Aminosalicylates (5-ASAs)

Last reviewed: November 2017

Patient talking with nurse

This information contains a brief overview of aminosalicylic acids, also known as 5-ASAs, which are used to treat Crohn’s and Colitis (the two main forms of Inflammatory Bowel Disease - IBD). It's about 5-ASAs in general and is not intended to replace specific advice from your doctor or any other health professional.

For further information please talk to your doctor or specialist IBD team, or look at the information sheet supplied with your medication or from the website:

Download this information (PDF)

Read about dosage

  • Why am I being treated with this medicine?
    5-ASAs are often the first treatment option for mild to moderate flare-ups of Ulcerative Colitis. They may then be prescribed to maintain remission and help prevent flare-ups on a longer-term basis.

    5-ASAs are used less often in the management of Crohn’s Disease, but you may be given them as a first option if your condition is mild. 5-ASAs can also help manage symptoms of Crohn’s after surgery.

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

    Living with Colitis 

  • Other names for this medicine
    There are several types of 5-ASA drugs, also often referred to by their various brand names:
    • Sulphasalazine (brand names include Salazopyrin)
    • Mesalazine (brand names such as Asacol, Ipocol, Octasa, Pentasa, Salofalk and Mezavant). This 5-ASA comes in different formulations which target slightly different parts of the digestive system.
      • Asacol, Ipocol, Octasa and Salofalk tablets and granules have a special covering, known as an enteric coating, that dissolves at a certain pH (acidity) in the gut. This means that they begin their release in the last part of the small intestine and the beginning of the colon.
    • Pentasa tablets and granules work throughout the gut.
    • Mezavant tablets release their mesalazine as they pass through the large intestine (colon).
    • Olsalazine (brand name Dipentum) and balsalazide (brand name Colazide). These 5-ASAs are also released in the large intestine.
  • How does it work?
    During a flare-up of Crohn's or Colitis the bowel wall becomes inflamed. 5-ASA drugs are chemically related to aspirin and work by reducing this inflammation, allowing damaged tissue to heal.

    Knowing that 5-ASAs have been around for decades makes me feel more comfortable about their long term usage. 

    Living with Crohn's 

  • Does it matter which type of 5-ASA I have?
    As some 5-ASAs work best in certain parts of the gut, you may be prescribed a particular type or brand depending on where you have inflammation. Though all types of 5-ASAs are equally safe and effective, they have slightly different formulations. Many IBD specialists believe that if a particular brand or type of 5-ASA is working well, you should not be switched to another without a good clinical reason. Your doctor should discuss any need to switch medicines with you, giving you an opportunity to have input into the decision. If it is necessary to switch brands, it is a good idea to report any changes in symptoms to your doctor.
  • How do I take 5-ASA?
    5-ASAs can be taken orally by swallowing a tablet, capsule or granule, or topically through the anus as a suppository or an enema. The best form for you will depend on how severe your condition is and how much of your colon is affected. A combination of oral and rectal treatment is often more effective than one approach alone.

    Tablets and capsules

    Many brands of 5-ASAs have a special enteric coating around the tablets to enable the medicine to be released in the right part of the gut. It is therefore important to not chew, cut or crush the tablets, as this will destroy the coating and stop the medicine being released in the right area. A select few brands, such as Pentasa, can be cut but not crushed. Check with your doctor or read the information leaflet that comes with your medicine.

    Oral 5-ASAs are often prescribed in two or three doses during the day. However, taking these together in a single daily dose may be just as effective, and there are once-a-day brands available. If you feel this could be helpful for you, discuss this with your doctor.


    Some 5-ASAs come in granules that are placed directly on the tongue and swallowed with plenty of liquid without chewing. This can be helpful if you have difficulty swallowing tablets.

    Suppositories and enemas

    Rectal 5-ASAs are used to treat the lower parts of the colon and the rectum, which are harder to treat with oral medication.

    Suppositories are small, waxy bullet-shaped capsules of the drug that are inserted through the anus and dissolve at body temperature. Enemas can come in a liquid or foam form, and are put into the rectum through the anus using a specially designed applicator. Foam enemas are often easier to retain than liquid enemas, so they can be particularly useful at the beginning of a flare-up, when the gut is most sensitive. Liquid enemas can usually travel farther along the colon, reaching more of the inflammation.

    Taking an enema or suppository can often be quite uncomfortable in the beginning, and take a while to get used to. Don’t be discouraged if it takes a few tries before you’re able to retain the medicine. Read the patient information leaflet that comes with your medicine for instructions on how to administer the treatment, and talk to your doctor or IBD nurse if you are struggling.

    For more details about the different forms drugs come in, see our information sheet Taking Medicines.

    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.

    Living with Colitis 

  • What is the normal dosage?
    The dose you take will be decided by your doctor. It usually depends on which brand of 5-ASA you are taking, as well as how active your disease is. The dose may be increased or decreased depending on how you respond.
    Unless otherwise instructed by your doctor, typical doses to treat a flare-up are:
    • Granules: 1 - 2 sachets of granules (1 - 4g depending on the brand) a day, preferably in the morning
    • Enemas: 1 -2 enemas (1 - 2g each depending on the brand) a day Suppositories: 1-2 suppositories (0.5–1.5 g each depending on the brand) up to three times a day
    • Tablets: 1.5 – 4.8g a day depending on the brand

    You will usually remain on a maintenance dose to help keep your disease under control. This dose may be slightly lower than the dose you started with.

    It is important that you do not change your dosage without first speaking to your IBD team. In some cases, it may be possible to work out a ‘flare-up plan’ with your team, which will allow you to adjust your medication yourself.

    It is important to know the difference between your dosage for maintaining remission, and your dosage for managing a flare-up. This has given me opportunities for early intervention when I feel like I am about to become unwell.

    Living with Colitis

  • How long will it take to work?
    It can take up to three weeks after starting 5-ASAs to feel the benefits.
  • How long will I be on 5-ASAs?
    You will probably be advised to take 5-ASAs long-term to keep your condition under control and reduce the risk of flare-ups. If you respond well to 5-ASAs you should be able to keep taking them for some years. Taking 5-ASAs even when you’re feeling well is likely to be the most effective way to prevent a flare-up. Our information sheet Taking Medicines has some helpful guidance about taking drugs for your Crohn's or Colitis long-term.

    Some people with Crohn's or Colitis have a slightly increased risk of developing colon cancer, and there is some evidence that using 5-ASAs long-term can decrease this risk. If you have Colitis your doctor may advise you to continue to take a 5-ASA indefinitely. For more details see our information on Bowel Cancer and Crohn's and Colitis.

    Although nobody likes taking pills, it was good to know that I’d got something to fight back with. Swallowing a few pills every day is a minor inconvenience compared to Crohn’s.

    Living with Crohn's 

  • How effective are 5-ASAs?
    5-ASAs are an effective treatment option for Ulcerative Colitis, with seven in 10 people responding well to the medicine. While 5-ASAs may help flare-ups of mild Crohn’s Disease, there is little evidence that they are effective in maintaining remission. As there is less evidence of their effectiveness, 5-ASAs are not recommended for severe Crohn’s.
  • What checks will I need on 5-ASA?
    Before starting treatment with 5-ASAs, you will have a blood test to check your kidney function. Kidney function should then be monitored regularly during treatment.

    You will usually have regular blood tests while on 5-ASA treatment to check for any unwanted side effects. You may have a blood test after three months, then annually. If you are taking sulphasalazine you may need slightly more frequent blood tests.

  • What are the most likely side effects on 5-ASAs?
    Like all drugs, 5-ASAs can have side effects, although not everyone will get them, and some are quite rare in comparison to other IBD treatments. They can include:
    • Nausea, vomiting, and watery diarrhoea
    • Headache and indigestion
    • Mild allergic reactions with rash, itchiness and fever

    Sulphasalazine can also reduce the body’s ability to absorb folates (B vitamins) which are essential for blood cell formation. Some people taking sulphasalazine may need a folic acid supplement.

    Rarely, 5-ASAs can cause problems with the kidneys, liver, lungs and pancreas. Tell your doctor immediately 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.

    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.

    Living with Colitis

  • Vaccinations
    It is safe to have vaccinations whilst on 5-ASAs, though you should check with your doctor beforehand if you are also taking other medicines for your Crohn's or Colitis
  • Can I take other medicines along with 5-ASAs?
    Most other drugs can be taken safely, however always check with your doctor or pharmacist first. Many people will be prescribed other medication in addition to 5-ASAs to treat their Crohn's or Colitis. This is known as combined therapy. Read our information on Taking Medicines to find out more.
  • Can I drink alcohol while taking 5-ASAs?
    Alcohol is not known to have any interaction with 5-ASAs, but for general health reasons it is best to keep within the Department of Health guideline limits
  • Do 5-ASAs affect fertility?
    Sulphasalazine can cause male infertility by reducing the sperm count, but this usually resolves within two to three months once the drug is stopped. If you are trying for a baby, you may be switched to a different brand, as other 5-ASAs do not affect fertility. See our information on Reproductive health.
  • Can I take 5-ASAs while pregnant or breastfeeding?
    5-ASA drugs are mostly considered safe to take while pregnant and breastfeeding. Studies have found no increased risks of birth defects, low birth weight or similar complications in the babies of people taking 5-ASAs.

    While 5-ASAs can be taken if you are breastfeeding, small amounts do pass into breast milk. Infants of breastfeeding mothers using 5-ASA can in very rare cases develop diarrhoea due to allergic reactions, so should be carefully monitored. This resolves itself once the drug is stopped or the baby starts bottle feeding.

    If you are taking sulphasalazine while pregnant, you should also take a folic acid supplement daily, as the medicine causes folate deficiency.

    It is important to talk to your IBD team about the risks and benefits for you, so that decisions can be made based on your own individual situation.

    See our information on Pregnancy for more details.

  • Who should I talk to if I am worried?
    If you are worried about side effects, or have other questions about your 5-ASA treatment, discuss them with your specialist doctor or IBD nurse. They should be able to help you with queries such as why it has been prescribed, what the correct dose and frequency is, what monitoring is in place, what you should do if new symptoms occur, and also what alternatives may be available.
  • Help and support from Crohn's & Colitis UK
    We offer more than 50 publications on many aspects of Crohn’s DiseaseUlcerative Colitis and other forms of Inflammatory Bowel Disease. You may be interested in our comprehensive booklets on each disease, as well as the following publications:

    • Living With Crohn's or Colitis
    • Fatigue
    • Taking Medicines
    • Managing Bowel Incontinence
    • Living With a Stoma

    Health professionals can order some publications in bulk by using our online ordering system. If you would like a printed copy of a booklet or information sheet, please contact our helpline.

    Our helpline is a confidential service providing information and support to anyone affected by Crohn's or Colitis. Our team can:
    • help you understand more about Crohn's or Colitis, diagnosis and treatment options
    • provide information to help you to live well with your condition
    • help you understand and access disability benefits
    • be there to listen if you need someone to talk to
    • help you to find support from others living with the condition

    Call us on 0300 222 5700 
    Use our LiveChat 

    Crohn’s & Colitis UK Forum

    This closed-group community on Facebook is for everyone affected by Crohn's or Colitis. You can share your experiences and receive support from others.

    Crohn’s & Colitis UK Patient Panels

    IBD Patient Panels, which are supported by Crohn’s & Colitis UK, are groups of people with Crohn's or Colitis who use their perspective as a patient to work with their IBD healthcare team to help improve their hospital services. For more information on patient panels, please contact our Patient Engagement Team.

    Crohn’s & Colitis UK Local Networks

    Our Local Networks of volunteers across the UK organise events and provide opportunities to get to know other people in an informal setting, as well as to get involved with educational, awareness-raising and fundraising activities. You may find just being with other people and realising that you are not alone can be reassuring. Families and relatives may also find it useful to meet other people with Crohn's or Colitis. All events are open to members of Crohn’s & Colitis UK


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