Azulfidine (Sulfasalazine) Frequently Asked Questions

This Drug May Be Used As A Maintenance Therapy For Ulcerative Colitis

Baby Boy
It's important for everyone who takes sulfasalazine to supplement with folic acid, and especially for women in their childbearing years. Photo © Justyna Furmanczyk

What Is Sulfasalazine?

The drug sulfasalazine is a 5-ASA compound, and is the combination of two substances: sulfapyridine and an aspirin-like compound. It is used to reduce the inflammation in the colon caused by  ulcerative colitis, one form of inflammatory bowel disease (IBD). It is also used  as a maintenance therapy to maintain remission. Sulfasalazine may also be used to treat Crohn's disease, especially when the disease only affects the colon, though there is mounting evidence that it is not effective.

Other conditions for which sulfasalazine might be prescribed include rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, and juvenile idiopathic arthritis.

The most important thing to know about sulfasalazine is that it inhibits the absorption of folic acid. Folic acid is a type of B vitamin that is especially important for women who want to become pregnant or who are pregnant. A lack of folic acid is associated with the development of birth defects, especially of the brain and spine. All people who take sulfasalazine will be advised to take a folic acid supplement, and women of childbearing age may need to take more. Check with your doctor about how much folic acid you should take every day.

How Is Sulfasalazine Taken?

In order for sulfasalazine to be effective, the pills must be swallowed whole and not crushed or chewed. It is usually taken 4 times a day; this typically means at each mealtime and then again before bed.

Sulfasalazine should be taken with a meal or a snack and with plenty of water.

Why Is Sulfasalazine Prescribed?

Sulfasalazine is used as a maintenance drug -- it is helpful in retaining remission but not in supressing a flare-up. It is typically, but not always, used for ulcerative colitis and ulcerative proctitis.

The reason why sulfasalazine helps to treat intestinal inflammation is because it reduces the formation of prostaglandins. Prostaglandins are involved with the promotion of inflammation and pain.

What Do I Do If I Miss A Dose?

If you miss a dose, take it as soon as you remember. If your next dose should be taken soon, just take that dose. Don't double up, or take more than one dose at a time.

Who Should Not Take Sulfasalazine?

Tell your doctor if you have ever had any of the following conditions:

What Are The Side Effects?

Side effects from sulfasalazine are not common. Minor side effects include diarrhea, headache, loss of appetite, upset stomach, vomiting, and stomach pain. Sulfasalazine may also cause urine to turn dark yellow or orange in color, but this is harmless, although it can stain clothing. Serious side effects of sulfasalazine that should be reported to the prescribing physician include pale or jaundiced (yellow) skin or eyes, difficulty swallowing, unusual bleeding or bruising and weakness. See the Azulfidine side effects page for a complete list.

Are There Any Sexual Side Effects?

Sulfasalazine is associated with temporary infertility (oligospermia) in men, which abates after the drug is discontinued.

What Medications Can Sulfasalazine Interact With?

Sulfasalazine is not known to interact with other medications. People who have had an adverse reaction to other sulfa drugs ay also be sensitive to sulfasalazine.

Sulfasalazine can interfere with the body's ability to absorb folic acid. The prescribing physician may recommend folic acid supplements.

Are There Any Food Interactions?

There are no known food interactions with sulfasalazine.

Is Sulfasalazine Safe During Pregnancy?

The FDA has classified sulfasalazine as a type B drug.

The effect that sulfasalazine has on an unborn child has not been studied extensively. Sulfasalazine should only be used during pregnancy if clearly needed. Notify the prescribing doctor if you become pregnant while taking sulfasalazine. Sulfasalazine does pass into breast milk, and could affect a nursing infant.

How Long Can Sulfasalazine Be Taken Safely?

Under the supervision of a physician, sulfasalazine can be safely used long-term.


Akobeng AK. "Crohn's disease: current treatment options." Arch Dis Child. 2008 Sep;93(9):787-792. 7 Feb 2016.

National Center on Birth Defects and Developmental Disabilities. "Plan Ahead: Folic Acid Can Help Prevent Certain Birth Defects." 11 Jan 2016. 7 Feb 2016.

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