Like all medicines, methotrexate can cause side effects, although not everyone gets them.
Sensitivity to sunlight
Your skin may become very sensitive to sunlight while you’re taking methotrexate. This can cause a reaction that looks and feels like sunburn.
To reduce the chance of this side effect, stay out of bright sun, use a high factor sunscreen (SPF 30 or above) and wear clothes that protect you from the sun. Do not use a sun lamp or sun beds.
Common side effects
These common side effects of methotrexate may happen in more than 1 in 100 people. There are things you can do to help cope with them:
Loss of appetite
Eat when you would usually expect to be hungry. If it helps, eat smaller meals more often than usual. Snack when you're hungry. Have nutritious snacks that are high in calories and protein, such as dried fruit and nuts.
Feeling or being sick
Eat simple meals and do not eat rich or spicy food. If you're being sick, try taking small, frequent sips of water to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee.
If you take contraceptive pills and you're being sick your contraception may not protect you from pregnancy. Check the pill packet for advice.
Stomach pain or indigestion
Try to rest and relax. It can help to eat and drink slowly and have smaller and more frequent meals. For stomach ache, putting a heat pad or covered hot water bottle on your stomach may help.
If you need something to ease the discomfort from indigestion, try taking an antacid.
If you're in a lot of pain, speak to your pharmacist or doctor.
Diarrhoea
Drink lots of fluids, such as water or squash, to avoid dehydration. Signs of dehydration include 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 contraceptive pills and you have severe diarrhoea for more than 24 hours, your contraception may not protect you from pregnancy. Check the pill packet for advice.
Headaches
Rest and drink plenty of water. Do not drink too much alcohol. Do not take non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen. You can try a painkiller such as paracetamol.
Talk to your doctor if headaches last longer than a week or are severe.
Feeling tired or drowsy
Do not drive, cycle or use machinery if you feel tired or drowsy. Speak to your doctor if this does not get better.
Hair loss
This is unlikely to be permanent. If hair loss bothers you, talk to your doctor. They may be able to lower your dose or recommend a different medicine.
Speak to a doctor or pharmacist if the advice on how to cope does not help and a side effect is still bothering you or does not go away.
Serious side effects
Serious side effects are rare and happen in less than 1 in 10,000 people.
Tell your doctor or call 111 immediately if you get:
- yellowing of the whites of your eyes, or yellowing of your skin although this may be less obvious on brown or black skin – these may be signs of liver problems
- a persistent cough, chest pain, difficulty breathing, or you become breathless – these may be signs of inflammation of your lungs
- swollen hands, ankles or feet, changes to how often you pee or not peeing at all – these may be signs of kidney problems
- a high temperature, chills, muscle aches, sore throat – these may be signs of an infection
- bleeding gums, blood in your pee, vomiting blood or unexplained bruising – these may be signs of a blood disorder
Serious allergic reaction
In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to methotrexate.
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.
Long-term side effects
Methotrexate may increase the risk of problems with your liver or lungs, especially if you take a high dose.
However, your doctor will monitor you very closely and any concerns or problems will be found during routine check-ups.
Other side effects
These are not all the side effects of methotrexate. For a full list see the leaflet inside your medicines packet.
You can report any suspected side effect using the Yellow Card safety scheme.