As with all medicines, methotrexate can cause some unwanted side effects, although not everyone has them. The following list contains some of the possible side effects of methotrexate:

  • Any medication can cause an allergic reaction. If you have any sudden wheeziness, feel faint, have difficulty in breathing, or swelling of the face, lips or mouth, stop taking methotrexate and seek urgent medical attention.
  • If you have any rash or itching, stop taking your methotrexate and contact your doctor immediately
  • Common side effects at the beginning of treatment with methotrexate can include feeling sick, vomiting and diarrhea. The following suggestions may help:
  1. Taking the folic acid supplement as prescribed
  2. Taking your methotrexate at a different time of day, for example before you go to bed at night

If these side effects persist or are severe, talk to your doctor, who may be able to prescribe you an anti-sickness medication to take before your methotrexate. You may also be able to have your dose altered or to switch from the tablet to the injection if you are taking the oral form.

  • As mentioned earlier, methotrexate affects the immune system, and can increase your risk of infections, some of which may make you seriously ill. Try to avoid close contact with people who have infections, and contact your doctor immediately if you think you have an infection – this includes having a fever, sore throat and achiness
  • In rare cases, methotrexate can affect the lungs. Tell your doctor if you become breathless, have a persistent cough, chest pain or difficulty breathing
  • Methotrexate has been known to damage the liver. Liver damage may occur with very few outward signs, but in some cases people notice a yellowing or discoloration of the skin or whites of the eyes, or develop severe itching of the skin. If this happens, you should contact your doctor immediately. Regular blood tests can show up liver damage, but special scans and a biopsy of the liver are sometimes necessary
  • Rarely, methotrexate can harm the kidneys. Kidney function should be checked along with your blood count and liver tests.
  • Methotrexate can cause bone marrow suppression, which may reduce the number of blood cells made by the bone marrow. It can cause a drop in white blood cells (that fight infection) and platelets (that assist with clotting). If you find that you bruise or bleed easily, have nose bleeds, or have blood spots or rashes on the skin, or have an infection stop taking your methotrexate and contact your doctor immediately. Methotrexate may also cause anaemia (lack of oxygencarrying red blood cells) – your doctor should be able to tell from blood tests whether you have this. There is evidence that immunosuppressants such as methotrexate may also slightly increase the risk of other blood disorders, such as lymphoma (cancer of the lymph glands).
  • Methotrexate can increase the skin’s sensitivity to sunlight, and the risk of developing some types of skin cancer. This can be reduced by wearing hats, light clothing and high SPF sun block
  • Some other side effects of methotrexate are listed below. Seek medical attention if you develop any of these side effects, or notice any other unusual symptoms while on methotrexate:
  1. Skin rash
  2. Swollen glands
  3. Mouth or gum ulcers
  4. Hair loss
  5. Acne
  6. Abdominal pain
  7. Vaginal ulceration
  8. Headache or dizziness or unusual sensations in the head and confusion
  9. Fatigue or drowsiness
  10. Blurred vision
  11. Mobility problems

Overall, it is best to let your doctor or IBD team know about any new symptom you develop while on methotrexate, whenever they occur. Your IBD team should also be able to help with any questions and concerns. Regular blood tests can help to reduce the risk of developing some side effects.