Sulfasalazine is an anti-inflammatory drug that reduces pain and swelling in the body. It is a type of DMARD, which means it can help treat those with progressive, inflammatory joint conditions.

In the United States, doctors use sulfasalazine to reduce the symptoms of rheumatoid arthritis (RA), ulcerative colitis, inflammatory bowel disease, and other chronic conditions. The Food and Drug Administration (FDA) has not approved its use for psoriatic arthritis (PsA), but doctors can still prescribe it for off-label use.

In this article, we look at the potential benefits and risks of taking sulfasalazine for PsA.

A person in a white shirt holding a bottle of sulfasalazine for psoriatic arthritis in one hand, and a white mobile device in the other hand.Share on Pinterest
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Sulfasalazine is an odorless and tasteless yellow-brown powder. It is a combination of two components: salicylate and sulfa. According to a 2020 review, the salicylate component acts as an anti-inflammatory agent, and the sulfa component has antimicrobial properties.

In the U.S., it is an FDA-approved drug for treating RA, polyarticular juvenile idiopathic arthritis, and ulcerative colitis. One of its off-label uses is the treatment of PsA.

PsA is a chronic, inflammatory form of arthritis that causes painful, swollen joints, as well as skin and nail symptoms. There is no cure, but treatment can slow the progression of the disease and improve a person’s quality of life.

In 2018, the American College of Rheumatology recommended TNF inhibitors as a possible initial treatment for PsA. However, doctors can also try other drugs, including full doses of nonsteroidal anti-inflammatory drugs (NSAIDs). They may consider sulfasalazine if someone:

  • does not have severe symptoms
  • prefers pills to injections
  • has other conditions that prevent them from taking a TNF inhibitor, such as recurring infections

According to a 2021 review, older clinical trials showed that sulfasalazine had a “modest favorable effect” on bone and muscle symptoms in people with psoriatic arthritis. Studies from the early 2000s found that the drug had anti-inflammatory properties.

The research to date on sulfasalazine for PsA is not as strong as it is for other PsA drugs. It may be effective for some, but overall, more high quality and up-to-date research is necessary to determine how well it works.

The most common side effects of sulfasalazine include:

  • nausea
  • indigestion
  • vomiting
  • no desire to eat
  • headaches
  • skin rash, which could include hives or blue discoloration
  • fertility problems in males, although this is reversible and returns to normal within months of stopping the medication

Less common side effects include fever, dizziness, increased sensitivity to the sun, and orange-yellow discoloration of the skin or urine.

Sulfasalazine has some risks, and certain people should not take it. Doctors are cautious about prescribing sulfasalazine to people with the following conditions:

  • intestinal or urinary obstruction
  • porphyria
  • liver disease, including hepatitis infections
  • kidney damage
  • aplastic anemia
  • fibrosing alveolitis
  • bronchial asthma
  • severe allergies to sulfa or salicylates, e.g., aspirin

There are no official warnings for sulfasalazine use during pregnancy. However, there are no well-controlled studies on the use of sulfasalazine in pregnant people. The leaflet for Azulfidine, a slow-release sulfasalazine drug, suggests refraining from its use during pregnancy unless absolutely necessary.

In rare cases, people can have serious adverse reactions to sulfasalazine, including:

  • severe allergic reactions
  • low white blood cell count, called leukopenia
  • low platelet count, or thrombocytopenia
  • hemolytic anemia
  • changes in liver function
  • toxic epidermal necrosis, a life threatening skin condition

People who take sulfasalazine require regular tests to monitor the liver, kidneys, and blood for signs that the drug is negatively affecting them. Anyone with signs of serious adverse effects, such as skin blistering, should speak with a doctor immediately.

Sulfasalazine and methotrexate are both disease-modifying antirheumatic drugs (DMARDs) that can reduce inflammation and slow the progression of some types of arthritis. Methotrexate is more effective than sulfasalazine for treating inflammation. However, the biologics, which include TNF inhibitors, are more effective for treating PsA.

A 2020 study compared treatment with mainly sulfasalazine and methotrexate in 187 people with PsA. The researchers found that methotrexate performed better than sulfasalazine as a first-line treatment but that it caused more side effects.

However, this study may be flawed as the number of participants taking each drug was imbalanced: 163 people used methotrexate and only 21 used sulfasalazine; the other 3 used leflunomide.

According to a 2021 overview, the dose of sulfasalazine for PsA is usually 500 milligrams (mg) per day, but this can rise to 2–3 grams.

Doctors may start people who are sensitive to the drug on a much lower dose of 50–250 mg, doubling it every 4–7 days until reaching a level that is effective. Doctors can adjust the final dose according to the person’s response, tolerance, and medical history.

It helps to remember that sulfasalazine is a slow-acting drug. Most people only start noticing its effects about 6–8 weeks after they begin the medication. This can lead people to discontinue the drug too early. If a person is concerned that their dosage is not working, they should first speak with a doctor about this.

Regular monitoring from a doctor is an essential part of sulfasalazine treatment. However, a person must report the following side effects to a doctor immediately:

  • signs of infection, such as a fever or sore throat
  • unexplained bruising or bleeding
  • ringing in the ears, called tinnitus

A person should call 911 or the number of the nearest emergency department if someone takes more sulfasalazine than they should, or if they develop any of the following:

  • skin blistering
  • swelling of the mouth or airways
  • difficulty breathing

According to the United Kingdom charity Versus Arthritis, people can usually carry on taking NSAIDs while using sulfasalazine, but they should only start any new medication or supplement after first speaking with a doctor.

Sulfasalazine is a DMARD that may help reduce the symptoms and progression of PsA. The FDA has not approved sulfasalazine as a PsA treatment, so doctors prescribe it for off-label use.

Sulfasalazine can cause side effects and has some risks, so a medical professional should monitor someone taking it via regular checkups and blood tests.