Pemetrexed (Alimta®)

Author: Christina Bach, LCSW, MBE, OSW-C
Content Contributor: Allyson Van Horn, MPH
Last Reviewed: July 9, 2026

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Pronounce: pem-e-TREX-ed

Classification: Antifolate Antineoplastic Agent

About Pemetrexed (Alimta®)

This medication works by blocking three enzymes that cells need to replicate. These enzymes, needed for folate-dependent metabolic processes, are required for DNA replication. By blocking DNA production, cell growth and division are stopped, causing cancer to slow or stop growing. Since cancer cells, in general, divide faster and with less error-correcting than healthy cells, cancer cells are more sensitive to this damage.

How to Take This Medication

This medication is given by intravenous (IV, into a vein) infusion. The dose is based on your height and weight. A steroid medication is often given before pemetrexed to decrease skin rash. A folic acid supplement and an injection of B12 may be given along with pemetrexed. These vitamin supplements should decrease the side effects you may have. Speak with your provider about specific dosing of steroids, folic acid, and B12 and the timing of these medications.

Let your provider know all medications, vitamins, and supplements you are taking as some can affect how this medication works. Tell your provider if you take any form of NSAID (non-steroidal anti-inflammatory drug), such as aspirin or ibuprofen because, taken with this medication, it can cause kidney problems.

Possible Side Effects

These are some of the most common or most serious side effects of this medication. Talk with your provider about the side effects you are having and how they can be managed.

Nausea and/or Vomiting

Talk to your providers if you have nausea and/or vomiting. They can prescribe medications to help you. Making changes to your diet can also help. Avoid things that make your symptoms worse, like heavy or greasy/fatty foods and spicy or acidic foods, like tomatoes, lemons, and oranges. Try saltines or ginger ale to help your symptoms.  

Call your providers if you cannot keep fluids down for more than 12 hours or if you feel lightheaded or dizzy.

Decrease in Appetite or Taste Changes

Nutrition is an important part of your care. Cancer treatment can affect your appetite and make it hard to eat. Ask your provider about nutrition counseling services. Some tips you can follow are:

  • Try to eat five or six small meals or snacks during the day, instead of 3 larger meals.
  • Nutritional supplements may help if you are not eating enough.
  • You may have a metallic taste or find that food has no taste. You may dislike foods or beverages that you liked before cancer treatment. These symptoms can last for months or longer after treatment ends.
  • Avoid any food that you think smells or tastes bad. If red meat is a problem, eat chicken, turkey, eggs, dairy products, and fish without a strong smell. Sometimes cold food has less of an odor.
  • Add extra flavor to meat or fish by marinating it in sweet juices, sweet and sour sauce, or dressing.
  • Use seasonings like basil, oregano, or rosemary to add flavor.

Fatigue

Fatigue can cause exhaustion, feeling worn out and that your body is "heavy" and hard to move, or being unable to focus. It is common when you have cancer, and it is not the same as feeling tired. You may need to adjust your schedule to manage fatigue. Plan times to rest during the day and save your energy for more important activities. Exercise can help lessen fatigue. Talk to your providers about ways to deal with this side effect.

Reproductive Concerns

There is a higher risk of health problems for your baby if you are pregnant, become pregnant, or get someone pregnant while on this medication. To lower the risk of birth defects, you should use birth control (contraception) to avoid pregnancy. Talk with your provider about what kind of birth control is safest for you and your partner.

If you can become pregnant, you will need to use effective birth control during treatment and for 6 months after the last dose of this medication, even if your menstrual cycle has stopped or changed. If you can get someone pregnant, you will need to use effective birth control during treatment and for 3 months after the last dose of this medication, even if you believe you are not producing sperm. You should not breastfeed during treatment and for 1 week after the last dose of this medication.

Important but Less Common Side Effects

Low White Blood Cell Count (Leukopenia or Neutropenia)

White blood cells (WBC) help your body fight infection. While you are having treatment for cancer, your WBC count can drop, putting you at a higher risk of an infection. Tell your provider right away if you have a fever (temperature greater than 100.4°F or 38°C), sore throat or cold, shortness of breath, cough, burning with urination, or a sore that doesn't heal.

Tips for preventing infection:

  • Hand washing: both yours and your visitors is the best way to prevent the spread of infection.
  • Avoid large crowds and people who are sick (those who have a cold, fever, or cough, or live with someone with these symptoms).
  • When working outside, wear clothes that protect you, like long pants and gloves.
  • Do not handle pet waste.
  • Keep all cuts and scratches clean.
  • Shower or bathe daily. 
  • Brush your teeth at least twice a day.
  • Do not cut cuticles or ingrown nails. You may wear nail polish, but not fake nails.
  • Ask your providers before scheduling dental appointments or procedures.
  • Ask your providers before you or someone you live with has any vaccines

Low Platelet Count (Thrombocytopenia)

Platelets are blood cells that help your blood clot. Thrombocytopenia is when your platelet count is lower than normal, and you are at a higher risk of bleeding. Tell your providers if you have any bruising or bleeding, including nose bleeds, bleeding gums, or blood in your urine or stool. If your count gets too low, you may receive platelets from a donor. 

  • Do not use a razor (an electric razor is fine).
  • Do not do activities that can cause injury or bleeding.
  • Talk to your provider before taking any non-steroidal, anti-inflammatory medications (NSAIDs) like Motrin/Advil (ibuprofen), Aleve (naproxen), Celebrex (celecoxib), and others. These can raise the risk of bleeding. 
  • Use a soft-bristle toothbrush to brush your teeth. Ask your provider about flossing or using toothpicks. 

Low Red Blood Cell Count (Anemia)

Anemia is when your red blood cell count is lower than normal. Red blood cells carry oxygen to the tissues in your body. When your red cell count is low, you may feel tired or weak. Tell your providers if you have shortness of breath, trouble breathing, or pain in your chest. If your count gets too low, you may receive a blood transfusion.

Kidney Problems

This medication can cause kidney problems, like an increased creatinine level. Your provider may monitor for kidney problems with blood tests. Symptoms may be:

  • Less urine output than normal.
  • Blood in the urine.
  • Swelling in the ankles.
  • Loss of appetite.

Tell your provider if you have any of these symptoms.

Rash

Some people may get a rash, scaly skin, or red, itchy bumps from this medication. Tell your provider if you notice any of these changes in your skin, since it could be a reaction. Your provider may suggest:

  • Using an alcohol-free moisturizer on your skin and lips, and do not use moisturizers with perfumes or scents. 
  • Keep the area clean to avoid infection, especially if it cracks or bleeds.
  • Using a topical medication (applied to the skin) if the itching bothers you.

Be sure to talk with your provider about how to care for your skin.

Radiation Recall

Radiation recall is when a medication causes a rash that looks like sunburn in an area where you had radiation treatment.

  • Redness.
  • Swelling.
  • Soreness.
  • Peeling skin.

You may be told to put a topical steroid cream on your skin, or you may need to wait to have your next scheduled dose of chemotherapy. Tell your provider if you notice any of these symptoms.

Pneumonitis

Pneumonitis is inflammation of the lungs. Tell your provider right away if you get any new or worsening symptoms, like:

  • Shortness of breath.
  • Trouble breathing.
  • A cough.
  • Fever.