In the U.S.—

In Canada—

Another commonly used name is amethopterin.

• Antipsoriatic, systemic
• Antirheumatic, disease-modifying

Methotrexate ( meth-o-TREX-ate) belongs to the group of medicines known as antimetabolites. It is used to treat psoriasis and rheumatoid arthritis. It may also be used for other conditions as determined by your doctor.

Methotrexate blocks an enzyme needed by the cell to live. This interferes with the growth of certain cells, such as skin cells in psoriasis that are growing rapidly. Since the growth of normal body cells may also be affected by methotrexate, other effects will also occur. Some of these may be serious and must be reported to your doctor. Other effects, like hair loss, may not be serious but may cause concern. Some effects may not occur for months or years after the medicine is used.

Before you begin treatment with methotrexate, you and your doctor should talk about the good this medicine will do as well as the risks of using it.

Methotrexate is available only with your doctor's prescription, in the following dosage forms:

Oral
• Tablets (U.S. and Canada)

Parenteral
• Injection (U.S. and Canada)

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For methotrexate, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to methotrexate.

Pregnancy—There is a good chance that this medicine may cause birth defects if either the male or female is taking it at the time of conception or if it is taken during pregnancy. Methotrexate may cause harm or even death of the fetus. In addition, this medicine may rarely cause temporary sterility.

Methotrexate is not recommended during pregnancy. Be sure that you have discussed this with your doctor before taking this medicine. It is best to use some kind of birth control while you are taking methotrexate. Tell your doctor right away if you think you have become pregnant while taking methotrexate.

Breast-feeding—Tell your doctor if you are breast-feeding or if you intend to breast-feed during treatment with this medicine. Because methotrexate may cause serious side effects, breast-feeding is generally not recommended while you are taking it.

Children—Newborns and other infants may be more sensitive to the effects of methotrexate. However, in other children it is not expected to cause different side effects or problems than it does in adults.

Older adults—Side effects may be more likely to occur in the elderly, who are usually more sensitive to the effects of methotrexate.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking methotrexate, it is especially important that your health care professional know if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicine. They should also be told if you have ever been treated with x-rays or cancer medicines or if you drink alcohol.

• Alcohol abuse (or history of)—Increased risk of unwanted effects on the liver

• Chickenpox (including recent exposure) or
• Herpes zoster (shingles)—Risk of severe disease affecting other parts of the body

• Colitis

• Disease of the immune system
• Folate deficiency—May increase the chance of side effects

• Infection—Methotrexate can reduce immunity to infection

• Intestine blockage or
• Kidney disease or
• Liver disease—Effects may be increased because of slower removal of methotrexate from the body

• Mouth sores or inflammation or
• Stomach ulcer—May be worsened

Take this medicine only as directed by your doctor. Do not take more or less of it, and do not take it more often than your doctor ordered. The exact amount of medicine you need has been carefully worked out. Taking too much may increase the chance of side effects, while taking too little may not improve your condition.

Methotrexate may cause nausea. Even if you begin to feel ill, do not stop using this medicine without first checking with your doctor. Ask your health care professional for ways to lessen these effects. If you begin vomiting, check with your doctor.

If you vomit shortly after taking a dose of methotrexate, check with your doctor. You will be told whether to take the dose again or to wait until the next scheduled dose.

Dosing—

The dose of methotrexate will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of methotrexate. If your dose is different, do not change it unless your doctor tells you to do so.

The number of tablets that you take or doses of injection that you use depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are taking methotrexate.

• For oral dosage form (tablets):
  • For psoriasis :
    • Adults—2.5 to 5 milligrams (mg) every twelve hours for three doses once a week, or 10 to 25 mg once a week. Your doctor may increase the dose as needed.
    • Children—Dose must be determined by your doctor.
  • For rheumatoid arthritis:
    • Adult—2.5 to 5 mg every twelve hours for three doses once a week, or 7.5 mg once a week. Your doctor may increase the dose as needed.
    • Children—Dose must be determined by your doctor.
• For injection dosage form:
  • For psoriasis:
    • Adults—To start, 10 mg injected into a muscle or vein once a week. Your doctor may increase the dose as needed.
    • Children—Dose must be determined by your doctor.

Missed dose—

If you miss a dose of this medicine, do not take the missed dose at all and do not double the next one. Instead, go back to your regular dosing schedule and check with your doctor.

Storage—

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly and to check for unwanted effects.

Do not drink alcohol while using this medicine. Alcohol can increase the chance of liver problems.

Some patients who take methotrexate may become more sensitive to sunlight than they are normally. When you first begin taking methotrexate, avoid too much sun and do not use a sunlamp until you see how you react to the sun, especially if you tend to burn easily. In case of a severe burn, check with your doctor. This is especially important if you are taking this medicine for psoriasis because sunlight can make the psoriasis worse.

Do not take medicine for inflammation or pain (aspirin or other salicylates, diclofenac, diflunisal, fenoprofen, ibuprofen, indomethacin, ketoprofen, meclofenamate, mefenamic acid, naproxen, phenylbutazone, piroxicam, sulindac, suprofen, tolmetin) without first checking with your doctor. These medicines may increase the effects of methotrexate, which could be harmful.

While you are being treated with methotrexate, and after you stop treatment with it, do not have any immunizations (vaccinations) without your doctor's approval. Methotrexate may lower your body's resistance and there is a chance you might get the infection the immunization is meant to prevent. In addition, other persons living in your household should not take or should not have recently taken oral polio vaccine since there is a chance they could pass the polio virus on to you. Also, avoid other persons who have taken oral polio vaccine. Do not get close to them, and do not stay in the same room with them for very long. If you cannot take these precautions, you should consider wearing a protective face mask that covers the nose and mouth.

Methotrexate can lower the number of white blood cells in your blood temporarily, increasing the chance of getting an infection. It can also lower the number of platelets, which are necessary for proper blood clotting. If this occurs, there are certain precautions you can take, especially when your blood count is low, to reduce the risk of infection or bleeding:

• If you can, avoid people with infections. Check with your doctor immediately if you think you are getting an infection or if you get a fever or chills, cough or hoarseness, lower back or side pain, or painful or difficult urination.
• Check with your doctor immediately if you notice any unusual bleeding or bruising; black, tarry stools; blood in urine or stools; or pinpoint red spots on your skin.
• Be careful when using a regular toothbrush, dental floss, or toothpick. Your medical doctor, dentist, or nurse may recommend other ways to clean your teeth and gums. Check with your medical doctor before having any dental work done.
• Do not touch your eyes or the inside of your nose unless you have just washed your hands and have not touched anything else in the meantime.
• Be careful not to cut yourself when you are using sharp objects such as a safety razor or fingernail or toenail cutters.
• Avoid contact sports or other situations where bruising or injury could occur.

Along with their needed effects, medicines like methotrexate can sometimes cause unwanted effects such as blood problems, kidney problems, stomach or liver problems, loss of hair, and other side effects. These and others are described below. Also, because of the way these medicines act on the body, there is a chance that they might cause other unwanted effects that may not occur until months or years after the medicine is used. These delayed effects may include certain types of cancer, such as leukemia. Discuss these possible effects with your doctor.

Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

• Less common
  • Diarrhea;  reddening of skin;  sores in mouth and on lips;  stomach pain 
  
  

• Rare
  • Black, tarry stools;  blood in urine or stools;  blurred vision;  chest pain;  convulsions (seizures);  cough or hoarseness;  dead or loose skin layers;  fever or chills;  lower back or side pain;  painful or difficult urination ;  painful peeling of skin patches;  pinpoint red spots on skin;  red blisters, ulcers on the lip, mouth, eye, nasal passages, and genital area;  reddening of the skin with or without hair loss; shortness of breath;  sloughing of skin , muscle and bone;  unusual bleeding or bruising 
  
  

Check with your doctor as soon as possible if any of the following side effects occur:

• Rare
  • Back pain;  dark urine;  dizziness;  drowsiness;  headache;  unusual tiredness or weakness ;  yellow eyes or skin 
  
  

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

• Less common or rare
  • Acne;  boils;  loss of appetite;  nausea or vomiting;  pale skin;  skin rash or itching 
  
  

This medicine may cause a temporary loss of hair in some people. After treatment with methotrexate has ended, normal hair growth should return.

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.

Once a medicine has been approved for marketing for a certain use, experience may show that it is also useful for other medical problems. Although these uses are not included in product labeling, methotrexate is used in certain patients with the following medical conditions:

• Psoriatic arthritis
• Systemic dermatomyositis
• Seronegative arthritides

Other than the above information, there is no additional information relating to proper use, precautions, or side effects for these uses.