Mesalazine

Mesalazine: Long-Term Therapy That Works — Even When You Feel Well

Mesalazine (5-aminosalicylic acid) is the basic medicine in ulcerative colitis and works against inflammation directly in the lining of the bowel, not throughout the whole body as cortisone does. What decides the outcome is the right dosage form: tablets, suppositories, enemas and foams each reach different sections of the bowel. The commonest reason for a new flare is stopping the treatment on your own during symptom-free phases.

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Contents

  1. At a Glance: Technical Data Sheet
  2. How it works: locally in the lining instead of throughout the body
  3. The dosage form decides the outcome
  4. Dosing and use in everyday life
  5. Side effects and what helps against them
  6. Carrying on when nothing hurts: maintenance therapy
  7. Kidney values and checks over time
  8. Interactions: azathioprine, NSAIDs and more
  9. Mesalazine in Crohn's disease: an honest assessment
  10. Cortisone is for the flare, not for the long run
  11. Special situations: pregnancy, children, travel, diet
  12. Mesalazine experiences: what patients really ask
  13. FAQ: Common questions about mesalazine

1. At a Glance: Technical Data Sheet

PropertyDetails
Active ingredientMesalazine (5-aminosalicylic acid, 5-ASA for short)
ATC codeA07EC02
Drug classA locally acting anti-inflammatory preparation for the bowel (aminosalicylate)
Dosage formsProlonged-release tablets and granules, suppositories, enemas and rectal foam
Half-lifeA few hours for the part that is absorbed — what counts is not the blood level but the concentration at the lining
Maximum daily doseVaries from preparation to preparation, markedly higher in a flare than in maintenance; the treating practice sets it
Onset of effectIn a flare as a rule over days to a few weeks; the preventive effect only develops over months
Prescription statusPrescription-only medicine
Notable featureOn current knowledge, consistent long-term treatment also lowers the risk of bowel cancer in ulcerative colitis
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2. How it works: locally in the lining instead of throughout the body

Mesalazine is the basic medicine in ulcerative colitis — both in a flare and in the symptom-free time.¹,² To understand why it is used in such a distinctive way, it helps to look at where it acts.

Unlike prednisolone and other cortisone preparations, mesalazine does not work through the bloodstream across the whole body but directly at the inflamed lining of the bowel: there it damps down the formation of inflammatory messenger substances and mops up aggressive oxygen radicals. Only a small part reaches the blood — and that part contributes little to the effect, but it does contribute to the few systemic side effects.

Three things follow from that which shape the whole handling of mesalazine:

  • The drug has to arrive. A locally acting medicine has to reach the inflamed site — and that is exactly what the various dosage forms achieve (section 3).
  • It has no cortisone side effects. No moon face, no bone loss, no suppression of the adrenal glands. That is why mesalazine is suitable for long-term treatment — and cortisone is not.
  • You cannot feel it working. You notice the preventive effect by the fact that nothing happens — which makes sticking with it the real challenge (section 6).
5-ASA, sulfasalazine, mesalazine — what is the difference? The active part is always 5-aminosalicylic acid. The older predecessor sulfasalazine couples it to a sulfonamide carrier, which caused many of the side effects that used to be typical. Mesalazine manages without that carrier and is therefore usually preferred today.

3. The dosage form decides the outcome

This is the point that is missing from the package leaflet and makes the biggest difference in practice: with mesalazine the dosage form often decides the outcome more than the dose does. A high tablet dose that never reaches the inflamed rectum is inferior to a correctly placed small dose.

Which form suits you depends on how far the inflammation extends in the large bowel. This extent is established at colonoscopy and is stated in your report.

ExtentSuitable formWhy
Proctitis — the rectum onlySuppositoriesThey release the drug exactly where the inflammation is — the form of choice according to the guideline
Left-sided colitis — as far as the left bend of the large bowelAn enema or rectal foam, usually plus tabletsThey travel further up than a suppository and cover the left-sided section
Extensive colitis — beyond the left bendProlonged-release tablets or granules, often plus rectal useOnly the oral form reliably reaches the sections higher up
Symptom-free phaseThe form that worked in the flare — usually at a lower doseMaintenance follows the anatomy, not how you feel
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An important point from the guidelines: the combination of oral and rectal use is more effective than oral treatment alone in left-sided and extensive disease.² And yet the rectal form is the one most often left out in everyday life — because it is unpleasant, or because nobody has explained it.

Three things make rectal use markedly easier. First: use it in the evening, directly before going to sleep — lying down, the drug stays where it belongs. Second: go to the toilet beforehand, which lengthens the time it stays in considerably. Third: many people find foam more pleasant than liquid enemas — if enemas do not work for you, ask about it instead of giving up rectal treatment altogether.

The oral form also comes in several variants: with a pH-dependent coating, with time-delayed release or as a multi-matrix system. They differ in which section of the bowel the drug is released in. That is why mesalazine preparations are not freely interchangeable, even when the active ingredient and the number of milligrams look the same. If your pharmacy swaps the preparation because of a rebate contract with your health insurer, a quick query is worth it — see generics vs brand-name medicines.

4. Dosing and use in everyday life

The figures below describe what the SmPC and the guideline give as the usual approach. They are not a dosing instruction — the dose, the form and the duration are set by the treating practice.

  • Flare and maintenance: a markedly higher daily dose in a flare, often oral and rectal combined; in maintenance a lower dose, but permanently — as a rule over years.
  • Once or several times a day: on current evidence a single oral dose is at least as effective as several individual doses — and it is kept up more reliably.²
  • Do not break up prolonged-release forms: the coating controls where the drug is released — split or crushed, it ends up in the wrong place (see splitting tablets). And drink enough, particularly with granules.
  1. Choose a fixed time of day. Tie the oral dose to an existing routine — breakfast, brushing your teeth, coffee. The basics are in the guide how to take medications.
  2. Rectal use in the evening, directly before going to sleep and after a trip to the toilet. Granules are placed on the tongue and washed down with plenty of fluid, not chewed.
  3. A missed dose is as a rule made up if the timing still allows it; a double amount is not the answer (see missed a medication). And order your next supply early: a gap in long-term treatment usually arises not out of conviction but because the prescription was missing.

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5. Side effects and what helps against them

Mesalazine counts as one of the better tolerated long-term medicines. Most complaints are mild and appear in the first few weeks.

Common and usually mild

  • Headaches — the most frequently reported side effect, often temporary.
  • Nausea, wind and abdominal pain — hard to tell apart from the underlying illness.
  • Skin rash and itching — usually harmless, but they should be reported.
  • Local irritation with rectal use — burning or a cramping feeling directly after insertion, which as a rule settles.

Rare, but important to know about

  • Impaired kidney function: very rare, but the clinically most significant side effect — above all an interstitial nephritis. At first it causes no complaints and is only picked up through blood values. Hence the checks in section 7.
  • Changes in the blood count: rare; the warning signs are unusual bruising, frequent infections and a sore throat with fever.
  • Inflammation of the pericardium or the heart muscle: a rarity, which can show itself through chest pain, breathlessness or fluttering of the heart and needs assessing immediately. Likewise rare: raised liver values and inflammation of the pancreas.
The paradoxical worsening — rare, but treacherous. In a few cases mesalazine makes the colitis worse instead of better: more diarrhoea, cramps, sometimes blood in the stool — shortly after starting or after a dose increase. It looks like a flare and is therefore often answered with a higher dose, which makes it worse. Raise this connection actively, but do not stop anything on your own.
Get this assessed by a doctor straight away. If you are passing markedly less urine, if you are retaining fluid, if you have a persistent fever with no recognisable infection, chest pain or breathlessness, seek medical help at short notice — with acute chest pain and breathlessness, call 112 (emergency services in Germany). Report unusual reactions afterwards, see side effects of medications.

6. Carrying on when nothing hurts: maintenance therapy

Mesalazine has two jobs: to end the flare and to prevent the next one. The second is the more important — and the one that fails in everyday life.

The reason is psychologically understandable: in the symptom-free phase there is no feedback — no pain, no blood, no diarrhoea. If you leave the medicine out, you notice nothing for weeks and conclude from that that it was not needed. The flare comes later and then seems to come out of nowhere.

Stopping on your own is the commonest avoidable trigger of a flare. Studies of adherence in ulcerative colitis agree that a considerable proportion of those affected do not keep up maintenance therapy in symptom-free phases — and that breaking it off goes with a markedly higher risk of relapse.²,³ Stopping is therefore something to talk about, not to go it alone on: a reduction can be justifiable, but that decision needs your findings and the course of your illness. How to approach it in a structured way is described in the guide stopping medications.

The second argument: the risk of bowel cancer

Long-standing ulcerative colitis raises the risk of cancer of the large bowel — particularly with extensive disease and persistent inflammation. On current knowledge, consistent long-term treatment with mesalazine lowers this risk, presumably above all because it suppresses the chronic inflammation.² The evidence comes predominantly from observational studies and is therefore less robust than a randomised trial — that belongs to an honest assessment. But it remains an argument that the guidelines expressly make and that most of those affected never have explained to them. Together with the surveillance colonoscopies, that gives a simple message: the tablet you take in the symptom-free time is working on something you cannot feel — and therefore needs outward structure rather than motivation.

How brite makes it workable. Enter both forms separately in your digital medication plan — the tablet in the morning, the suppository in the evening. The reminder works even when you are feeling well, and at your next appointment your health record shows how complete your maintenance has been. That counts for a lot, particularly when the question is whether the treatment has to be changed. More on this under chronic illness in everyday life.

7. Kidney values and checks over time

Mesalazine is well tolerated, but it is not free of checks. The most important one concerns kidney function: kidney damage caused by mesalazine is rare, runs for a long time without any complaints and is more reversible early than late. That is exactly why it is measured although you are feeling well.¹,²

  • Before treatment starts: baseline values for kidney function (creatinine, eGFR), the blood count and liver values.
  • Over time: closer together in the first few months, because kidney reactions typically occur early; after that regularly, usually at least once a year.
  • And as the occasion arises: with feverish infections, with a heavy loss of fluid, with new painkillers or if you keep on feeling different.

What to look for on the laboratory sheet is explained in the guide understanding blood values. If kidney function is already impaired, special rules apply — background under chronic kidney disease and medications for kidney and liver disease.

Two further values often play a part in ulcerative colitis: chronic blood loss through the bowel frequently leads to iron deficiency anaemia with tiredness and a drop in performance. And the stool marker calprotectin often shows inflammation in the bowel before you can feel it — the counterpart to the feeling of being free of complaints.

8. Interactions: azathioprine, NSAIDs and more

Mesalazine has comparatively few interactions — hardly any of it is absorbed into the body as a whole. The ones that do matter are all the more important to know about.

CombinationConsequenceWhat to do
Azathioprine or 6-mercaptopurineMesalazine can inhibit their breakdown; the risk of a fall in white blood cells risesThe combination is nevertheless usual and sensible — it calls for closer blood count checks
NSAIDs such as ibuprofen or diclofenacThey can encourage flares and put an extra strain on the kidneysFor pain, discuss paracetamol in preference; see painkillers compared
Coumarin anticoagulants such as phenprocoumonThe anticoagulant effect can be influencedCheck the INR more closely, see living with blood thinners
AlcoholNo direct interaction, but it can make bowel complaints worseFind out for yourself what you tolerate, see medications and alcohol
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The point that matters most in practice is the second one: NSAIDs are available over the counter and are taken as a matter of course for headache, back pain or period pain — but in inflammatory bowel disease they count as a possible trigger of a flare. A single tablet is therefore not forbidden, but regular use needs to be discussed. Check new combinations in the interactions guide or in the interaction check in the brite app.

9. Mesalazine in Crohn's disease: an honest assessment

Ulcerative colitis and Crohn's disease are often mentioned in the same breath. When it comes to medication, though, their paths part clearly — and with mesalazine particularly clearly.

In ulcerative colitis mesalazine is the basic treatment, with good evidence. In Crohn's disease the evidence is markedly weaker: current guidelines as a rule see no relevant place for it there — neither in a flare nor for preventing relapses.⁴ The difference is anatomical: ulcerative colitis affects only the superficial lining of the large bowel, where a locally acting preparation arrives well; Crohn's disease goes into the depth of the bowel wall and can affect the whole digestive tract.

Why some people with Crohn's disease take mesalazine anyway. Often the prescription dates from a time when the diagnosis was not yet clear. That is no mistake, but it is a good occasion for the question: "what is this preparation still doing for me?" How to prepare questions like that is set out under preparing for a doctor's appointment.

10. Cortisone is for the flare, not for the long run

A severe flare often needs more than mesalazine. That is when cortisone comes into play — locally acting as budesonide or systemically as prednisolone. Both work quickly and reliably, and both are expressly not a long-term solution.

The reason: cortisone fights the inflammation but does not prevent a new flare — and the longer it is used, the higher the familiar risks such as osteoporosis, raised blood sugar and susceptibility to infection. So the rule in the guidelines is: cortisone for a limited time for the flare, mesalazine permanently for maintenance.²

Steroid dependence is a defined state, not a personal failure. If the complaints come back every time the cortisone is reduced, or if several courses are needed within a year, that counts as a sign that the basic treatment is not sufficient. The right step is then not the next round of cortisone but stepping up the long-term treatment. And never stop cortisone abruptly — why is explained in the guide stopping cortisone, with the basics in the cortisone guide.

If mesalazine is not enough for maintenance, further steps follow: immunosuppressants such as azathioprine, then biologics or modern small-molecule drugs. Mesalazine is either continued or ended alongside them, depending on the constellation — a medical decision, not one for you to make on your own.

11. Special situations: pregnancy, children, travel, diet

Pregnancy and breastfeeding. Mesalazine is among the best studied drugs used in inflammatory bowel disease in pregnancy and is regarded as suitable on current knowledge. What matters is getting the perspective right: the main risk is not the medicine but the active flare — stopping it "to be on the safe side" is therefore usually the worse choice. Orientation is offered by the guide medications during pregnancy and the Embryotox database.⁵

Travel — and the question of the cold chain. A short reassurance: mesalazine as a rule needs no refrigeration; what counts is always the statement on your own pack. Suppositories, though, are sensitive to heat and can go soft — they do not belong in the car or in checked luggage. Take a generous supply in your hand luggage, together with a copy of your medication plan. Details under medications when travelling and storing medications correctly.

Diet — without the myths. On current knowledge there is no diet that cures ulcerative colitis or replaces mesalazine treatment. What does exist are individual intolerances, which look different in a flare than in a quiet phase. Blanket lists of things to avoid taken from the internet do more harm than good, because they lead to a one-sided diet — a food diary makes more sense than a catalogue of bans, more in the guide gut health. Where complaints persist although the inflammation is quiet, it is worth looking at an accompanying irritable bowel syndrome.

12. Mesalazine experiences: what patients really ask

"I have been well for two years — why should I still take this?"

Because that is precisely the proof that it is working. Maintenance therapy has no noticeable feedback: its success consists in nothing happening. If you stop it, you carry on feeling well at first — the relapse often only comes months later and is then no longer connected with having stopped. If you would still like to get off the preparation, that is a legitimate aim to discuss — on the basis of your findings, your calprotectin value and the course of your illness, not on your own.

"I find the suppositories unpleasant — can I take just the tablets?"

Understandable, but it is often exactly the wrong part to leave out. Where the rectum is affected, the rectal form reaches the inflamed site in a concentration no tablet achieves. Before you drop it, it is worth trying a different form: foam instead of an enema, suppositories in the evening lying down, use after a trip to the toilet. And, very practically: a short demonstration at the practice or the pharmacy changes the experience surprisingly often.

"Since I started mesalazine it has got worse — am I imagining it?"

Probably not. Two explanations come into question: either the treatment is not enough for your current disease activity — then it needs stepping up. Or it is the rare paradoxical worsening, in which mesalazine itself makes the colitis worse. Both look the same from the outside. What is decisive is the timing: say exactly when the worsening began in relation to the start of treatment or a dose increase — a documented course is worth more here than any memory.

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FAQ: Common questions about mesalazine

As a rule, yes. In ulcerative colitis, maintenance therapy in symptom-free phases is the core of the treatment: it prevents the next flare and, on current knowledge, also lowers the risk of bowel cancer. Stopping on your own while you feel well counts as the commonest avoidable reason for a relapse. A reduction is decided by the treating practice on the basis of your findings and the course of your illness.
Because mesalazine works locally and has to arrive where the inflammation is. Where the rectum is affected, suppositories reach the lining in a concentration that tablets do not achieve. In left-sided disease, enemas or foam come into question, often in addition to tablets. The combination of oral and rectal use is more effective than tablets alone in more extensive disease.
The commonest are headaches, nausea, wind and skin reactions — mostly mild. Rare but important is impaired kidney function, which causes no complaints and only shows up in blood values. Changes in the blood count are likewise rare, as are very rare inflammations of the pericardium or the pancreas. That is why regular checks are part of the treatment.
Markedly less well than in ulcerative colitis. Current guidelines as a rule see no relevant place for mesalazine in Crohn's disease, neither in a flare nor for preventing relapses. The reason lies in the anatomy: Crohn's disease goes into the depth of the bowel wall and can affect the whole digestive tract. If you are taking mesalazine for Crohn's disease, asking what it is currently doing for you is justified.
As a rule, no. Tablets, granules, suppositories and enemas are usually stored at room temperature — what counts is the statement on your own pack. Suppositories, though, are sensitive to heat and should not be left in the car or in checked luggage in summer. Take your supply in your hand luggage when you travel.
Mesalazine is among the best studied drugs used in inflammatory bowel disease in pregnancy and is regarded as suitable on current knowledge. Getting the perspective right matters: an active flare poses a greater risk for the pregnancy and the child than the treatment does. Stopping it for supposed safety is therefore as a rule not sensible — discuss your plans with your practice early.

Sources

  1. Summary of Product Characteristics (SmPC) for mesalazine (oral and rectal dosage forms, current version, available through the German medicines information system). pharmnet-bund.de
  2. S3 guideline on ulcerative colitis (German Society of Gastroenterology DGVS, AWMF reg. no. 021-009, current version) — German source. awmf.org
  3. Gesundheitsinformation.de (IQWiG): Ulcerative colitis — treatment and course. Accessed 2026 — German source. gesundheitsinformation.de
  4. S3 guideline on the diagnosis and treatment of Crohn's disease (German Society of Gastroenterology DGVS, AWMF reg. no. 021-004, current version) — German source. awmf.org
  5. Embryotox, Charité — German pharmacovigilance and advisory centre on embryonic toxicology: mesalazine in pregnancy and breastfeeding. Accessed 2026 embryotox.de
  6. gesund.bund.de: Inflammatory bowel disease. Accessed 2026 — German source. gesund.bund.de

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Medical disclaimer: This article is for general information and does not replace medical advice, diagnosis or treatment. Never stop mesalazine on your own, not even in symptom-free phases — ending maintenance therapy counts as the commonest avoidable trigger of a flare. Keep to the agreed checks of your kidney values, even when you are feeling well. With severe bloody diarrhoea, a high fever, violent abdominal pain with a rigid abdomen, a marked fall in the amount of urine you pass or acute chest pain with breathlessness, seek medical help without delay, or in an emergency call 112 (emergency services in Germany). The choice of medicine and the dose are always set individually by the treating practice. Last updated: August 2026.