November 28, 2023

What Is Colazal?

Colazal (balsalazide) is a prescription medication used to treat mild to moderately active ulcerative colitis in people 5 years and older.

Colazal is a derivative of 5-aminosalicyclic-acid (5-ASA), a class of drugs commonly used to treat ulcerative colitis. It works as an anti-inflammatory agent.

When taken, balsalazide is converted into mesalamine in the colon only and works to reduce bowel inflammation and improve symptoms of ulcerative colitis. Its exact mechanism of action (the way it works) in ulcerative colitis is still unclear to researchers.

Balsalazide is available as a prescription oral capsule under its brand name (Colazal) and as a generic medication.

Drug Facts

Generic Name: Balsalazide
Brand Name: Colazal
Drug Availability: Prescription
Administration Route: Oral
Therapeutic Classification: Gastrointestinal agent
Available Generically: Yes
Controlled Substance: N/A
Active Ingredient: Balsalazide disodium
Dosage Form(s): Capsule

What Is Colazal Used For?

The Food and Drug Administration (FDA) approved Colazal to treat mild to moderately active ulcerative colitis in:

  • Adults (18 and older) for up to 12 weeks
  • Children (5 to 17 years old) for up to eight weeks

Ulcerative colitis is an inflammatory bowel disease that primarily targets the colon. It can cause bloody diarrhea, abdominal pain, and an urgent need to empty the bowels. Colazal is prescribed to help improve these symptoms by reducing bowel inflammation.

How to Take Colazal

Follow these guidelines for taking Colazal:

  • Take Colazal with or without food.
  • Swallow the capsules whole; do not cut, crush, or break them.
  • If you have difficulty swallowing pills, you may open the capsule and sprinkle the contents on applesauce. You can chew the capsule contents before swallowing. Immediately consume the mixture upon preparation.
  • Do not store any of the leftover applesauce-drug mixture for future use.


Store Colazal capsules at room temperature (between 68 F and 77 F) and protect them from light.

Off-Label uses

Healthcare providers may prescribe this medication for off-label uses, meaning for conditions not specifically indicated by the FDA.

Off-label, balsalazide is sometimes used for the maintenance remission of ulcerative colitis (beyond the FDA-approved period of eight or 12 weeks of use).

How Long Does Colazal Take to Work?

In clinical trials, Colazal significantly improved ulcerative colitis symptoms in eight to 12 weeks. Some individuals saw improvements four to six weeks after starting treatment.

What Are the Side Effects of Colazal?

This is not a complete list of side effects, and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your healthcare provider or pharmacist. You may report side effects to the FDA at or 1-800-FDA-1088.

Common Side Effects

Common side effects that may occur with Colazal include:

Severe Side Effects

Contact your healthcare provider immediately if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following:

Report Side Effects

Colazal may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA’s MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Colazal Should I Take?

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The dose of this medicine will be different for different patients. Follow your doctor’s orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For treatment of ulcerative colitis:

    • For oral dosage form (capsules):

      • Adults—2.25 grams (g) (3 capsules) 3 times a day for 8 weeks. You may need to take the medicine for up to 12 weeks as ordered by your doctor.
      • Children 5 years of age and older—2.25 g (3 capsules) 3 times a day for 8 weeks or 750 milligrams (mg) (1 capsule) 3 times a day for 8 weeks.
      • Children younger than 5 years of age—Use and dose must be determined by your doctor.
    • For oral dosage form (tablets):

      • Adults—Three 1.1-gram (g) tablets 2 times a day, for a total daily dose of 6.6 g, taken for up to 8 weeks.
      • Children—Use and dose must be determined by your doctor.


Colazal has not been studied in pregnancy. However, balsalazide disodium is a prodrug (a drug that turns into an active form of the drug once in the body) that converts to mesalamine in the colon.

Published data on the use of mesalamine in pregnancy, including meta-analyses and cohort studies, have not shown an association between mesalamine and major birth defects, miscarriage, or adverse effects on the pregnant person or fetus.

It is unknown if Colazal is excreted in breast milk. However, mesalamine (the active metabolite of Colazal) is thought to have caused a few cases of diarrhea in exposed infants. Most experts generally consider mesalamine safe during breastfeeding.

The safety and efficacy of Colazal have not been established in children under 5 years old.

Missed Doses

Take a missed dose as soon as you remember. If it’s almost time for the next dose, skip the missed dose and take the next regularly scheduled dose. Do not double up to make up for the missed dose.

Overdose: What Happens If I Take Too Much Colazal?

There have been no reports of serious adverse events related to an overdose of Colazal.

An overdose of mesalamine (the active metabolite of Colazal) may result in symptoms such as:

  • Tinnitus (ringing in the ears)
  • Neurological symptoms, like headache, dizziness, confusion, and seizures
  • GI-related issues, like nausea, vomiting, abdominal pain, or diarrhea
  • Rapid breathing

Treatment would likely be supportive, with attention to correcting electrolyte imbalances. 

What Happens If I Overdose on Colazal?

If you think you or someone else may have overdosed on Colazal, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn’t breathing after taking Colazal, call 911 immediately


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It is important that your doctor check your progress at regular visits. This will allow your doctor to see if this medicine is working properly and to decide if you should continue to take it. Blood and urine tests may be needed to check for any unwanted effects.

If your symptoms do not improve or if they become worse, check with your doctor.

This medicine may cause serious kidney problems, including kidney stones. Check with your doctor right away if you have lower back or side pain, decreased frequency or amount of urine, bloody urine, increased thirst, loss of appetite, nausea, vomiting, unusual tiredness or weakness, swelling of the face, fingers, or lower legs, weight gain, or trouble breathing.

Check with your doctor right away if you have stomach pain, bloody diarrhea, cramps, fever, headache, or a rash while you are using this medicine. These may be symptoms of a condition called mesalamine-induced acute intolerance syndrome.

Call your doctor right away if you have difficulty breathing or swallowing, a fast heartbeat, itching, rash, or skin redness, or swelling of the face, throat, or tongue. These may be symptoms of an allergic reaction to this medicine.

This medicine may cause serious skin reactions, including Stevens-Johnson syndrome, toxic epidermal necrolysis, drug reaction with eosinophilia and systemic symptoms (DRESS), and acute generalized exanthematous pustulosis (AGEP). Check with your doctor right away if you have black, tarry stools, blistering, peeling, or loosening of the skin, chest pain, chills, cough, diarrhea, itching, joint or muscle pain, painful or difficult urination, red irritated eyes, red skin lesions, often with a purple center, sore throat, sores, ulcers, or white spots in the mouth or on the lips, swollen glands, trouble breathing, unusual bleeding or bruising, or unusual tiredness or weakness.

Check with your doctor right away if you have pain or tenderness in the upper stomach, pale stools, dark urine, loss of appetite, nausea, vomiting, or yellow eyes or skin. These could be symptoms of a serious liver problem.

This medicine may make you more sensitive to light and cause serious unwanted skin reaction. This is more likely if you have an existing skin problem (eg, atopic dermatitis, atopic eczema). Check with your doctor right away if you have increased sensitivity of the skin to sunlight, itching, redness or other discoloration of the skin, severe sunburn, or skin rash. Use a sunscreen when you are outdoors. Avoid sunlamps and tanning beds.

Make sure any doctor or dentist who treats you knows that you are using mesalamine. This medicine may affect the results of certain medical tests.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

What Are Reasons I Shouldn’t Take Colazal?

Do not take Colazal if you are allergic to salicylates or any components of Colazal capsules or balsalazide metabolites. Allergic reactions may include anaphylaxis (a severe, whole-body reaction), bronchospasm (narrowing of the airways), or skin reactions.

What Other Medications Interact With Colazal?

Other drugs may interact with Colazal. Before starting treatment, tell your healthcare provider all the medications you currently take, including prescription and over-the-counter (OTC) drugs, vitamins, or herbal supplements.

Colazal may interact with the following drugs:

  • Nonsteroidal anti-inflammatory drugs (NSAIDs): NSAIDs include drugs like aspirin, Advil (ibuprofen), Naprosyn (naproxen), and others. Taking Colazal and NSAIDs together can increase the risk of GI side effects, including ulcers and bleeding, and kidney-related problems.
  • Azathioprine, 6-mercaptopurine, and thioguanine: Taking these drugs with Colazal may increase the risk of blood disorders, bone marrow failure, and complications. Your healthcare provider may need to carefully monitor your blood cell and platelet counts if you must take these medications at the same time.

Other interactions may occur. Ask your healthcare provider or pharmacist for a full list of drug interactions.

What Medications Are Similar?

Sulfasalazine is another drug that can be used to treat IBD. However, many people are intolerant or allergic to it. Therefore, 5-ASA drugs, like Colazal, are commonly used as an alternative.

Studies comparing sulfasalazine to 5-ASA drugs (including Colazal) found that both medications were similarly effective in treating ulcerative colitis. Colazal may be better tolerated, as fewer people taking it in the studies withdrew due to adverse side effects compared with those taking sulfasalazine. Side effects were more common with sulfasalazine compared with 5-ASAs.

Other oral 5-ASA drugs include: 

  • Lialda, Delzcol, Apriso, Pentasa (mesalamine)
  • Dipentum (olsalazine)

Topical mesalamine (available as a suppository or enema) is generally used before an oral 5-ASA, like Colazal. However, when topical treatment does not work, people may combine topical mesalamine with an oral 5-ASA. 

Frequently Asked Questions

  • How does Colazal work?

    Colazal works as an anti-inflammatory agent. When taken, balsalazide is converted into mesalamine (the active metabolite) in the colon, which reduces bowel inflammation and improves ulcerative colitis symptoms like diarrhea and stomach pain.

  • What side effects can I expect while taking Colazal?

    The most common side effects of Colazal include headache, abdominal pain, nausea, vomiting, diarrhea, respiratory infections, and joint aches or pains.

  • How does Colazal compare to other oral 5-ASAs?

    Colazal is similar in efficacy and tolerability to mesalamine and olsalazine. They are available in various formulations, ranging from once-daily regimens to multiple daily dosing options. The convenience of dosing may be necessary for selecting a drug regimen that works for your lifestyle.

  • What is the best way for kids to take Colazal if they can’t swallow capsules?

    Colazal capsules may be opened and the contents sprinkled on a small amount of applesauce. Consume the applesauce mixture immediately, and do not store any extra for future use. Brush teeth afterward to prevent tooth staining.

How Can I Stay Healthy While Taking Colazal?

In addition to taking your medications as prescribed, you can take other steps to help control your ulcerative colitis symptoms.

Making changes to what you eat is one way to manage and prevent flare-ups. Pay attention to how your body reacts to certain foods and identify those that make you feel worse.

Foods that may potentially make your symptoms worse include:

  • Insoluble fiber foods, like raw green vegetables, whole nuts, and whole grains
  • Lactose found in dairy items such as milk and cheese.
  • Sugary foods, such as pastries, candy, or juices
  • High-fat foods, including butter and fatty, fried, or greasy meals
  • Alcohol and caffeinated beverages

You can also try eating smaller meals to hep aid digestion. Consider consulting a registered dietitian nutritionist to develop an eating plan that works for you.

Carefully monitor your ulcerative colitis symptoms when starting Colazal. While it is used to induce and maintain remission of ulcerative colitis, a small number of people have reported worsening or exacerbation of symptoms caused by Colazal. If you suspect this is happening to you, contact your healthcare provider for advice.

Medical Disclaimer

Verywell Health’s drug information is meant for educational purposes only and is not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.


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