?

Since 2018, medical cannabis has been legal in the UK, but getting a prescription isn’t easy. Most patients who qualify go through private clinics because NHS prescribing is rare.

While it’s prescribed for conditions like epilepsy, chronic pain, and multiple sclerosis, it can also be an option for mental health conditions like anxiety, depression, and PTSD when other treatments haven’t worked and the physician believes it’s appropriate.

To get a prescription, a person must:

• Be diagnosed with a qualifying condition.
• Have tried other treatments without enough improvement.
• See a specialist doctor, who will decide if cannabis-based medicine is appropriate.

Cannabis-based medicine may be considered for conditions like anxiety, depression, or PTSD, but approval is not guaranteed. Specialists evaluate each case individually and review medical history, past treatments, and potential risks.

Can Cannabis Interact With Mental Health Medications?

Yes. CBD and THC can affect how the liver processes certain medications, which may change how strong a medication feels or increase the risk of side effects.

Examples include:

• Antidepressants. CBD may increase levels of SSRIs or tricyclics, which could lead to drowsiness or heart rhythm changes.⁴
• Antipsychotics. Medications like quetiapine or risperidone may be affected, increasing dizziness or sedation.⁴
• Beta-Blockers. CBD can raise levels of drugs like propranolol or metoprolol, potentially causing low blood pressure, dizziness, or fatigue.⁴
• Pain Medications. Drugs like tramadol or naproxen may be processed more slowly when combined with cannabinoids, increasing the risk of nausea or stomach problems.⁴

Always consult with a doctor before combining cannabis-based medicine with any medication. Never stop or adjust a prescribed medication on your own.

Flower, Edibles, Tinctures, and More

If a patient qualifies for cannabis-based medicine, their specialist doctor will help determine which form may be most appropriate.

Here are the basics:

Flower (Vaporised Only)

• Fast onset
• Must be vaporised, not smoked
• May require more frequent dosing

Edibles

• Long-lasting effects
• Slower onset
• Discreet and easy to use

Tinctures / Oils

• Can be taken under the tongue
• Easier to measure
• May last longer than inhaled forms

Capsules

• Measured doses
• Tasteless and discreet

Cartridges

• Portable and fast-acting
• Used with a vape pen

Your clinician will consider the best form for your needs based on your condition, preferences, and how your body responds to THC and CBD.

Choosing Cannabis Flower

Cannabis flower contains two main compounds: THC and CBD. THC can cause intoxication, while CBD does not. Some patients prefer products with lower THC and higher CBD, but responses vary.

Terpenes, the compounds that give cannabis its smell and taste, can also influence its effects. For example, some terpenes may feel relaxing, while others could feel more uplifting.

Medical cannabis flower is only approved for vaporisation, not smoking. Vaporising heats the flower gently, releasing the active compounds without burning them. The compounds are absorbed quickly through the lungs, allowing patients to titrate their dose to their tolerance more quickly. 

When prescribing cannabis, many physicians consider the terpene profile of the strain they recommend. Many patients find it helpful to keep a simple journal or record notes on their phone to track how different strains make them feel. This can help provide the physician with clues about which product works best.

Choosing Cannabis Capsules

Capsules provide consistent dosing and are easy to take. They contain measured amounts of cannabis oil and may be a good option for people who prefer a smokeless, discreet method.

Doctors consider the THC:CBD ratio when prescribing capsules, and patients may start with a low dose while their clinician monitors their response.

Choosing Cartridges

Cartridges contain cannabis oil and are used with a vape pen. They are discreet, portable, and fast-acting.

Patients should still be cautious with dosing because effects can be strong if inhaled quickly. A specialist doctor can explain how to use them safely and monitor side effects.

How to Find the Right Products at the Pharmacy

Medical cannabis is prescribed by a specialist doctor who will recommend the best product for your needs if you qualify. It’s still helpful to go into your consultation prepared. Here’s how to make the most of it:

Ask Questions

• What product or strain is best for my condition? 
• What’s the THC/CBD ratio, and how will it affect me? 
• Could it interact with my current medications?

Share Your Preferences

• Let your doctor know if you prefer oils, capsules, or flower. 
• Mention any concerns about dosing, side effects, or lifestyle needs.

Start Low, Go Slow

• Your doctor will likely start you on a low dose and adjust as needed. 
• Keep track of how you feel and share updates during follow-ups.

What We Know About Medical Cannabis and Mental Health

Researchers are still studying the impact of medical cannabis on conditions like anxiety, depression, and PTSD. Some patients report benefits, while others may not notice improvement or may experience stronger symptoms. 

Because responses vary, patients should consult with a doctor before exploring cannabis-based medicine and continue all prescribed treatments unless told otherwise.

Is Cannabis a Risk Factor for Psychosis?

Genetics are the main risk factor for psychosis. However, high-THC cannabis may worsen symptoms or trigger episodes in people who are already vulnerable.

Patients with a personal or family history of psychosis should speak with a specialist before using cannabis-based medicine.

Are There Potential Drawbacks Associated with Cannabis Use?

Heavy or frequent cannabis use may lead to cannabis use disorder (CUD). Withdrawal symptoms may include anxiety, irritability, mood changes, sleep problems, or reduced appetite. These symptoms may appear after stopping use, especially in regular users.⁵

A doctor can help monitor symptoms and provide guidance if withdrawal or dependence becomes a concern. Withdrawal symptoms like anxiety, irritability, and sleep issues may last up to two to three weeks.⁶ Doctors can help patients experiencing withdrawal.

Resources

1. Sharpe L, Sinclair J, Kramer A, de Manincor M, Sarris J. Cannabis, a cause for anxiety? A critical appraisal of the anxiogenic and anxiolytic properties. J Transl Med. 2020;18(1):374. Published 2020 Oct 2. doi:10.1186/s12967-020-02518-2

2. Feingold D, Weinstein A. Cannabis and Depression. Cannabinoids and Neuropsychiatric Disorders. 2020;1264:67-80. doi:https://doi.org/10.1007/978-3-030-57369-0_5

3. Nacasch N, Avni C, Toren P. Medical cannabis for treatment-resistant combat PTSD. Frontiers in psychiatry. 2023;13. doi:https://doi.org/10.3389/fpsyt.2022.1014630

4. Balachandran P, Elsohly M, Hill KP. Cannabidiol Interactions with Medications, Illicit Substances, and Alcohol: a Comprehensive Review. J Gen Intern Med. 2021;36(7):2074-2084. doi:10.1007/s11606-020-06504-8

5.  Connor JP, Stjepanović D, Le Foll B, Hoch E, Budney AJ, Hall WD. Cannabis use and cannabis use disorder. Nat Rev Dis Primers. 2021;7(1):16. Published 2021 Feb 25. doi:10.1038/s41572-021-00247-46.  Connor JP, Stjepanović D, Budney AJ, Le Foll B, Hall WD. Clinical management of cannabis withdrawal. Addiction. 2022;117(7):2075-2095. doi:10.1111/add.15743