Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.
Anemia: Methotrexate may cause low levels of red blood cells. If you experience symptoms of reduced red blood cell count (anemia) such as shortness of breath, feeling unusually tired, or pale skin, contact your doctor as soon as possible.
Bleeding: Methotrexate may cause a reduced number of platelets in the blood, which can make it difficult to stop cuts from bleeding. If you notice any signs of bleeding, such as frequent nosebleeds, unexplained bruising, or black and tarry stools, notify your doctor as soon as possible. Your doctor will order routine blood tests to make sure potential problems are caught early.
Blood counts: Methotrexate can cause a decrease in the number of white blood cells, red blood cells, and platelets in your blood, especially when higher doses are used to treat cancer. This may increase your risk of bleeding or infections. Your doctor will monitor your blood counts with regular blood tests.
If you are using this medication to treat cancer and already have a blood disorder such as anemia, reduced white blood cell counts, or reduced platelet counts, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Cancer: This medication may cause lymphoma (cancer of the immune cells) that may resolve when the medication is stopped. Your doctor will monitor for this.
Dizziness/fatigue: This medication may cause dizziness and fatigue. Do not drive or operate machinery until you are certain that taking this medication does not impair your ability to safely perform these tasks.
Hepatitis B and C infection: Methotrexate can cause reactivation of hepatitis B and C infections or worsening of existing infections. If you have a history of infection with hepatitis B or C virus, let your doctor know before starting this medication.
Infection: As well as killing cancer cells, methotrexate can reduce the number of cells that fight infection in the body (white blood cells). If possible, avoid contact with people with contagious infections. Tell your doctor immediately if you notice signs of an infection, such as fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness.
If you are using this medication to treat rheumatoid arthritis and have an infection, talk to your doctor about whether you need to temporarily stop this medication until the infection resolves.
Kidney function: Reduced kidney function or kidney disease may cause this medication to build up in the body. If you have reduced kidney function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. If you are using this medication to treat cancer, your doctor may want you to drink extra fluids to help prevent kidney problems.
Liver problems: Methotrexate can cause liver problems. Your doctor will check your liver function with blood tests before starting this medication and regularly during treatment. If you have liver problems or reduced liver function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Do not drink alcohol while you are taking this medication as this can increase the chance of liver problems.
Lung problems: Lung inflammation (interstitial lung disease), causing difficulty breathing has occurred in some people taking this medication. This complication can be serious and sometimes fatal. If you experience new or worsening shortness of breath or non-productive cough (with or without fever) at any time while you are taking methotrexate, contact your doctor immediately.
Nausea: Methotrexate may sometimes cause nausea. If you feel ill after taking methotrexate, do not stop taking the medication without first talking with your doctor. Your doctor or pharmacist may be able to help you with ways to reduce the nausea associated with taking this medication.
Stomach and intestinal problems: If you have stomach or intestinal ulcers or ulcerative colitis, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Seizures: Methotrexate has been reported to cause a condition called leukoencephalopathy that often causes seizures. Leukoencephalopathy is a rare disorder that causes nerve damage in the brain. Other symptoms of this disorder include memory loss, vision loss, trouble thinking, or difficulty walking. If you experience any of these, contact your doctor immediately.
Sun sensitivity: You may be more sensitive to the sun while using this medication. Avoid excessive sun exposure and do not use sunlamps or sun beds until you know how this medication affects your skin.
Tumour Lysis Syndrome: Methotrexate, like many other cancer medications, causes many cancer cells to be suddenly killed when treatment is first started. This can overwhelm the body with waste products from the cells. As a result, the body may not be able to keep up with getting rid of all the waste. When this happens, you may experience nausea, shortness of breath, cloudy urine, or joint pain. This is called tumour lysis syndrome. Your doctor may prescribe medications to help your body get rid of the waste products. Make sure you understand how to use these medications and report any of these signs or symptoms to your doctor immediately.
Vaccines: Vaccines may be ineffective if given during treatment with methotrexate. Live virus vaccines (e.g., smallpox, measles, mumps, rubella, chickenpox, shingles) are not recommended during treatment with methotrexate.
Pregnancy: There is a possibility of birth defects if either partner is using methotrexate at the time of conception. If it is used during pregnancy, methotrexate may also cause birth defects or harm the baby.
Effective birth control should be practiced if either partner is using this medication, including for a period of time after the medication is stopped. Talk to your doctor about how long you should wait to become pregnant after you or your partner stop taking methotrexate. If you become pregnant while taking this medication, contact your doctor immediately.
If you have rheumatoid arthritis or psoriasis, you should not use this medication if you are pregnant. If you might be pregnant, do not start methotrexate until you know for sure that you are not pregnant.
Breast-feeding: Due to the potential for serious harm to a baby if they are exposed to this medication, women who are using methotrexate should not breast-feed.
Children: Methotrexate has been used to treat cancer in children. Methotrexate has also been used under close supervision of a doctor to treat other conditions in children, although the safety and effectiveness have not been clearly determined.
Seniors: If you are a senior, you may be more at risk of experiencing side effects (including serious ones) and your doctor will monitor you very closely while you are using this medication.