Like all medicines, sulfasalazine can cause side effects in some people, but many people have no side effects or only minor ones.
You're more likely to have side effects if you're taking a high dose of sulfasalazine.
Sulfasalazine can turn your pee orange. This is harmless and nothing to worry about.
It's unusual, but sulfasalazine can also stain certain types of soft contact lenses. Single-use daily contact lenses are not affected.
Common side effects of sulfasalazine
Side effects of sulfasalazine can vary depending on whether you're taking it as a tablet, suppository or liquid. Check the leaflet that comes with your medicine before taking or using it.
These common side effects happen in more than 1 in 100 people. There are things you can do to help cope with them:
Indigestion and heartburn
It might help to take your sulfasalazine a few minutes before or after a meal.
If you need something to ease the discomfort, try taking an antacid. However, if you take an antacid, take it at least 2 hours before or at least 2 hours after you take sulfasalazine.
Feeling sick (nausea)
Stick to simple meals and do not eat rich or spicy food. It might help to take your sulfasalazine after you've eaten.
Diarrhoea
Drink lots of fluids, such as water or squash, to avoid dehydration. Speak to a pharmacist if you have signs of dehydration such as peeing less than usual or having dark strong-smelling pee. Do not take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor.
If you take the combined contraceptive pill or the progestogen-only pill and you have severe, watery diarrhoea, or any diarrhoea that lasts for more than 24 hours, your contraception may not protect you from pregnancy. Check the pill packet for advice.
Being sick (vomiting)
Stick to simple meals and do not eat rich or spicy food. It might help to take your sulfasalazine after you've eaten.
Drink plenty of fluids, such as water or squash, to avoid dehydration. Take small frequent sips if you're being sick. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee.
If you take the combined contraceptive pill or the progestogen-only pill and you're being sick, your contraception may not protect you from pregnancy. Check the pill packet for advice.
Stomach (abdominal) pain
Try to rest and relax. It can help to eat and drink slowly and have smaller and more frequent meals. Putting a heat pad or covered hot water bottle on your stomach may also help. If you're in a lot of pain, speak to your pharmacist or doctor.
Feeling dizzy
Sit down for a while until the feeling passes. Do not drive, cycle or use tools or machinery until you feel better.
Headache, joint aches and pains
Drink plenty of water and ask your pharmacist to recommend a painkiller. If the headache or pains continue or are severe, and taking a painkiller does not help, tell your doctor.
Cough, sore mouth or changes in the way things taste (a metallic taste and changes in the way sweet things taste)
Try chewing sugar-free gum. If you're coughing try having frequent sips of water or other unsweetened drinks.
Difficulty sleeping
Avoid having a big meal, smoking, or drinking alcohol, tea or coffee in the evening. Try not to watch television or use your mobile phone before going to bed. Instead, try to relax for an hour before bedtime.
Ringing in your ears (tinnitus)
Speak to your doctor if this does not go away or lasts longer than 2 days.
Serious side effects
Skin rashes
Severe skin reactions such as Stevens-Johnson syndrome are a rare side effect of sulfasalazine.
Stevens-Johnson syndrome causes flu-like symptoms, followed by a rash made up of circular patches that are darker in the middle and lighter around the outside. The rash spreads and forms blisters. The affected skin eventually dies and peels off.
This is more likely to happen in the first month of taking sulfasalazine.
You're more likely to get Stevens-Johnson syndrome if:
- you've had it before after taking sulfasalazine or certain other medicines
- you have a weakened immune system – for example, from having a condition like HIV or AIDS, or treatments like chemotherapy
- a close family member has had Stevens-Johnson syndrome
To help reduce the chance of you getting a rash that could be confused with Stevens-Johnson syndrome, it's best to not try any new medicines or food during the first 3 months of treatment with sulfasalazine.
It's also best to not start taking sulfasalazine within 2 weeks of a viral infection, vaccination, or rash caused by something else.
Immediate action required: Go to A&E now if:
- you get a severe rash with flushing, blisters or ulcers – these can be signs of Stevens-Johnson syndrome or other severe skin reactions
Stop taking sulfasalazine straight away if this happens.
Do not drive to A&E. Ask someone to drive you or call 999 and ask for an ambulance.
Bring all the medicines you take with you.
Serum sickness
Stop taking sulfasalazine and call your doctor or call 111 straight away if you have a high temperature, pains in your joints, swollen glands, an itchy rash and you generally feel unwell. These can be signs of a condition called serum sickness.
Other serious side effects
Other serious side effects are very rare, affecting less than 1 in 10,000 people.
Call a doctor or call 111 straight away if you get:
- a high temperature, chills, a sore throat, ear or sinus pain, a cough, pain when peeing, mouth sores, a wound that will not heal or feeling generally ill – these can be signs of an infection
- a high temperature and sore throat, skin becoming paler than usual, unusual bruising or bleeding, or unusual tiredness or weakness – these can be signs of a blood problem
- change in the amount of pee you produce or pain when peeing – these can be signs of kidney problems
- a fast or irregular heartbeat or feeling much more tired than usual – these can be signs of heart problems
- yellowing of the eyes or skin (this may be less obvious on brown or black skin), dark pee, stomach pain, a high temperature, feeling tired or feeling sick – these can be signs of a serious liver problem
- back or stomach pain, a high temperature, feeling sick (nausea) and being sick (vomiting) – these can be signs of a problem with your pancreas
Immediate action required: Call 999 now if:
- you have chest pain
Do not drive yourself to A&E.
The person you speak to at 999 will give you advice about what to do.
Serious allergic reaction
In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to sulfasalazine.
Immediate action required: Call 999 now if:
- your lips, mouth, throat or tongue suddenly become swollen
- you're breathing very fast or struggling to breathe (you may become very wheezy or feel like you're choking or gasping for air)
- your throat feels tight or you're struggling to swallow
- your skin, tongue or lips turn blue, grey or pale (if you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet)
- you suddenly become very confused, drowsy or dizzy
- someone faints and cannot be woken up
- a child is limp, floppy or not responding like they normally do (their head may fall to the side, backwards or forwards, or they may find it difficult to lift their head or focus on your face)
You or the person who's unwell may also have a rash that's swollen, raised, itchy, blistered or peeling.
These can be signs of a serious allergic reaction and may need immediate treatment in hospital.
Do not drive yourself to A&E.
The person you speak to at 999 will give you advice about what to do.
Other side effects
These are not all the side effects of sulfasalazine. For a full list see the leaflet inside your medicines packet.
Reporting side effects
You can report any suspected side effect using the Yellow Card safety scheme.
Visit the Yellow Card website for more information about reporting side effects.