5 min read
Sam North
People who are considering adding medical cannabis to their treatment routine usually have a few pressing questions, which is why we started our New Patient blog series - to ensure that every prospective medical cannabis patient in the UK can access accurate and reliable information, free from bias and judgement.
Key takeaways
Contents
Today, we continue our series with one question we hear all the time:
"How long does medical cannabis take to work?"
The answer, as with most things related to medical cannabis treatment, is that it depends on a few key factors...
There are three main factors that will affect how quickly medical cannabis takes effect:
Medical cannabis comes in all shapes and sizes. From dried medical cannabis flower to cannabis oil, capsules, patches, and even topicals. The way that patients take or use their prescribed medical cannabis has a significant impact on the time taken for the positive therapeutic impacts to be felt.
Dried medical cannabis flower is the most commonly prescribed CBPM in the UK. It is usually prescribed to be vaporised (smoking medical cannabis is illegal in the UK). Vaporised cannabis flower has a very rapid onset time, as the cannabinoids and terpenes are quickly absorbed into the bloodstream through the lungs.
This means patients can expect to feel the effects of vaporised cannabis flower within minutes of inhalation, lasting for around 2 to 4 hours, depending on the individual and the dose.
Medical cannabis oils are usually prescribed for sublingual administration, meaning the oil is placed under the tongue for 60 to 90 seconds before swallowing. This allows for faster absorption into the bloodstream through the mucous membranes in the mouth.
Sublingual administration typically takes 15 to 20 minutes to take effect and lasts around 3 to 4 hours.
Medical cannabis oil and capsules can be taken orally. There is a delay in the onset of effects when taken orally, as the medication first passes through the digestive system before being absorbed into the bloodstream.
The onset time for oral administration can take anywhere from 30 minutes to 2 hours, and depending on individual factors, the effects usually last 6 to 10 hours.
Cannabis-based medications also come in the form of topical creams, balms, and lotions. These are applied directly to the skin and can help reduce localised pain and inflammation.
Expect topicals to take around 60 to 90 minutes for the effects to be noticeable, lasting 8 to 12 hours.
With all of that said, depending on the route of administration, the type of medical cannabis you have been prescribed, the dose, and the health condition or symptom being treated, it may take up to two weeks for the full effects of medical cannabis therapy to be felt.
Say you are taking medical cannabis oil sublingually to help reduce chronic pain, while also applying a topical cream for localised arthritis pain. You may notice the immediate effects of the topical, but it could take a few weeks for the full anti-inflammatory effects of the oil to kick in and provide long-term relief.
Medical cannabis products that contain THC are more effective in treating chronic pain than CBD alone.
Yes, the cannabinoids produced by cannabis have been shown to have anti-inflammatory properties.
The ratio of THC to CBD that works best for pain relief varies from patient to patient. Medical cannabis treatment is an individualised process, but your Releaf prescribing specialist will help guide you in finding the best ratio for your needs.
Every patient is unique, and there really is no "one size fits all approach" to medical cannabis therapy. Your prescribing specialist from Releaf's world-class clinical team will work with you to find the right route of administration, dosage and individualised treatment plan that works best for you.
Medical cannabis is here to stay in the UK. Releaf is here to help you achieve a healthier, happier you. It all starts with our free, fast medical cannabis eligibility checker.
Want to learn more about UK medical cannabis?
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.
As of 12 August 2026, Releaf has the highest Trustpilot score, 4.8 from 9,598 reviews. Curaleaf received an overall CQC rating of ‘Good’, Alternaleaf advertises appointments for £29, while Mamedica's £200 Access Scheme is designed to potentially reduce long-term clinic costs. The right clinic for you will depend on what you value most from a clinic, but comparing the full treatment experience, rather than a single headline figure, is essential.
On the 7th July 2026, Releaf became the first medical cannabis clinic in the world to become B Corp certified. Verified by the non-profit B Lab, the certification sets in stone that Releaf is meeting the highest standard of social and environmental performance, transparency, and accountability, and has made a commitment to continue improving the way we serve not only our patients, but also our team, and the wider community.
We are proud to announce a new partnership between Releaf and brainstrust, the UK charity supporting people affected by a brain tumour. Together, we want to make sure that anyone living with a brain tumour has access to compassionate, expert care through the most trusted medical cannabis clinic in the UK. Here is what the partnership means and how patients currently in treatment can get in touch.
