Sounds like 'ohl-SAL-uh-zeen'

Olsalazine is used to treat ulcerative colitis. Find out how to take it safely and possible side effects. Olsalazine is also called Dipentum.

Type of medicine

Also called

  • Belongs to a group of medicines called aminosalicylates

  • Dipentum®

What is olsalazine?

Olsalazine is used to treat certain bowel conditions such as ulcerative colitis. It works by reducing inflammation in the gut and may decrease symptoms such as pain and diarrhoea. It allows the damaged gut to heal and helps to prevent symptoms from flaring up again. Read more about ulcerative colitis

In New Zealand olsalazine is available as tablets (500 mg) and capsules (250 mg). 


  • The usual dose of olsalazine is 500 mg two times a day. 
  • Your doctor will start you on a low dose and will increase it over the first few days. You will be given higher doses during 'flare-ups', and your dose will reduce again when your symptoms improve.
  • Always take your olsalazine exactly as your doctor has told you. The pharmacy label on your medicine will tell you how much olsalazine to take, how often to take it and any special instructions.

How to take olsalazine

  • Take your olsalazine with a drink of water and food. Taking olsalazine with or soon after food helps to reduce side-effects, such as diarrhoea and stomach upset.
  • Take your olsalazine dose at the same times each day, usually in the morning and the evening. 
  • If you forget to take your dose, take it as soon as you remember that day. But, if it is nearly time for your next dose, just take the next dose at the right time. Do not take double the dose.
  • Olsalazine will start working straight away but it may take a week or so for your symptoms to improve. It will take a few months for the symptoms to go away completely, as it takes time for the gut to heal.

Possible side effects

Like all medicines, olsalazine can cause side effects, but not everyone gets them. Often side effects improve as your body gets used to the new medicine. You will need to have blood tests to make sure it is not affecting your blood or kidneys.

Side effects What should I do?
  • Diarrhoea (runny poos)
  • Tummy pain
  • Feeling sick (nausea) or being sick (vomiting)
  • These are quite common when you first start taking olsalazine, and usually go away with time.
  • Take your olsalazine with food. 
  • Tell your doctor if troublesome.
  • Signs of problems with your blood cells such as bruising or bleeding easily, ongoing sore throat, mouth ulcers, dizziness and feeling tired and fever.
  • Tell your doctor immediately or ring HealthLine 0800 611 116
  • Signs of an allergic reaction such as skin rash, itching, blisters, peeling skin, swelling of the face, lips, mouth or have problems breathing
  • Tell your doctor immediately or ring HealthLine 0800 611 116


When certain medications are taken together, an unintended reaction may occur – this is known as an interaction. Olsalazine may interact with a few medications and herbal supplements, so check with your doctor or pharmacist.

Learn more

If you have any questions about your medicines or about the combination of medicines that you are on, or if you are concerned about any side effects or interactions, please talk to your pharmacist or doctor.

The following links provide further information on olsalazine. Be aware that websites from other countries may contain information that differs from New Zealand recommendations.

Dipentum Medsafe Consumer Information Sheet (NZ)
Olsalazine Patient Info, UK

Credits: Sandra Ponen, Pharmacist. Reviewed By: Angela Lambie, Pharmacist, Auckland Last reviewed: 20 Oct 2016