Mesalazine

What is mesalazine?

Mesalazine (also known as mesalamine or 5-aminosalicylic acid/5-ASA) is a prescription-only anti-inflammatory medicine used to treat inflammatory bowel diseases. It belongs to a group of drugs called aminosalicylates. Mesalazine is available under various brand names, including Asacol, Pentasa, Mezavant, Octasa, Salofalk, and Zintasa[1]. 

What is mesalazine used for?

Mesalazine is mainly used to manage two types of inflammatory bowel disease[1]: 

• Ulcerative colitis – to treat flare-ups and to help keep the condition in remission 

• Crohn's disease (specifically mild ileo-colitis), primarily for maintaining remission; it is not typically used for treating active flare-ups. 

How does mesalazine work?

Mesalazine acts directly on the lining of the gut to reduce inflammation. It works by blocking the production of chemical messengers like prostaglandins and leukotrienes, which are involved in inflammation and tissue damage in the bowel[1]. 

Who can take mesalazine?

Mesalazine is suitable for many people with inflammatory bowel disease. You can take mesalazine if you[1]: 

• Have ulcerative colitis or Crohn’s ileo-colitis 

• Most adults and children aged 5 years and older 

However, you should not take mesalazine if you: 

• Are allergic to mesalazine, aspirin or other salicylates 

• Have serious liver or kidney disease 

• Have a history of blood disorders or serious skin reactions after using mesalazine 

• Please tell your doctor or pharmacist about any conditions you may have or medication you take before you start treatment, and always follow the instructions in the Patient Information Leaflet[2].  

What is the typical dosage of mesalazine?

Your mesalazine dose depends on what it is for, which brand you’re using, and if you’re taking it for a short or long time. Once your symptoms improve, your dose will likely be reduced, sometimes called a maintenance dose. If your symptoms return, your dose may be increased again[1]. 

A child's dose may be lower and is usually prescribed by doctors based on their weight. Always follow the instructions given by your doctor and the patient information leaflet. 

How do you take mesalazine?

Mesalazine comes in different forms, and the way you take it depends on the preparation[1]: 

• Tablets or granules should be swallowed whole with water – do not crush or chew 

• Suppositories, rectal foam, or enemas should be used exactly as directed 

• It’s best to take mesalazine with or after food to reduce the risk of stomach upset 

• Drink plenty of fluids throughout the day to help prevent kidney stones 

Can you stop taking mesalazine?

Do not stop taking mesalazine without medical advice. Stopping treatment suddenly may lead to a flare-up of symptoms or worsening of your condition[1]. 

What do you do if you take too much mesalazine?

If you take more mesalazine than prescribed[1]: 

• Contact your doctor, pharmacist or go to A&E straight away 

• Take the medication packaging with you 

• Symptoms of overdose may include nausea, vomiting, stomach pain, or drowsiness 

What do you do if you forget to take mesalazine?

If you miss a dose, take it as soon as you remember. If it’s nearly time for your next dose, skip the missed dose. Do not take two doses at once to make up for a missed one[1]. 

What medicines can’t you take with mesalazine?

Mesalazine can interact with certain medications. You should tell your doctor if you are taking[1]: 

• NSAIDs such as ibuprofen or aspirin 

• immunosuppressants that may affect kidney function, such as azathioprine, 6-mercaptopurine, or thioguanine 

• Laxatives, like lactulose, for constipation 

• Blood thinners such as warfarin 

Always inform your doctor or pharmacist about all medications and supplements you take before you start a new medicine, and follow the instructions in the Patient Information Leaflet[2]. 

What are the side effects of mesalazine?

Most people tolerate mesalazine well, but side effects can occur. The most common side effects include[1]: 

• Headache 

• Nausea 

• Stomach pain 

• Diarrhoea 

• Wind (flatulence) or indigestion 

Serious side effects for which you should seek urgent medical attention may include[1]: 

• Blood in your urine or changes in kidney function 

• Yellowing of the skin or eyes (possible liver problems) 

• Unexplained rash, fever, or chest pain 

• Unusual bruising or bleeding (signs of blood disorders) 

• Severe skin reactions such as Stevens-Johnson syndrome which causes flu-like symptoms and a rash of circular patches. This is more common if you have had it before, have a weakened immune system, or a close family member has had it in the past 

You should contact your GP if you experience any of these symptoms. In rare cases, the medicine may cause a serious allergic reaction (anaphylaxis). You should call 999 or visit A&E immediately if you believe this is happening[1]. 

Symptoms of anaphylaxis include[1]:  

• Difficulty breathing  

• Tightness in throat and chest  

• Swelling of the tongue or throat  

• Feeling faint or dizzy  

• Blue/grey skin or lips  

• Loss of consciousness 

If you experience any side effects, including those not listed, you are encouraged to report them via the Yellow Card Scheme or contact your doctor, pharmacist, or nurse. This information is intended as a summary for general awareness and does not replace professional medical advice. 

The information provided in the side effects section is not a comprehensive list of all possible side effects associated with this medication. For a complete list of side effects, please refer to the Patient Information Leaflet (PIL) provided with your medication or consult your healthcare professional[2]. 

Frequently asked questions about mesalazine

Can I drink alcohol while taking mesalazine? 
Yes, in moderation. However, alcohol may irritate your digestive system, so be cautious if you have a sensitive gut[1]. 

How long does mesalazine take to work? 
You may begin to notice improvement within a few days, but full effects may take a few weeks[1]. 

Can I take mesalazine long term? 
Yes, mesalazine is often used long-term to help prevent flare-ups and keep inflammatory bowel disease under control[1]. 

Is mesalazine safe during pregnancy? 
Mesalazine is generally considered safe during pregnancy but always speak to your doctor or pharmacist before starting or continuing treatment[1]. 

Can mesalazine cause weight gain? 
Weight gain is not a common side effect of mesalazine[1]. 

Can I switch brands of mesalazine? 
Only under medical supervision. Different brands release the medicine in different parts of the gut[1]. 

Does mesalazine affect fertility? 
There is no strong evidence that mesalazine affects fertility, but if you're planning a pregnancy, it’s a good idea to discuss it with your doctor[1]. 

For the official NHS guide to mesalazine, visit their website.