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Generic name: pemetrexed [ pem-e-TREX-ed ]
Brand names: Alimta, Pemfexy
Dosage forms: intravenous powder for injection (1 g; 100 mg; 500 mg; 750 mg), intravenous solution (25 mg/mL)
Drug class: Antimetabolites

Medically reviewed by on Dec 16, 2022. Written by Cerner Multum.

What is pemetrexed?

Pemetrexed is used to treat adults with non-squamous non-small cell lung cancer when the cancer has returned or spread after chemotherapy.

Pemetrexed is also used to treat adults with malignant pleural mesothelioma (a form of lung cancer associated with exposure to asbestos) that cannot be removed by surgery or people are not able to have surgery.

Pemetrexed is sometimes used in combination with other cancer medicines.

Pemetrexed may also be used for purposes not listed in this medication guide.

Pemetrexed side effects

Get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Pemetrexed may cause serious side effects. Call your doctor at once if you have:

  • little or no urination;

  • new or worsening cough, fever, trouble breathing;

  • swelling, redness, or blistering of skin that was treated with radiation in the past; or

  • low blood cell counts--fever, chills, tiredness, mouth sores, skin sores, easy bruising, unusual bleeding, pale skin, cold hands and feet, feeling light-headed or short of breath.

Common side effects of pemetrexed may include:

  • tiredness, feeling short of breath, cough;

  • swelling or sores in mouth, sore throat;

  • fever, rash;

  • low blood cell count;

  • loss of appetite; or

  • nausea, vomiting, diarrhea, constipation.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Before taking this medicine

You should not be treated with pemetrexed if you are allergic to it.

Tell your doctor if you have ever had:

  • kidney disease; or

  • radiation treatment.

You may need to have a negative pregnancy test before starting this treatment.

Pemetrexed can harm an unborn baby or cause birth defects if the mother or the father is using pemetrexed.

  • If you are a woman, do not use pemetrexed if you are pregnant. Use effective birth control to prevent pregnancy while you are using this medicine and for at least 6 months after your last dose.

  • If you are a man, use effective birth control if your sex partner is able to get pregnant. Keep using birth control for at least 3 months after your last dose.

  • Tell your doctor right away if a pregnancy occurs while either the mother or the father is using pemetrexed.

This medicine may affect fertility (ability to have children) in men. However, it is important to use birth control to prevent pregnancy because pemetrexed can harm an unborn baby.

You should not breastfeed while you are using pemetrexed, and for at least 1 week after your last dose.

How is pemetrexed given?

Pemetrexed is given as an infusion into a vein. A healthcare provider will give you this injection.

Pemetrexed is usually given every 3 weeks. Your doctor will determine how many treatment cycles you should receive.

To prevent certain side effects of pemetrexed, you will need to take folic acid supplements and receive vitamin B12 injections (starting 7 days before your first dose of pemetrexed). Take only the amount of folic acid that your doctor has prescribed.

Your doctor may also prescribe steroid medication to reduce certain side effects of pemetrexed. Follow your doctor's dosing instructions very carefully.

Call your doctor if you are sick with vomiting or diarrhea, or if you are sweating more than usual. You can easily become dehydrated while taking pemetrexed. This can lead to very low blood pressure, a serious electrolyte imbalance, or kidney failure.

Pemetrexed can lower blood cells that help your body fight infections and help your blood to clot. Your blood will need to be tested often. Your cancer treatments may be delayed based on the results of these tests.

What happens if I miss a dose?

Call your doctor for instructions if you miss an appointment for your pemetrexed injection.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while receiving pemetrexed?

If you have kidney disease, avoid taking ibuprofen (Advil, Motrin) for 2 days before or 2 days after you are treated with pemetrexed.

Avoid being near people who are sick or have infections. Tell your doctor at once if you develop signs of infection.

Avoid activities that may increase your risk of bleeding or injury. Use extra care to prevent bleeding while shaving or brushing your teeth.

What other drugs will affect pemetrexed?

Pemetrexed can harm your kidneys, especially if you also use certain medicines for infections, cancer, osteoporosis, organ transplant rejection, bowel disorders, high blood pressure, or pain or arthritis (including Advil, Motrin, and Aleve).

Other drugs may affect pemetrexed, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Popular FAQ

Pemetrexed works in cancer by blocking certain enzymes involved in folate metabolism and DNA synthesis, which interferes with the process needed for a cell to divide and replicate. Continue reading

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.