Methotrexate: Uses, How to Take, Dosing & Side Effects

Updated in March 2024

Methotrexate is a medicine that is typically indicated for the treatment of autoimmune diseases, such as rheumatoid arthritis or severe psoriasis. It can also be prescribed as chemotherapy for the treatment of cancers like  leukemia, lymphoma, lung cancer or breast cancer.

This medicine works by inhibiting the metabolism of folic acid, which is essential for DNA synthesis, and therefore prevents the multiplication of cancer cells and tumors. When used in low doses, it has an anti-rheumatic and immunosuppressive effect, which can help to reduce the symptoms of rheumatoid arthritis or severe psoriasis.

Methotrexate can be obtained in pharmacies in the form of tablets, or administered in hospital as an IV solution. It should be used as prescribed by your doctor.

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Common uses

Methotrexate can be prescribed for the treatment of:

  • Severe or active flare-ups of rheumatoid arthritis
  • Severe psoriasis
  • Gestational trophoblastic diseases
  • Acute lymphocytic leukemia
  • Meningeal leukemia
  • Non-Hodgkin's lymphoma
  • Burkitt's Lymphoma
  • Small cell lung cancer
  • Breast cancer
  • Head and neck cancer
  • Osteosarcoma

Methotrexate can also be beneficial for the palliative treatment of solid tumors that cannot be operated on surgically.

How to take

The way to use methotrexate varies depending on its presentation, and includes:

1. Methotrexate 2.5 mg tablet

Methotrexate tablets are taken orally with a glass of water, before or after meals, at the times established by the doctor. It is important to wash your hands thoroughly after handling the tablet.

The dosage of methotrexate tablets varies depending to the condition being treated and includes:

  • Rheumatoid arthritis: the normally recommended initial dose is 7.5 mg taken as a single dose, once a week. This dose can also be broken up, with one 2.5 mg tablet, every 12 hours for three doses, once a week,. Methotrexate doses can be adjusted by the doctor according to the response to treatment, and should not exceed a total weekly dose of 20 mg.
  • Severe psoriasis: the normally recommended initial dose is 10 to 25 mg taken as a single dose once a week, or one 2.5 mg tablet taken every 12 hours for three doses, once a week. These doses can be adjusted by the doctor and titrated to up to 30 mg per week, depending on the response to treatment.

Methotrexate doses should be directed by the doctor. Once the most effective dose for treatment is achieved, the doctor can reduce the dose to the lowest therapeutic dose possible.

For rheumatoid arthritis, methotrexate generally takes 3 to 6 weeks to take effect. This response to treatment should be monitored by a doctor.

It is important to note that methotrexate tablets should generally only be taken once a week. Daily use of this medicine can cause serious side effects that can be life-threatening.

2. Injectable methotrexate

Injectable methotrexate for the treatment of cancer can be administered by a nurse directly into the vein (IV) or muscle (IM). It can also be administered into the spinal canal by a doctor. 

The therapeutic dose range of methotrexate for cancer treatment can vary greatly,  and depends on the type of cancer to be treated. Dosing should be calculated by the doctor according to weight and body surface area.

Possible side effects

The most common side effects that may occur during treatment with methotrexate are severe headache, neck stiffness, nausea, vomiting, fever, redness of the skin, increased uric acid and reduced sperm count, and the appearance of ulcers in the mouth. , inflammation of the tongue and gums, diarrhea, reduction in white blood cell and platelet counts, kidney failure and pharyngitis.

In addition, methotrexate can cause liver toxicity, which can be seen through symptoms such as bloating in the belly, pain in the upper right side of the belly, nausea, loss of appetite, dark urine, pale stools or yellowish skin and eyes. You should immediately notify your doctor or seek the nearest emergency room if these symptoms appear.

Methotrexate can also cause serious side effects, such as ARTICLE NOT FOUND IN EN: Stevens-Johnson syndrome or toxic epidermal necrolysis, characterized by severe destruction and peeling of the skin.

This medicine can also increase the risk of infections, which can be noticed through symptoms such as fever, chills, pale skin, cough, difficulty breathing, pain or burning sensation when urinating, sore throat or mouth ulcers or abdominal pain, for example. In these cases, you should contact your doctor immediately.

Care during treatment

There are some precautions that are important to consider when being treated with methotrexate, such as:

  • Attend regular medical appointments as scheduled to monitor the effectiveness of treatment and to identify any possible side effects.
  • Take folic acid supplements as prescribed by your doctor. You should not take folic acid on the same day as taking or receiving a dose of methotrexate, as folic acid can decrease the action of methotrexate.
  • Do not increase or decrease the dose of the methotrexate tablet without being instructed to do so by your doctor.
  • Do not stop treatment with methotrexate on your own.
  • Avoid drinking alcohol.
  • Avoid taking any new medications on your own and without medical advice.
  • Only receive vaccines if approved by your doctor, as some vaccines with active or attenuated viruses are contraindicated during treatment.
  • Wash your hands frequently, with water and a mild soap, especially before and after going to the bathroom, eating, cooking, touching animals, gardening or changing a child's diaper, for example.
  • Wash vegetables and fruits thoroughly before eating.
  • Avoid touching surfaces and touching your eyes, mouth or nose.
  • Avoid contact with people who have infections, as methotrexate can reduce the action of the immune system and increase your risk for an infection.
  • Apply sunscreen SPF 30 or higher, even on cloudy days, as the skin becomes more sensitive to the sun during treatment.
  • Use effective contraceptive methods during treatment with methotrexate and for at least 6 months after finishing treatment. The use of contraceptive methods after treatment with methotrexate may need to last for up to 1 year due to lingering side-effects. This duration should be guided by your doctor.
  • Do not breastfeed during treatment with methotrexate, and for at least 1 week after finishing treatment.

In addition, the doctor may also ordered additional tests as part of the monitoring of treatment. Some tests include a complete blood count, serum creatinine, liver function tests and kidney function tests and pulmonary function tests.

It is important to follow all recommendations as indicated by your doctor to prevent any side effects that may arise during treatment with methotrexate.

Contraindications for use

Methotrexate should not be used by people who are allergic to methotrexate or any component of the formulation, during breastfeeding, or by people with a compromised immune system, severe liver or kidney dysfunction and changes in blood cells such as reduced blood cell counts. white blood cells, red blood cells and platelets.

Furthermore, methotrexate should not be taken during pregnancy as it can cause serious defects in the fetus. Furthermore, the use of methotrexate can cause miscarriage or death of the baby. Methotrexate should never be used if a woman is pregnant or is planning a pregnancy