What is THC?
THC is the main psychoactive compound in cannabis that interacts with the endocannabinoid system to produce therapeutic effects. Understanding THC is important for patients considering medical cannabis, as it influences both symptom relief and potential side effects.
If you've been looking into medical cannabis, you've probably come across the term 'THC' more than once. It's one of those things that seems to come up everywhere - in news articles, on product labels, and even in conversations with doctors - but what actually is it?
Well, THC stands for tetrahydrocannabinol. It's the main compound in cannabis that causes the 'high' people associate with recreational use. But there's a lot more to THC than that, especially when it comes to treatment for a range of different medical conditions. For patients considering medical cannabis through Medicann, understanding what THC does, how it works, and whether it's right for you is an important part of making an informed decision.
In this blog, we explain what THC is, how it differs from CBD, and what role it plays in medical cannabis prescriptions in the UK.
What's the difference between CBD and THC?
Both THC and CBD are cannabinoids - natural compounds found in the cannabis plant. They interact with the body's endocannabinoid system, which helps regulate things like pain, mood, sleep and appetite.
THC is psychoactive, which means it can alter your mood, perception and mental state. It's the compound responsible for the feeling of being high. CBD, on the other hand, is not psychoactive. This means, it won't make you feel intoxicated, though it may have calming or relaxing effects for some people.
When it comes to medical use, both have their place. Some patients respond better to CBD-dominant products, while others find THC-containing medicines more effective for their symptoms.
At Medicann, our process is simple. Our specialist doctors will consult with you to assess your condition and medical history to decide which type of product might work best for you. Every prescription is tailored to the individual, and that includes the balance of THC and CBD in the medicine.
Is THC legal?
This is one of the most common questions patients ask, and it's understandable why. Cannabis is still a Class B controlled substance in the UK, which means possessing or supplying it without proper authorisation is illegal. But THC itself isn't automatically illegal in every situation.
When THC is prescribed as part of a cannabis-based product for medicinal use, it is legal. That means if you receive a prescription from a specialist doctor through a clinic like Medicann, you are allowed to possess and use THC-containing medicine as prescribed. The key is that it must be prescribed legally and supplied through approved medical channels.
It's also worth noting that not all cannabis products are the same. Over-the-counter CBD products are widely available in shops and online, but these must contain less than 0.2% THC to be sold legally in the UK. Medical cannabis products prescribed through Medicann can contain higher levels of THC, but only because they are prescribed by a doctor and dispensed through regulated pathways.
In short, THC is legal when it's part of a legitimate medical prescription. Growing cannabis at home or buying THC products without a prescription remains illegal in the UK.
Is THC addictive?
It's a fair question, and one that deserves an honest answer. THC can be habit-forming for some people, particularly if used recreationally in large amounts over a long period. However, according to the independent Scientific Committee Drug Science UK, the risk of physical dependence is lower than with substances like nicotine, alcohol or opioids.
When THC is used as part of a medical treatment plan, the risk is managed through careful prescribing and regular follow-up. At Medicann, patients are monitored throughout their treatment. An approved doctor will review how the medicine is working, adjust doses if needed, and check in on any side effects or concerns. This level of support helps ensure that THC is used safely and appropriately.
Most patients using medical cannabis do not develop problematic use, especially when they're following a prescription tailored to their needs. If you have concerns about dependency or past experiences with cannabis, it's important to discuss this openly during your consultation.
How long does THC stay in your body?
The length of time THC stays in your system depends on several factors, including how much you've used, how often, and your individual metabolism. According to Talk To Frank (formerly National Drugs Helpline), for most people, THC can be detected in urine for up to a few days after a single use, or up to several weeks for regular users. In blood, it typically clears within a few hours to a couple of days.
It's worth knowing this if you're in a job that involves drug testing, or if you're concerned about driving. Even though you may have a legal prescription, THC can still show up on a test, and it's your responsibility to inform employers or authorities if required. Medicann provides patients with documentation to show they are using prescribed medication legally.
Can THC affect medication?
Yes, THC can interact with certain medications. It may affect how your body processes drugs that are broken down by the liver, including some blood thinners, antidepressants and epilepsy medications. That's why it's so important to give a full and accurate medical history during your consultation.
Our approved GPs will review any medications you're currently taking and assess whether medical cannabis is safe to use alongside them. If there are potential interactions, they may adjust your treatment plan or recommend closer monitoring. This is another reason why medical cannabis should always be prescribed by a qualified doctor, not bought from unregulated sources.
Does THC have any medical benefits?
Yes. While THC is often associated with recreational use, it also has recognised medical properties. Research and clinical experience suggest that THC may help with chronic pain, muscle spasticity, nausea, and appetite loss. It's also being studied for conditions like migraines, IBS and neurological conditions such as epilepsy.
For some patients, THC offers relief where other treatments have not worked. That said, it's not a one-size-fits-all solution. Some people respond well to it, while others may experience side effects like dizziness, drowsiness or changes in mood. This is why the consultation process at Medicann is so important - it allows the doctor to assess whether THC is likely to be helpful and appropriate for your specific situation.
Does medical cannabis contain THC in the UK?
It can, yes. Medical cannabis products prescribed in the UK may contain THC, CBD, or a combination of both. The exact formulation depends on what the doctor believes will be most effective for the patient's condition.
At Medicann, our approved doctors will decide whether a THC-containing product is suitable based on your symptoms, medical history and treatment goals. Some patients are prescribed CBD-dominant products, others receive balanced formulations, and some may be prescribed products with higher levels of THC. Every prescription is individual.
All cannabis-based medicines prescribed through Medicann are sourced through regulated suppliers and meet strict quality standards. You won't receive anything that isn't safe, legal and appropriate for medical use.
If you're curious about whether medical cannabis - and THC specifically - might be right for you, the first step is to check your eligibility online. From there, you can book a consultation with one of Medicann's GMC-registered specialists and get clear, honest advice tailored to your needs using our app.
Get in touch today to find out more.