Can medical cannabis cause hallucinations?
6 min read
Sarah Sinclair
If you’re new to medical cannabis treatment, it’s natural to have concerns about its safety, particularly regarding its potential psychoactive effects. In this blog, we will address some of the questions around medical cannabis and hallucinations.
Contents
What is medical cannabis?
Medical cannabis refers to cannabis-based medicinal products (CBPMs) which are prescribed by clinicians for the treatment of a specific health condition. These products are subject to strict regulations and contain varying levels of cannabinoids, as well as other compounds such as terpenes which provide therapeutic benefits.
Only doctors on the General Medical Council (GMC) specialist register—consultants or ‘specialists’ such as neurologists, psychiatrists, and rheumatologists — are permitted to prescribe CBPMs.
Medical cannabis products primarily contain CBD (cannabidiol) and THC (tetrahydrocannabinol). They both come from the same plant but differ in their effects.
CBD
CBD is a non-psychoactive compound known for its calming and anti-inflammatory properties. It is not psychoactive and so does not produce the "high" associated with cannabis.
THC
THC is the psychoactive component of cannabis. In high doses it can cause euphoria, changes in perception, and in rare cases, hallucinations. However, in medical cannabis, this is less common as it is dosed precisely to minimise unwanted side-effects.
How does medical cannabis differ from recreational cannabis?
Unlike recreational cannabis, which is accessed through the illegal market, CBPMs are highly regulated and subject to strict manufacturing processes. Cultivation facilities which produce these must adhere to GMP guidelines for quality and safety reasons.
Recreational cannabis does not have this level of oversight to protect it from other harmful contaminants. It often contains high levels of THC and there is no clinician or healthcare professional involved.
What are the side-effects of medical cannabis?
As with any medication, medical cannabis can cause side-effects. Some of the most common side-effects of medical cannabis containing THC include:
- Lightheadedness
- Dry mouth
- Increased appetite
- Changes in mood (e.g. feeling more relaxed or socially withdrawn)
- Red eyes
- Racing heart beat or increased heart rate
- Changes in blood pressure (usually a slight increase)
- High doses of THC can sometimes induce feelings of anxiety, paranoia, or panic in some people
Can cannabis cause a person to have hallucinations?
In some cases, high doses of THC can cause hallucinations, but this is very unusual using medical cannabis when it is prescribed and accurately dosed.
Hallucinations are an extremely rare side effect of CBPMs, but there are some considerations which may make an individual more at risk.
Risk factors for cannabis psychosis
Some individuals are more sensitive to THC, even in low doses. Meanwhile, people with certain mental health conditions, such as schizophrenia or psychosis, may be at a higher risk of experiencing hallucinations or other adverse effects from THC.
It is important to discuss this with your specialist doctor before starting treatment with medical cannabis so they can determine whether it is appropriate for you.
What is cannabis psychosis like?
Cannabis psychosis may involve episodes of paranoia, confusion, hallucinations and delusions triggered by cannabis use. It varies in intensity and duration depending on factors such as dosage, individual sensitivity, and whether the cannabis was medically prescribed or recreationally used.
Symptoms can feel distressing but are typically only temporary. In most cases the effects subside within a few hours, although more serious cases particularly among individuals with underlying mental health conditions, may need medical intervention.
What happens if side-effects occur?
Patients receiving CBPMs are closely monitored, and if you experience adverse affects, your doctor can adjust your dosages or try you on different ratios of CBD to THC.
In the unlikely event that it should occur, there are some tips for how to stop cannabis psychosis, such as:
- Discontinue cannabis use immediately
- Move to a calm, quiet setting with supportive people to help reduce anxiety.
- Drink water and rest to help the body metabolise THC faster.
- If symptoms persist or worsen, seek medical help.
In some cases, CBD may help counteract the effects of the THC, but consult your doctor first before administering additional cannabis-based products.
How do medical cannabis clinics help minimise risks?
Medical cannabis is not a one-size-fits-all, so clinics like Releaf take several steps to ensure that treatment is prescribed and administered safely.
This includes carrying out thorough assessments of your medical history, current conditions, and any risk factors that could affect your response to cannabis prior to prescribing.
Prescribers will usually "start low, go slow". This means starting the patient on the lowest effective dose and gradually increasing under medical supervision to reduce the risk of side-effects.
CBPMs containing higher levels of CBD, or balanced ratios of CBD and THC, can also provide therapeutic benefits without significant psychoactive effects.
Who should avoid high-THC medical cannabis?
Even with precautions in place, there are some instances where a doctor may not recommend or prescribe CBPMs such as:
- In individuals with a personal or family history of psychosis or schizophrenia.
- Those who have experienced severe side effects from cannabis in the past.
- Those who are pregnant or breastfeeding
Final thoughts
If patients do encounter side effects with medical cannabis, they are generally classed as mild, and pass relatively quickly.
Hallucinations are extremely rare, and working with experienced professionals, such as Releaf’s team of specialist doctors, will further reduce the risk of unwanted side-effects.
If you or a loved one is considering medical cannabis treatment but still have questions or concerns, the team at Releaf is here to support you every step of the way. Visit the FAQs page or contact the patient support team here.
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It is important to seek medical advice before starting any new treatments. The patient advisors at Releaf are available to provide expert advice and support. Alternatively, click here to book a consultation with one of our specialist doctors.
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Sarah, a distinguished journalist with over a decade in publishing and communications, now excels in cannabis health and policy journalism in the UK, advocating for informed health decisions through her award-winning work.
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