You may also hear 5-ASAs called aminosalicylates.

There are four different 5-ASAs available:

• Mesalazine
• Olsalazine
• Balsazide
• Sulfasalazine

Remember that medicines often have two names – a scientific name and a brand name. If you are not sure about which medicine you have, ask someone from your IBD team to explain. Some 5-ASAs also come in different forms (formulations). Each one targets a different part of your gut.

Mesalazine (brand names include Asacol, Zintasa, Octasa, Pentasa, Salofalk and Mezavant)

• Asacol, Zintasa, Octasa and Salofalk are available as tablets and granules, which you take by mouth. These have a special covering known as an enteric coating. This coating dissolves at a certain level of acidity (pH) in your gut.
• Octasa is also available as suppositories and Salofalk as suppositories or enemas. You insert these into your bottom.
• Pentasa tablets and granules, which you take by mouth, work throughout your entire gut. 
• Mezavant tablets, which you take by mouth, release as they pass through your colon.

Olsalazine (brand name Dipentum)

Olsalazine comes in the form of a tablet or capsule, which you swallow with water. The medicine releases in your colon.

Balsalazide (brand name Colazide)

Balsalazide comes as a capsule which you swallow with water. The medicine releases in your colon.

Sulfasalazine (brand name Salazopyrin)

Sulfasalazine comes in the form of a tablet or liquid which you swallow with water. You can also have suppositories which you insert in your bottom.

When your symptoms get worse, known as a flare-up, your gut wall can become inflamed and irritated. 5-ASAs reduce inflammation in your bowel. Reducing inflammation allows damaged tissue in your bowel to heal and repair itself. This will help to reduce symptoms caused during a flare-up.

If you have Colitis your IBD team might suggest a 5-ASA:

• As an initial treatment for people who have mild to moderate flare-ups of Colitis.
• To maintain a period of recovery (remission) and help prevent flare-ups of Colitis in the longer term.

If you have Crohn’s, 5-ASAs are not commonly prescribed. Your IBD team may suggest a 5-ASA:

• To get your symptoms under control (induce remission) if your Crohn’s is mild and you cannot have, or decide not to have, steroids.
• If it is not clear whether you have Crohn’s or Colitis.
• To help maintain remission if you have had surgery for Crohn’s.

If you are not sure if 5-ASAs are suitable for you, talk to your IBD team. They will be able to talk you through your options and help you decide.

All 5-ASAs work in slightly different ways, including the parts of the gut that they target. Your doctor may suggest a certain type or brand of 5-ASA, depending on where you have inflammation.

If you find a type or brand of 5-ASA which works well for you, you may keep taking it long-term. If your condition changes or you start experiencing symptoms, talk to your IBD team. You may need to switch your treatment.

Sometimes, there may be supply issues with certain brands. This may mean you have to switch to a different treatment or brand. If this happens, your IBD team will talk to you about the different options available.

Write down any symptoms you have and always tell your IBD team about them. This is particularly important if you have recently switched to a new treatment.

At first, the aim of treatment is to reduce the inflammation in your gut and get your symptoms under control (remission). This is called induction treatment. Once your symptoms are under control, treatment aims to keep it under control. This is called maintenance treatment.

Find out more about how we talk about the effectiveness of medicines.

Colitis

5-ASAs work well at getting and keeping symptoms under control in people with Colitis. But they do not always work for everyone – what is right for one person, may not be right for someone else.

Getting Colitis under control

A review of studies looked at how well 5-ASAs can get symptoms of Colitis into remission. The review combined data from studies that compared 5-ASAs with a dummy treatment (placebo). The 5-ASAs in these studies were given by mouth. The review found that 5-ASAs worked better than placebo to get Colitis under control.

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After 6 to 12 weeks, more people had their Colitis under control (in remission) after taking a 5-ASA compared with people who had not been taking a 5-ASA (placebo). About 29% (29 in every 100 people) who took a 5-ASA had their Colitis in remission compared with 17% (17 in every 100 people) who took placebo.

Keeping Colitis under control

Two reviews have looked at how well 5-ASAs keep symptoms under control in people with Colitis. These reviews combined data from studies that compared 5-ASAs with a dummy treatment (placebo). One looked at rectal 5-ASAs, which you insert into your bottom. The other looked at oral 5-ASAs, which you take by mouth. The reviews found that 5-ASAs worked better than placebo to keep Colitis under control.

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After 1 year, more people had their Colitis in remission after taking a rectal 5-ASA compared with people who had been taking placebo. About 62% (62 in every 100 people) who took a rectal 5-ASA had their Colitis in remission compared with 30% (30 in every 100 people) who took placebo.

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After 6 to 12 months, more people had their Colitis in remission after taking an oral 5-ASA compared with people who had been taking placebo. About 63% (63 in every 100 people) who took an oral 5-ASA had their Colitis in remission compared with 42% (42 in every 100 people) who took placebo.

Crohn’s

Getting Crohn’s under control

A review of studies looked at how well 5-ASAs can get symptoms of Crohn’s into remission. The review combined data from studies that compared 5-ASAs with a dummy treatment (placebo). It found that sulfasalazine provides a small benefit for people with mild to moderate Crohn’s. But sulfasalazine did not work as well as steroids. Mesalazine was not effective for inducing remission in active Crohn's.

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After 17 to 18 weeks, more people had their Crohn’s in remission after taking sulfasalazine compared with people who had been taking placebo. About 45% (45 in every 100 people) who took sulfasalazine had their Crohn’s in remission compared with 29% (29 in every 100 people) who took placebo.

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After 18 weeks, more people had their Crohn’s in remission after taking a steroid compared with people who had been taking sulfasalazine. About 60% (60 in every 100 people) who took a steroid had their Crohn’s in remission compared with 41% (41 in every 100 people) who took sulfasalazine.

Keeping Crohn’s under control

Medically-induced remission

A review looked at how well 5-ASAs keep symptoms under control in people with Crohn’s who had received medicines to get their symptoms under control (in remission). This review combined data from studies that compared 5-ASAs with a dummy treatment (placebo). It found that 5-ASAs were no more effective than placebo for maintaining remission achieved by medical treatment.

Surgically-induced remission

Some people with Crohn's will need surgery to get them into remission. A review looked at how well 5-ASAs keep symptoms under control in people with Crohn’s who had surgery to induce remission. This review combined data from studies that compared 5-ASAs with a dummy treatment (placebo). It found that 5-ASAs were slightly more effective than placebo for maintaining remission in people with Crohn’s.

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After up to 5 years of treatment, slightly more people continued to be in remission after taking a 5-ASA compared with people who had been taking placebo. About 64% (64 in every 100 people) who took a 5-ASA continued to be in remission compared with 57% (57 in every 100 people) who took placebo.

Everyone responds differently to a new medicine. For most people, 5-ASAs take up to four weeks to start working.

Some types of 5-ASAs, such as sulfasalazine, should take only a few days to start working.

You’ll usually keep taking 5-ASAs for as long as they are working well.

5-ASAs come in different forms, including:

• Tablets and capsules
• Granules
• Suppositories and enemas

Which type of 5-ASA you have, and the dose, depends on how much of your gut is affected by your Crohn’s or Colitis.

You may have one form of 5-ASA at a time, or a combination, depending on your situation. Some people find that using an oral medicine, combined with a rectal treatment, works well for them. There is research which shows that using a combination of 5-ASAs, is better than using one on its own.

Your doctor may suggest that you try different combinations of 5-ASAs until you find something that works well for you.

Your doctor will decide which dose you need. It usually depends on which brand of 5-ASA you are taking, as well as how active your condition is. The dose may increase or decrease depending on how you respond. Your IBD team may also change your dose if your condition changes over time.

Unless otherwise instructed by your doctor, typical doses to treat a flare-up are:

• Granules: 1 to 2 sachets of granules (1 to 4g depending on the brand) a day, preferably in the morning. 
• Enemas: 1 to 2 enemas (1 to 2g each depending on the brand) a day. 
• Suppositories: 1 or 2 suppositories (0.5 to 1.0 g each depending on the brand) up to three times a day. 
• Tablets: 1.5 to 4.8g a day depending on the brand.

Oral 5-ASAs are often prescribed in two or three doses during the day. But evidence shows that taking these together, in a bigger daily dose, can work just as well. There are some once-a-day brands available. This means you would only need to take one dose each day.

During a flare-up, your dose may have to change to help you manage the symptoms. At other times, you will usually stay on a maintenance dose. This will help to keep your condition under control. This dose may be slightly lower than the dose you started with.

Check with your IBD team if you are not sure about the dose you should be taking.

If you forget to take a dose, take it as soon as you remember. If it is nearly time for your next dose, wait until then and continue as before. Do not take a double dose. See the information leaflet that comes with your medicine for more details.

You will probably take 5-ASAs long-term. This is to keep your condition under control and to reduce the risk of flare-ups. If you respond well to 5-ASAs you should be able to keep taking them for years. Taking 5-ASAs even when you are feeling well is likely to be the most effective way to prevent a flare-up.

Your IBD team may suggest that you keep taking 5-ASAs long-term, to lower your risk of getting bowel cancer. There is some evidence which shows that 5-ASAs can reduce the risk of bowel cancer in people with IBD. See our information on bowel cancer risk or talk to your IBD team if you're concerned about your risk of bowel cancer.

Find out more about long-term treatment for Crohn’s and Colitis in our information on Taking Medicines.

Like all medicines, 5-ASAs can have side effects, although not everyone will get them. If you do get side effects, they’re usually quite mild and you can manage them well.

You can usually take most other medicines safely with 5-ASAs. But always check with your IBD team, doctor or pharmacist if you are taking or plan to take any other medicines while you are taking 5-ASAs. This includes:

• any over-the-counter medicines, including aspirin
• medicines to treat pain or inflammation, such as ibuprofen, naproxen, meloxicam or diclofenac (these are not routinely recommended if you have IBD due to the risk of triggering a flare)
• any herbal, complementary or alternative remedies.

Read our information on Taking Medicines to find out more. 

Alcohol is not known to have any interaction with 5-ASAs. To keep the health risks from drinking alcohol low it is best to stay within the recommended limits.

It’s safe to have vaccinations whilst on 5-ASAs. This includes the annual flu jab and COVID-19 vaccines and boosters.

Before having a vaccine, you should check with your IBD team that it’s suitable for you. This is particularly important if you are also taking other medicines for your IBD. 

5-ASAs are mostly considered safe to take while pregnant.

However, balsalazide is not recommended during pregnancy. This is because there is not enough research to show if balsalazide is safe to take while pregnant.

If you take sulfasalazine while you are pregnant, you may need to take a regular high-dose folic acid supplement.

5-ASAs are mostly considered safe to take while breastfeeding.

If you are breastfeeding while taking 5-ASAs, your baby may experience some diarrhoea. This usually settles once you stop taking 5-ASAs. It can also improve if the baby starts bottle feeding with formula milk. You might want to discuss what’s best for you and your baby with your baby’s healthcare team.

See our information on Pregnancy and breastfeeding for more details. 

Taking medicines and managing side effects can be difficult – we understand and we’re here to help. Our Helpline can answer general questions about treatment options. It can also help you find support from others with the conditions.

Your IBD team are also there to help. You can talk to them about your dosage, how they’ll be monitoring you and what alternatives may be available. You should also get in touch with your IBD team if you have any new symptoms or side effects.

It can take time to find the medicine that’s right for you. Don’t be afraid to ask questions and seek out extra support when you need it.

This information is general and doesn’t replace specific advice from your health professional. Talk to your doctor or IBD team for more information.