Sulfasalazine

What is sulfasalazine?

Sulfasalazine is a long-term prescription-only treatment for inflammatory and autoimmune conditions. It belongs to a family of drugs known as aminosalicylates which, among other types of medications, are known as disease-modifying anti-rheumatic drugs (DMARDS). These are designed to slow down the progression of some diseases[1]. 

What is sulfasalazine used for?

Sulfasalazine is commonly prescribed for[1]: 

• Ulcerative colitis 

• Crohn’s disease 

• Rheumatoid arthritis 

• Sometimes used off-label for psoriatic arthritis and other inflammatory conditions 

How does sulfasalazine work?

Sulfasalazine helps calm the immune system and reduce inflammation. It is thought to[1]: 

• Block the production of inflammatory chemicals in the gut and joints 

• Suppress immune system overactivity 

• Ease swelling, pain, and tissue damage 

Who can take sulfasalazine?

Sulfasalazine is suitable for most adults and children over 2 years old. It may not be suitable if you[1]: 

• Are allergic to sulfasalazine, sulfonamides, or salicylates 

• Have liver or kidney problems 

• Have porphyria (a rare blood disorder) 

• Have G6PD deficiency 

• Are pregnant or breastfeeding (consult your doctor) 

• Have asthma or frequent infections 

Please tell your doctor or pharmacist about any conditions you may have or medication you take before you start treatment, and always follow the instructions in the Patient Information Leaflet[2].  

What is the typical dosage of sulfasalazine?

Sulfasalazine tablets and suppositories contain 500mg of sulfasalazine. The liquid contains 250mg in 5ml. The dosage depends on the condition being treated, the severity of the disease and how well you tolerate it[1]: 

• Rheumatoid arthritis: start with 500mg once daily, increasing weekly to one tablet 4 times a day (2g per day) or two tablets 3 times a day (3g per day) 

• Ulcerative colitis or IBS: 2 to 4 tablets (or 20 to 40ml liquid) four times a day 

• Children: dose depends on body weight and age 

Always follow your doctor or pharmacist’s instructions for adjusting your dose. 

How do you take sulfasalazine?

Different forms of sulfasalazine have different instructions, but you should always space your doses evenly through the day and drink plenty of fluids to support kidney function. Follow the guidance below[1]: 

• Tablets: swallow whole with water, do not crush or chew 

• Liquid: take with food 

• Suppositories: insert after a bowel movement, usually twice daily 

Remember to always take your medication as prescribed. 

Can you stop taking sulfasalazine?

Do not stop taking sulfasalazine without speaking to your doctor or pharmacist. Stopping suddenly may lead to a flare-up of symptoms. They can help you reduce the dose gradually if needed[1]. 

What do you do if you take too much sulfasalazine?

Taking one extra dose by mistake is unlikely to cause harm. If you take more than one extra dose or feel unwell, contact your doctor, pharmacist, call NHS 111, or go to A&E[1]. 

What do you do if you forget to take sulfasalazine

If you forget to take a dose[1]: 

• Take it as soon as you remember 

• If it's nearly time for your next dose, skip the missed one 

• Do not double the dose to make up for the missed one 

What medicines can’t you take with sulfasalazine?

Sulfasalazine can interact with other medicines. Speak to your doctor first if you take[1]: 

• Digoxin 

• Diabetes medication like metformin 

• Methenamine (used for urinary tract infections) 

• Folic acid (you may need a higher dose) 

• Azathioprine or mercaptopurine 

• Methotrexate 

Always inform your doctor or pharmacist about all medications and supplements you take before you start a new medicine, and follow the instructions in the Patient Information Leaflet[2]. 

What are the side effects of sulfasalazine?

Most people tolerate sulfasalazine well, but side effects can occur. The most common side effects include[1]: 

• Headache, joint aches, and pains 

• Nausea or vomiting 

• Indigestion or heartburn 

• Diarrhoea 

• Stomach pain 

• Dizziness 

• Cough, sore mouth, or taste changes 

• Difficulty sleeping 

• Ringing in your ears 

• Change to the colour of your urine 

The rarer but more serious side effects include[1]: 

• Severe skin reactions such as Stevens-Johnson syndrome - flu-like symptoms, followed by a rash of circular patches that are darker in the middle and lighter on the outside. More likely if you’ve had it before after taking medication, have a weakened immune system, or a close family member has had it 

• Yellowing of the skin or eyes (jaundice) 

• Unexplained bruising or bleeding 

• Severe sore throat or mouth ulcers 

• A high temperature with joint pain, swollen glands, an itchy rash and a general ill feeling as a sign of serum sickness 

• Breathing difficulties 

You should contact your GP if you experience any of these symptoms. In rare cases, the medicine may cause a serious allergic reaction (anaphylaxis). You should call 999 or visit A&E immediately if you believe this is happening[1]. 

Symptoms of anaphylaxis include[1]:  

• Difficulty breathing  

• Tightness in throat and chest  

• Swelling of the tongue or throat  

• Feeling faint or dizzy  

• Blue/grey skin or lips  

• Loss of consciousness 

 If you experience any side effects, including those not listed, you are encouraged to report them via the Yellow Card Scheme or contact your doctor, pharmacist, or nurse. This information is intended as a summary for general awareness and does not replace professional medical advice. 

The information provided in the side effects section is not a comprehensive list of all possible side effects associated with this medication. For a complete list of side effects, please refer to the Patient Information Leaflet (PIL) provided with your medication or consult your healthcare professional[2]. 

Frequently asked questions about sulfasalazine

How long does sulfasalazine take to work? 
It may take 1 to 3 months for arthritis. Effects may appear sooner for bowel conditions[1]. 

Can I drink alcohol on sulfasalazine? 
Yes, in moderation[1]. 

Is sulfasalazine safe in pregnancy? 
Often yes, but folic acid supplements are usually recommended. However, tell your doctor if you are pregnant or are planning to become pregnant.[1]. 

Does sulfasalazine affect fertility? 
It may reduce sperm count temporarily in men[1]. 

What if I get an infection? 
Contact your doctor. Sulfasalazine may reduce your white blood cells, making infections more likely[1]. 

What monitoring is needed? 
You will have your kidneys checked before you start the medication, after the first three months and then annually. You should also expect to have your blood levels and liver function checked for the first three months[1]. 

For the official NHS guide to sulfasalazine, visit their website.