Gastrointestinal
Aminosalicylates
Mesalazine (5-ASA) and related drugs — The mainstay for mild-to-moderate ulcerative colitis — to treat flares and maintain remission.
Education and reference only. This is a plain-language class overview — it deliberately contains no doses. Always check the current Summary of Product Characteristics (SmPC), the BNF and your local formulary before prescribing or administering any medicine.
What it is
Aminosalicylates are anti-inflammatory drugs that act directly on the lining of the bowel. They are the standard treatment for mild-to-moderate ulcerative colitis, both for flares and for long-term maintenance.
How it works
Delivered to the gut lining, the active component (5-aminosalicylic acid) calms local inflammation in the colon. Different formulations and delivery systems are designed to release it at the right place and rate along the bowel.
In practice
In practice aminosalicylates (chiefly mesalazine) are the backbone of treatment for ulcerative colitis: used to settle a flare and, importantly, taken continuously to maintain remission, where they also appear to reduce the long-term risk of bowel cancer. Adherence matters, and because different preparations release the drug in different parts of the bowel and at different rates, brands are generally not freely interchangeable. Combining oral with topical (suppository or enema) treatment often works better for disease lower down. They are usually well tolerated; the points to watch are renal function (a rare kidney inflammation can occur, so it is checked periodically) and, rarely, blood disorders — so unexplained bruising, bleeding or sore throat should be reported. They are far less central in Crohn's disease than in ulcerative colitis.
Examples
Practical use
How to take it & use it well
- Take mesalazine regularly as prescribed, even when your bowel symptoms have settled, because it works mainly to keep ulcerative colitis in remission.
- Swallow modified-release or coated tablets and granules whole as directed, and do not crush or chew them so the medicine reaches the right part of the bowel.
- If you use granules, take them as instructed, often placed on the tongue and washed down without chewing.
- For suppositories or enemas, follow the technique your team shows you, ideally using them at bedtime so the medicine stays in contact longer.
- Stay well hydrated and tell your team if you notice unexplained bleeding, bruising, sore throat or fever, which should be checked.
- Stick to the same brand your prescriber chose, as different mesalazine products release the drug differently and are not always interchangeable.
Common uses
- Mild-to-moderate ulcerative colitis (flares and maintenance)
- Maintenance to sustain remission
- Sulfasalazine also in rheumatoid arthritis
Monitoring
- Renal function periodically
- Symptom control and maintenance of remission
- Full blood count if blood-disorder symptoms occur
Weighing it up
Advantages & disadvantages
Advantages
- Helps keep mild to moderate ulcerative colitis in remission, reducing flare-ups when taken regularly.
- Can ease an active flare of ulcerative colitis, especially when oral and rectal forms are combined.
- Generally well tolerated for long-term use compared with steroids.
- Available in several forms, including tablets, granules, suppositories and enemas, to target different parts of the bowel.
Disadvantages
- Needs to be taken consistently, and stopping when you feel well can allow the condition to flare.
- Different brands are not always interchangeable, so switching without advice can affect how well it works.
- Can rarely affect the kidneys, so your team checks kidney function from time to time.
- May cause side effects such as headache, nausea, tummy pain or, rarely, blood-count changes that need monitoring.
Key safety principles
What to watch for
- Rare kidney inflammation — renal function is checked periodically.
- Rare blood disorders — report unexplained bruising, bleeding, sore throat or fever.
- Preparations are not freely interchangeable; sulfasalazine can cause reversible reduced fertility in men and additional sulfonamide effects.
Key interactions
What to avoid or check alongside
- Combining mesalazine with other medicines that can affect the kidneys, such as some anti-inflammatory painkillers, may add to kidney risk.
- Mesalazine may increase the effect of azathioprine and mercaptopurine on the blood count, so monitoring is important.
- It can slightly affect how some other medicines, such as certain blood thinners, work, so report any unusual bleeding.
- Other medicines that lower the blood count should be used with care alongside mesalazine.
- Always tell your pharmacist about all medicines and supplements you use.
Patient & carer advice
- Keep taking it even when well — it maintains remission and protects the bowel
- Stay on the same preparation unless we advise otherwise
- Report unexplained bruising, bleeding or a sore throat with fever
Use with
Related clinical calculators
Dose and risk decisions for this class often depend on renal function, weight or bleeding/stroke risk. These tools help:
Answers
Aminosalicylates: frequently asked questions
Should I keep taking mesalazine when I feel well?
Yes. Mesalazine works mainly to keep ulcerative colitis in remission, so it is usually taken long term. Stopping when symptoms settle makes a flare more likely.
Can I switch between mesalazine brands?
It is best not to switch without advice. Different brands release the medicine in different ways and at different points in the bowel, so they are not always interchangeable and switching can affect control.
Why does mesalazine need kidney checks?
Rarely, mesalazine can affect kidney function. Your team usually checks your kidneys before starting and periodically afterwards to make sure the medicine continues to be safe for you.
What symptoms should I report on mesalazine?
Tell your team about unexplained bruising or bleeding, sore throat, fever, or signs of kidney trouble such as a big change in how much you pass urine, so they can check your blood and kidney tests.
Authoritative sources
Always verify against the source
This overview is for orientation. For doses, interactions, contra-indications and the full monograph, use:
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