Asacol 400 mg gastro-resistant tablets – mesalazine for ulcerative colitis and maintenance of Crohn’s disease remission

Asacol is a medicine containing the active substance mesalazine (5-aminosalicylic acid), an intestinal anti-inflammatory agent. Its gastro-resistant coating protects the tablet in the stomach, so mesalazine is released in the intestine, where it reduces inflammation of the lining locally.

In Serbia it is authorised as 400 mg gastro-resistant tablets in packs of 100 and is available on prescription. It is used in ulcerative colitis and to maintain remission of Crohn’s disease achieved by surgery.

What is Asacol (mesalazine) used for and how is it taken?

Key facts about the medicine

What is Asacol used for?

According to the Summary of Product Characteristics, Asacol is indicated for:

• treatment of mild to moderate acute ulcerative colitis and maintenance of remission of ulcerative colitis
• maintenance of surgically induced remission of Crohn’s disease

How is it taken and dosed?

Swallow the tablets whole with enough water before food; do not chew, break or crush them. Elderly patients take the adult dose unless they have severe liver or kidney impairment. Maintenance of Crohn’s remission is not routinely recommended in children. This is the general dosage from the Summary of Product Characteristics – your doctor decides on your treatment.

Special patient groups

• Kidney impairment: use is not recommended; contraindicated in severe impairment, and stopped immediately if kidney function worsens during treatment.
• Liver impairment: caution is needed; contraindicated in severe impairment.
• Elderly: caution; prescribed only with preserved or mildly to moderately impaired liver and kidney function.
• People with asthma or lung disease, gastric or duodenal ulcer, or previous intolerance of sulfasalazine: careful supervision.

Contraindications – when the medicine must not be used

• hypersensitivity to mesalazine, salicylates or any of the excipients
• severe kidney impairment (GFR below 30 mL/min/1.73 m²)
• severe liver impairment
• children under 2 years

Warnings and precautions

• Blood tests (blood count, ALT, AST, creatinine) and urine tests before and during treatment – recommended 14 days after starting, then every 4 weeks for the next 12 weeks, and every 3 months thereafter if normal.
• Kidney stones have been reported – drink enough fluids during treatment.
• Severe skin reactions (DRESS, Stevens-Johnson syndrome, TEN) – stop at the first signs of rash or mucosal lesions.
• Serious blood disorders are very rare – with unexplained bleeding, bruising, anaemia, fever or sore throat stop the medicine immediately and contact a doctor.
• Myocarditis or pericarditis is rare; after such a reaction to mesalazine the medicine must not be restarted.
• Whole tablets or empty tablet shells may sometimes be seen in the stool; if this happens often, consult your doctor.
• Contains lactose monohydrate – people with rare hereditary galactose intolerance, lactase deficiency or glucose-galactose malabsorption must not take it.
• Urine may turn red-brown on contact with sodium hypochlorite bleach.

Interactions with other medicines, alcohol and food

• Azathioprine, 6-mercaptopurine, thioguanine – possible increased bone marrow suppression and risk of serious infections; regular blood counts are needed (weekly at the start).
• Warfarin – weak evidence that mesalazine may reduce its anticoagulant effect.
• Take the tablets before food, whole, with enough water.

Pregnancy and breast-feeding

Limited data in pregnant women do not indicate harmful effects, but one isolated case of kidney failure in a newborn after long-term high doses of mesalazine (2–4 g) has been reported. Asacol is used in pregnancy and breast-feeding only when the benefit outweighs the risk; if the baby develops diarrhoea, breast-feeding should be stopped. No effects on fertility have been observed.

Driving and using machines

Asacol has no or negligible influence on the ability to drive and use machines.

Possible side effects

• Common: rash, indigestion.
• Uncommon: fever, raised eosinophil count, tingling and pins and needles, itching, hives, chest pain.
• Rare: headache, dizziness, inflammation of the heart (chest pain, palpitations), diarrhoea, abdominal pain, wind, nausea and vomiting, increased sensitivity of the skin to light.
• Very rare: marked reduction in blood cells, allergic reactions, drug fever, lupus-like syndrome, pancolitis, nerve damage, lung disease (breathlessness, cough), pancreatitis, hepatitis, muscle and joint pain, hair loss, kidney damage, reversible reduced sperm production.
• Frequency not known: pleurisy, kidney stones, mesalazine intolerance with worsening of the disease, weight loss.

Report suspected side effects to your doctor, pharmacist or ALIMS.

Overdose, missed dose and stopping treatment

• If you have taken more than prescribed, contact your doctor immediately. Rare overdose data do not indicate kidney or liver toxicity; there is no specific antidote.
• If you forget a dose, take the next one as scheduled; do not take a double dose.
• Do not stop the medicine yourself, even if you feel better.

Related information

For additional care and support with digestive and bowel complaints, see also the Digestive system category – products in this category do not replace the medicine you have been prescribed.

Composition, packaging and manufacturer

• Active substance: mesalazine 400 mg per gastro-resistant tablet.
• Excipients – core: lactose monohydrate; sodium starch glycolate (type A); magnesium stearate; talc; povidone K25. Coating: methacrylic acid–methyl methacrylate copolymer (1:2), talc, triethyl citrate, yellow and red iron oxide (E172), macrogol 6000.
• Pack: Al/PVC blister of 10 tablets; carton with 10 blisters (100 gastro-resistant tablets).
• Marketing authorisation holder: PONTUS PHARMA D.O.O. BEOGRAD, Obilićev venac 15, Belgrade – Stari Grad.
• Manufacturer: Tillotts Pharma GmbH, Rheinfelden, Germany.

Storage

• Store below 25 °C in the original package to protect from moisture.
• Do not use after the expiry date stated on the outer pack.
• Keep out of the sight and reach of children.
• Return unused medicine to a pharmacy that collects unused medicines.

Frequently asked questions

May I halve an Asacol tablet?

No. The tablets are swallowed whole with enough water before food – they must not be chewed, broken or crushed, because the coating allows mesalazine to be released only in the gut.

Why do I see tablets in my stool?

Cases of whole tablets in the stool have been reported; sometimes it is only the empty shell. If this happens often, consult your doctor.

How often are tests needed during treatment?

Recommended 14 days after starting, then every 4 weeks for 12 weeks, and every 3 months thereafter if results are normal – or immediately if new symptoms appear.

What if I forget a dose?

Take the next dose as scheduled and do not take a double dose.

Can children use Asacol?

In children from 6 years with ulcerative colitis the dose is based on body weight; data are limited. The medicine is contraindicated in children under 2 years.

Sources

• ALIMS – Summary of Product Characteristics, Asacol® 400 mg gastro-resistant tablets (Serbian)
• ALIMS – Patient Information Leaflet, Asacol® 400 mg gastro-resistant tablets, April 2023 (Serbian)

Sources checked on: 23 October 2026.