Patient Leaflet Updated 28-Jul-2025 | Ferring Pharmaceuticals Ltd
Pentasa Slow Release Tablets 500mg & 1g
PENTASA®
Slow Release Tablets 500mg
Slow Release Tablets 1g
Mesalazine
1. What Pentasa Tablet is and what it is used for
2. What you need to know before you take Pentasa Tablets
3. How to take Pentasa Tablets
4. Possible side effects
5. How to store Pentasa Tablets
6. Contents of the pack and other information
Each Pentasa Slow Release Tablet contains mesalazine 500mg or 1g as the active ingredient. Mesalazine belongs to a group of medicines called salicylates.
Pentasa Tablets are used for the treatment of mild to moderate attacks of ulcerative colitis and to help maintain freedom from further attacks. Ulcerative colitis is an inflammatory bowel disease in which the lining of the intestine becomes inflamed and develops many tiny breaks in its surface (ulcers) which may bleed.
Pentasa tablets release the active ingredient slowly which then acts locally to reduce the inflammation and help relieve or stop the pain.
Talk to your doctor or pharmacist before taking Pentasa Tablets if you:
Mesalazine may produce red-brown urine discoloration after contact with sodium hypochlorite bleach in the toilet water. It concerns a chemical reaction between mesalazine and bleach and is harmless.
Serious skin reactions including Drug reaction with eosinophilia and systemic symptoms (DRESS), Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) have been reported in association with mesalazine treatment. Stop using Pentasa tablets and seek medical attention immediately if you notice any of the symptoms related to these serious skin reactions described in section 4.
If you experience strong or recurrent headache, disturbed vision, or ringing or buzzing in the ears contact your doctor immediately.
While you are on treatment with this medicine, your doctor will normally arrange blood and urine tests to check your kidney function especially at the beginning of treatment.
You should make sure that you don’t become dehydrated, while you are taking this medicine. This can occur after severe or prolonged attacks of vomiting and/or diarrhoea, high fever or heavy sweating. If this occurs, you should talk to your doctor or a pharmacist for advice as soon as possible.
Tell your doctor or pharmacist if you are taking or have recently taken any other medicines, including medicines obtained without a prescription. This is especially important if you are taking any of the following :
If you are pregnant or breast-feeding, think you may be pregnant or are planning to have a baby, ask your doctor or pharmacist for advice before taking this medicine.
There is limited experience with the use of mesalazine during pregnancy and breast-feeding. Blood disorders have been reported in newborns of mothers being treated with this medicine. The newborn may develop allergic reactions after breast-feeding, e.g. diarrhoea. If the newborn develops diarrhoea, breast-feeding should be discontinued.
This medicine is not known to affect the ability to drive and/or use machines.
Always take Pentasa exactly as your doctor has told you.
You should check with your doctor or pharmacist if you are not sure.
Adults
To treat an attack of colitis, your doctor will usually prescribe a dose of up to 4g mesalazine a day to be taken as eight 500mg tablets or four 1g tablets, once a day or in two or three divided doses.
To help maintain freedom from further attacks, your doctor will usually prescribe a dose of 2g mesalazine a day, to be taken as four 500mg tablets or two 1g tablets, once a day.
Children 6 years of age and older:
The dose for children will be calculated by your doctor and depends on the child’s weight. It is generally recommended that half the adult dose is given to children up to 40 kg of body weight and the normal adult dose to children above 40 kg of body weight.
You should take the tablets orally (by mouth) either whole or broken up, they should not be crushed or chewed. If you have difficulty swallowing the tablets you can disperse them in a small quantity of cold water (approximately 50ml) then stir and drink immediately.
If you have accidentally taken too many tablets, you should go to your nearest emergency department or contact your doctor immediately. Take the pack and any remaining tablets with you.
If you forget to take a dose, then take it as soon as you remember, unless it is less than 3 hours until your next dose. Do not take a double dose to make up for the forgotten one.
If you have any further questions on the use of this product, ask your doctor or pharmacist.
Like all medicines, Pentasa can cause side effects, although not everyone gets them.
If you experience any of the above side effects, you should contact your doctor or go to the nearest hospital emergency department immediately.
The following common side effects may affect up to 1 in 10 people:
The following rare side effects may affect up to 1 in 1,000 people:
The following very rare side effects may affect up to 1 in 10,000 people:
Not known (frequency cannot be estimated from the available data)
If you get any side effects, talk to your doctor or pharmacist. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the Yellow Card Scheme, website: www.mhra.gov.uk/ yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store. By reporting side effects, you can help provide more information on the safety of this medicine.
Keep this medicine out of the sight and reach of children.
Do not use this medicine after the expiry date which is stated on the carton and blister. The expiry date refers to the last day of that month.
Do not store above 25ºC. Do not freeze.
Store in original packaging to protect from light.
Do not throw away any medicines via wastewater or household waste. Ask your pharmacist how to throw away medicines you no longer use. These measures will help protect the environment.
The active substance is mesalazine
Each tablet contains 500mg or 1g of mesalazine.
Other ingredients: povidone, ethylcellulose, microcrystalline cellulose, magnesium stearate and talc.
Pentasa Tablets 500mg
White/grey to pale brown, specked round tablets, scored and marked ‘500mg’ on one side and ‘PENTASA’ on the other side. Each carton contains 100 tablets presented in blister strips of 10 tablets per strip.
Pentasa Tablets 1g
White/grey to pale brown, specked oval tablets, marked with ‘PENTASA’ on both sides. Each carton contains 60 tablets presented in blister strips of 10 tablets per strip.
This leaflet was last revised in May 2025.
PENTASA is a registered trademark.
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+44 (0)844 931 0051
http://www.ferring.co.uk
+44 (0)844 931 0050
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