Methotrexate

This leaflet has been written to help you understand more about methotrexate. It explains what it is, how it works, how it is used to treat skin conditions, and where more information can be found about it.

Methotrexate is a type of medicine called an immunosuppressant. This means it suppresses the body’s immune system and lowers immunity. The immune system is essential in fighting infections, but sometimes immune system cells mistakenly attack the body’s healthy tissues, triggering long-term inflammation. Methotrexate reduces the inflammation caused by your condition by dampening down the activity of these cells in the immune system.

Methotrexate is used to treat several inflammatory conditions, including psoriasis, psoriatic arthritis, various types of eczema, pemphigoid, pemphigus, sarcoidosis, scleroderma, and dermatomyositis. It is not a painkiller, but as a result of reducing the inflammation caused by your condition, you may notice a reduction in pain.

After starting methotrexate, it may take 3-12 weeks before significant improvement in the condition is noticed.

Methotrexate is usually taken in tablet form once a week and should be taken on the same day each week. It should never be taken every day. The tablets are taken with food and should be swallowed whole, not crushed or chewed. Methotrexate may also be given once a week by injection – either subcutaneous (an injection under the skin), or intramuscular (an injection into a muscle, for example into the buttocks or thigh). 

If methotrexate is not taken on the usual day, it can be taken within 48 hours. However, if more than three days late, methotrexate should not be taken that week. The next dose should be taken on a usual day the following week.

Dermatologists usually prescribe 2.5 mg strength tablets of methotrexate. These tablets must not be confused with the 10 mg tablets, which look similar but are clearly of much higher strength. Care should be taken to make sure that the correct dose and strength has been prescribed and dispensed to you. You must always check the dose and strength with your chemist or doctor before taking methotrexate. 

The doctor will advise you of the appropriate weekly dose. Usually, a small dose is prescribed at first and then gradually increased until methotrexate is effective at a safe dose. The amount will be adjusted according to the response to treatment and any side effects experienced.

Methotrexate can cause nausea, tiredness, diarrhea, or mouth ulcers. Rarely hair loss and rashes may occur. Methotrexate can affect the white blood cell count so that fewer white blood cells are produced (bone marrow suppression). You will be more prone to develop infections such as chest infections.

It is essential to see a doctor if any of the following symptoms occur:  a sore throat, fever, or any other symptoms or signs of infection

• Mouth ulcers
• Unexplained bruising or bleeding from the gums
• Nausea, vomiting, abdominal pain, or dark urine
• Breathlessness or cough

Folic acid is frequently recommended as a vitamin supplement when taking methotrexate because it may reduce the incidence of side effects such as nausea.

Liver and lung fibrosis are rare complications that may occur when the methotrexate has been taken for several years.

If you have not had chickenpox previously and come into contact with someone who has chickenpox or a shingles infection, or if you develop chickenpox or shingles while you are taking methotrexate, a doctor should be seen immediately as specialist treatment may be needed.

The ‘live’ vaccines, such as MMR (measles, mumps, rubella), polio, shingles, and yellow fever, are no longer contraindicated in people taking methotrexate. This means that you may be able to have these. But the guidelines advise that your doctors should decide your suitability for these vaccines on an individual basis. 

If you never had chickenpox, your doctor may recommend vaccination against this before starting methotrexate. If this was not possible and you come into contact with a person with chickenpox or shingles while you are taking methotrexate, then you should go to your doctor straight away as you may need special preventative treatment.  Yearly ‘flu’ (influenza) and five-yearly pneumococcal vaccines are safe and should ideally be given to everybody on methotrexate.

Methotrexate can reduce fertility in men, especially at higher doses, and is likely to harm an unborn baby. Women must not take methotrexate during pregnancy. 

Men and women should take adequate contraceptive precautions while taking methotrexate and at least six months after stopping methotrexate.

If you plan and become pregnant while taking methotrexate, discuss it with a doctor as soon as possible. You must not breastfeed if you are taking methotrexate.

Can alcohol drink when taking methotrexate?

Alcohol interacts with methotrexate. Both alcohol and methotrexate can potentially damage the liver. 

Some drugs interact with methotrexate, and this can be dangerous. Always tell any doctor, nurse, or pharmacist treating you that you are taking methotrexate. Special care is needed with non-steroidal anti-inflammatory drugs, such as aspirin or ibuprofen. Anti-inflammatory medications should only be taken if the doctor prescribes them.

Paracetamol preparations are generally safe to take. Do not take ‘over-the-counter’ herbal or vitamin preparations without discussing this with the doctor, nurse, or pharmacist. Antibiotics containing trimethoprim must always be avoided.