5-ASAs (aminosalicylates)

Last full review: April 2023

Next review date: April 2026

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This information is for people with Colitis or Crohn’s who are taking 5-ASAs. It is also for anyone who is thinking about starting treatment with 5-ASAs. You may also hear 5-ASAs called aminosalicylates. This information can help you decide if 5-ASAs are right for you. It looks at:

How 5-ASAs work
The different types of 5-ASAs that are available
What you can expect from 5-ASAs, including the possible side effects
Stopping or changing treatment

This information might use words you have not heard before. Our page on medical words can help provide an explanation.

This information is about 5-ASAs in general. It should not replace advice from your IBD team.

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Key facts about 5-ASAs
5-ASAs, also known as aminosalicylates, are an initial treatment for people with Colitis. They are sometimes used to help manage mild forms of Crohn’s, but this is less common.

You can take 5-ASAs by mouth as a tablet or capsule, or as granules that you put on your tongue and swallow with water. You can also take them by inserting a suppository or enema into your bottom.

5-ASAs work by helping to reduce inflammation in the bowel. This allows damaged tissue to heal.

5-ASAs aim to get symptoms under control and keep them under control.
Other names for this medicine
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.
How 5-ASAs work

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.
Why you might be offered 5-ASAs
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.
“”

Pentasa, alongside Humira, has really helped me get into remission and stay there after a long time of my symptoms being out of control.

Emily
Living with Colitis
Deciding which medicine to take
There are lots of things to think about when you start a new treatment. Your IBD team will discuss your options with you. When thinking about a new treatment you might want to consider the potential benefits, possible risks and the goals of your treatment. Some things to think about include:

How you will take it

How well it works

How quickly it is likely to work

Side effects you might experience

Whether you need ongoing tests or checks

Other medicines you are taking

Our Appointment guide has a list of questions you might want to ask. It can help you focus on what matters most to you. You might find our information about other medicines and surgery for Colitis helpful.
Medicine Tool

Use this tool to understand more about potential treatment options that suit your needs. The tool is designed to help you:

Understand the differences between types of medicines

Explore different treatment options based on your personal preferences

Feel empowered to discuss medicine options with your IBD team

Use our Medicine Tool
Does it matter which type of 5-ASA I have?

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.
How well do 5-ASAs work?

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.
How long do 5-ASAs take to work?

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.
How to take 5-ASAs
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.

Tablets and capsules

Many brands of 5-ASAs have a special coating around the tablets. This allows the medicine to release in the right part of the gut. It is important to not chew, cut or crush the tablets, as this could destroy the coating. This could stop the medicine releasing in the right area of your gut. You can cut, but not crush, some brands of tablet such as Pentasa. Always check the leaflet which comes with your medicine.

Granules

You take granules by placing them on your tongue and swallowing with plenty of water. If you find granules difficult to swallow with water, try swallowing them with soft food such as yoghurt. You do not need to chew granules. They are a good option for people who cannot swallow tablets or capsules easily.

Suppositories and enemas

Rectal 5-ASAs, which you insert into your bottom, can treat the lower parts of your large bowel. These areas are harder to treat with oral medicines.

Suppositories are small, waxy, bullet-shaped capsules that you insert into your bottom yourself. They dissolve at body temperature. Suppositories often work well because they can target the affected area straight away. They are also less likely to cause side effects.

Enemas come in different forms including liquid or foam. You insert them into the rectum through your bottom, using an applicator.

Foam enemas are often easier to use than liquid enemas, especially if your gut is very sensitive. Liquid enemas can usually travel further along your colon. This helps the medicine reach more of the inflammation.

Using suppositories and enemas is not usually painful. But some people may find them uncomfortable. It’s normal to find them difficult to use at first, especially if you have never used them before. But try to stick with your medicine and keep trying. Talk to your IBD team if you’re struggling to use suppositories or enemas. They will be able to support you.
“”

At first, the suppositories were very difficult to use as it felt uncomfortable and embarrassing to me, but after a while, I found that it became just another part of my bedtime routine. I find that taking Pentasa granules also helps as they can be swallowed quickly.

Emily
Living with Colitis
What is the normal dosage?
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.
How long to take 5-ASAs for

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.
Other treatments

There are different types of 5-ASAs, which come in different forms. If one does not work well, you may be able to try a different type or form, either on its own or in combination.

If 5-ASAs are not suitable for you, or you have severe side effects, your doctor may prescribe steroids. They can help you manage flare-ups. These may take a few weeks to start working and you may experience side effects from them too. Talk to your IBD team about whether they are suitable for you.

Other common treatments for Crohn’s and Colitis include immunosuppressants such as azathioprine, mercaptopurine or methotrexate. Or your doctor may offer you biologic medicines (such as adalimumab, golimumab, infliximab, ustekinumab and vedolizumab). If you have Colitis, JAK inhibitors (such as filgotinib or tofacitinib) may be an option.
Stopping or changing treatment
There are a few reasons why you or your IBD team might think about stopping or changing your treatment.

Your medicine is not working for you
If your condition has not improved within 4 weeks of starting treatment. Your IBD team might suggest stopping 5-ASAs sooner if the treatment is not working at all.

You have side effects
If you have side effects that are serious or difficult to manage, stopping 5-ASAs might be the best option.

Always talk to your IBD team if you are thinking about stopping or changing your treatment. They will be able to talk to you about what options are available.
Checks before starting treatment

You will usually need some tests to check if 5-ASAs are suitable for you. Before starting treatment, your IBD team should test your blood and pee. These tests are to check your blood and to see how well your kidneys, and liver are working.
Ongoing checks

You will usually have regular blood and pee tests while on 5-ASA treatment. This is to check for any side effects and monitor how well your medicine is working.

Your doctor may suggest having a blood test after 3 months of starting treatment, then once or twice a year after that. This is to make sure that your kidneys are still working properly. If you are taking sulfasalazine you may need blood tests more often.
Who are 5-ASAs not suitable for
5-ASAs may not be suitable for everyone. Your doctor or nurse may not offer you 5-ASAs if any of the following applies to you:

You have very poor kidney function, including if you have ever had kidney stones

You have ever had liver disease

You have an intolerance to some sugars, including lactose

You may still be offered 5-ASAs if you have any of the above health conditions. But, your doctor may adjust the dose to suit you better. If you have any of the above health conditions, or you are not sure if 5-ASAs are suitable for you, talk to your IBD team.
Side effects
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.

Common side effects (between 1 in 10 and 1 in 100 people) include:

Joint stiffness (arthralgia)

Cough

Nausea (feeling sick) and vomiting (being sick)

Diarrhea (loose and watery poo)

Headache and dizziness

Indigestion

Decrease in white blood cells which could lead to infection (leucopenia)

Mild allergic reactions including a skin rash, itching and fever-like symptoms

Less common side effects (up to 1 in 1000 people) include:

Hair loss (alopecia)

Depression

Difficulty breathing (dyspnoea)

Painful and aching muscles (myalgia)

Sensitivity to sunlight (photosensitivity reaction)

Shortage of platelets in your blood (thrombocytopenia)

The treatment which you are taking may also have its own side effects. Read the information leaflet which comes with your medicine or talk to your doctor.

Rarely, 5-ASAs can cause problems with your kidneys, liver, lungs and pancreas.
Call 999 or emergency medical help if you develop:

Chest pain or rapid heartbeat

Swelling of the face, lips or throat

Wheeziness or difficulty breathing

Unexplained bleeding, bruising or skin rashes

Changes in the colour or amount of urine you produce
Your doctor should talk through the risks and benefits before you start 5-ASAs. Let your doctor or IBD nurse know about any new symptoms you develop, whenever they occur.

This is not a full list of side effects. For more information see the Patient Information Leaflet provided with your medicine or visit medicines.org.uk/emc/.

“”

I have taken mesalazine for 24 years and have not felt any significant side effects throughout this time. Taking it has just become part of my daily routine.

Shirley
Living with Colitis
Taking other medicines
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.
Drink alcohol

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.
Vaccinations

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.
Fertility
Most 5-ASAs do not affect fertility. However, there are some that may affect your chances of conceiving if you have male reproductive organs:

Sulfasalazine can reduce sperm count and sperm motility. This is reversible and usually returns to normal 2 to 3 months after you stop taking sulfasalazine.

Zintasa is made with a coating that could affect sperm motility. If you’re taking Zintasa, you may want to try a different brand of mesalazine.

5-ASAs do not seem to affect fertility in people with female reproductive organs.

If you have concerns about your fertility, or you are trying to get pregnant, speak to your IBD team. You can also read more about fertility in our information on Reproductive health.
Pregnancy and breastfeeding

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 birth and Postnatal care and breastfeeding for more details.
Who to talk to if you are worried

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.
About this information
We follow strict processes to make sure our information is based on up-to-date evidence and easy to understand.

Please email us at evidence@crohnsandcolitis.org.uk if:

You have any comments or suggestions for improvements

You would like more information about the sources of evidence we use

You would like details of any conflicts of interest

You can also write to us at Crohn’s & Colitis UK, 1 Bishop Square, Hatfield, AL10 9NE, or contact us through our Helpline: 0300 222 5700