What is Ulcerative Colitis?
Ulcerative colitis is a type of inflammatory bowel disease (IBD). It happens when the body’s own immune system attacks the lining of the large bowel by mistake. This causes inflammation and small sores, called ulcers, to form.
The condition usually starts in the rectum, which is the last part of the bowel. In some people, it stays only in the rectum. In others, it can spread to part or all of the large bowel.
How much of the bowel is affected, and how badly, varies from person to person. The exact cause is not fully known. It is thought to be linked to a mix of genes, the environment, and how the immune system responds.
Ulcerative Colitis and Medical Cannabis: The Facts
What Causes Ulcerative Colitis?
Doctors do not know exactly why some people get ulcerative colitis. It seems to be caused by a mix of three things: a person’s genes, their surroundings, and how their immune system reacts in the gut.
Genes appear to play a part. Around 10–20% of people with ulcerative colitis have a close family member who also has some form of IBD [3]. This does not mean a child of a parent with ulcerative colitis will definitely get it. It just means the chance is a bit higher than for the general population.
What are the Symptoms of Ulcerative Colitis?
Symptoms can vary depending on how much of the bowel is affected and how severe the inflammation is. Most people have times when symptoms are worse, called flare-ups. They also have times when symptoms get better or go away, called remission.
The most common symptoms in the bowel are:
- Diarrhoea
- Blood mixed in with bowel motions
- Tummy pain
- Pain on passing a bowel motion
- Periods of constipation
- Loss of weight
- Extreme tiredness
- Anaemia (which may cause pale skin or shortness of breath)
Some people also have symptoms outside the bowel. These can include:
- Joint pain or swelling
- Back pain
- Skin problems (such as rashes)
- Eye inflammation (redness or pain)
- Bone thinning (osteoporosis)
- Liver or bile duct conditions
People with ulcerative colitis may also have a higher risk of bowel cancer. Because of this, a specialist may suggest regular check-ups using a camera test called a colonoscopy.
What is the Difference Between the Symptoms of Ulcerative Colitis and Crohn’s Disease?
Ulcerative colitis and Crohn’s disease are both types of inflammatory bowel disease (IBD), but they affect the digestive system in different ways.
Ulcerative colitis only affects the large bowel. Crohn’s disease can affect any part of the gut, from the mouth all the way down to the bottom.
Both can cause diarrhoea, tummy pain and weight loss. This can make them tricky to tell apart at first. Specialist tests such as blood tests, scans, and a camera test called an endoscopy can help to confirm which one a person has.
How is Ulcerative Colitis Diagnosed?
Doctors use a few different tests to look for inflammation and to rule out other causes. These usually include:
- Blood tests, to look for signs of inflammation or anaemia
- Stool samples, to check for inflammation and exclude infection
- Scans, such as MRI or CT scans, to assess the bowel
The most accurate way to confirm a diagnosis is usually through a colonoscopy or flexible sigmoidoscopy. These procedures involve passing a thin, flexible tube with a camera into the bowel to examine the lining.
During the procedure, small samples of tissue (biopsies) may be taken and examined under a microscope to help confirm the diagnosis.
What are the treatment options for ulcerative colitis?
Treatment for ulcerative colitis focuses on controlling inflammation, managing symptoms, and maintaining periods of remission (when symptoms are under control).
This is often approached in two stages:
Treating flare-ups
When symptoms get worse, treatment often starts with anti-inflammatory medicines. In some cases, a short course of steroids or other immune-calming medicines may be used. The aim is to bring inflammation down quickly.
Maintaining remission
Once symptoms are under control, ongoing treatment is usually needed to help prevent flare-ups. This often follows a stepwise approach, starting with anti-inflammatory medications and adding other treatments if needed.
For people with moderate to severe ulcerative colitis, additional options may include:
- Immunosuppressant medications
- Biologic therapies (targeted treatments that act on the immune system)
- Surgery, in some cases
Where Medical Cannabis May Fit
Medical cannabis does not treat ulcerative colitis itself. In the UK, it can be considered for some patients whose symptoms have not been well controlled by at least two standard treatments. It is always prescribed alongside, not instead of, the usual specialist-led care.
Medical cannabis may be considered to help manage some symptoms that can come with ulcerative colitis, such as:
- Chronic abdominal pain or cramping
- Sleep disturbance, often related to pain or night-time symptoms
- Reduced appetite
- Nausea
- Inflammation
Whether medical cannabis is a suitable option for any one person is for a specialist to decide. The decision is based on the patient’s history, current symptoms and treatment so far.
How does Ulcerative Colitis Affect Daily Life?
Ulcerative colitis can affect more than just the gut. Symptoms like tiredness, weight loss and joint pain can make work, exercise and family life harder.
Living with the condition can also affect social life. Some people feel they need to stay close to a toilet. This can make travelling, eating out, or playing sport more difficult. Many people find that planning meals and trips ahead of time helps.
Flare-ups are unpredictable. Not knowing when symptoms might come back can lead to stress or anxiety. Some people may avoid certain places or events because they worry about symptoms getting worse without warning.
Many treatments are available, but they do not work well for everyone. Some people keep having symptoms even after trying several options. For these people, a specialist may discuss whether medical cannabis could be considered.
You can read more about the experiences of patients at Curaleaf Clinic on our testimonials page.
Medical cannabis and Ulcerative Colitis: a brief overview
Since 2018, medical cannabis has been a legal prescription option in the UK for some patients. Only specialist doctors can prescribe it. It is usually only considered when at least two other treatments have not given enough symptom relief.
Medical cannabis works on a system in the body called the endocannabinoid system. This system helps to control things like pain, mood, appetite and the immune response. It is found throughout the body, including in the gut.
Cannabis-based medicines contain active substances called cannabinoids. The two most studied are tetrahydrocannabinol (THC) and cannabidiol (CBD). The right balance of these depends on the patient and the symptoms being looked at.
- THC interacts mainly with CB1 receptors in the brain and nervous system. It is a substance that has been studied in relation to pain, sleep and appetite.
- CBD interacts with different parts of the endocannabinoid system. It is being studied in relation to inflammation and how pain is felt. [3].
Medical cannabis is not suitable for everyone. Whether it could be an option for a particular person is a clinical decision made by a specialist after a full assessment.
What Does the Research say About Medical Cannabis and Ulcerative Colitis?
Research into medical cannabis for ulcerative colitis is still at an early stage. Most studies look at inflammatory bowel disease as a whole, rather than ulcerative colitis on its own. The number of patients in these studies is small. Most studies are observational, which means they record what happens to patients but cannot prove cause and effect.
One example is from our The UK Medical Cannabis Registry. This is a database that collects real-world information from patients in the UK who have been prescribed medical cannabis. An analysis of 76 patients with IBD reported on changes in quality of life, anxiety and sleep over a year of treatment [4].
Findings of this kind give a useful early picture, but they are not the same as evidence from randomised clinical trials. More research, across different study types, is needed before clearer conclusions can be drawn for ulcerative colitis.
Can I be Prescribed Medical Cannabis for Ulcerative Colitis?
If you live with ulcerative colitis and still have symptoms despite trying other treatments, medical cannabis is one option you could discuss with a specialist.
At Curaleaf Clinic, you can start with a short eligibility assessment to see if you can be booked in for a consultation. A specialist will review your medical records and confirm whether you can proceed.
If a consultation is right for you, you will meet a specialist consultant. Together you will go through your medical history, your current symptoms, and what you hope to get from treatment. The consultant will then advise whether medical cannabis could be a suitable option.
References
[1] NHS (n.d.) Ulcerative Colitis. Available at: https://www.nhs.uk/conditions/ulcerative-colitis/
[2] National Institute of Diabetes and Digestive and Kidney Diseases (n.d.) Definition & Facts of Ulcerative Colitis. Available at: https://www.niddk.nih.gov/health-information/digestive-diseases/ulcerative-colitis/definition-facts
[3] Childers RE, Eluri S, Vazquez C, Weise RM, Bayless TM, Hutfless S. Family history of inflammatory bowel disease among patients with ulcerative colitis: a systematic review and meta-analysis. J Crohns Colitis. 2014 Nov;8(11):1480-97. doi: 10.1016/j.crohns.2014.05.008. Epub 2014 Jun 26. PMID: 24974207.
[4] Gupta A, Erridge S, Graf V, Kelada M, Bapir L, Jesuraj N, Warner-Levy J, Clarke E, McLachlan K, Coomber R, Rucker JJ, Platt MW, Sodergren MH. UK medical cannabis registry: an updated analysis of clinical outcomes of cannabis-based medicinal products for inflammatory bowel disease. Expert Rev Gastroenterol Hepatol. 2024 Dec;18(12):829-838. doi: 10.1080/17474124.2024.2443574. Epub 2025 Jan 9. PMID: 39689344.
