Pemetrexed (Alimta)

Pemetrexed is a type of chemotherapy. It is also known as Alimta. You might have it as a treatment for:

  • pleural mesothelioma (cancer of the outer covering of the lungs)
  • non small cell lung cancer (NSCLC)

For NSCLC, you might have pemetrexed on its own or in combination with other cancer drugs such as cisplatin, carboplatin or pembrolizumab. 

How does pemetrexed work?

Pemetrexed is a type of drug known as an anti metabolite. It stops cancer cells making and repairing DNA so they can't grow and multiply.

How do you have pemetrexed?

You have pemetrexed as a drip into your bloodstream (intravenously).

You might have treatment through a long plastic tube that goes into a large vein in your chest. The tube stays in place throughout the course of treatment. This can be a:

  • central line
  • PICC line
  • portacath

If you don't have a central line

You might have treatment through a thin short tube (a cannula) that goes into a vein in your arm. You have a new cannula each time you have treatment.

How often do you have pemetrexed?

You usually have pemetrexed every 3 weeks. Each treatment takes about 10 minutes.

Pemetrexed blocks the action of folic acid in the body. To help reduce the side effects this can cause, you might have:

  • folic acid tablets for around 5 days before treatment and for 21 days (3 weeks) after treatment
  • a vitamin B12 injection in the week before you start treatment and then every 9 weeks

You may also take corticosteroids such as dexamethasone the day before treatment starts and for 3 to 5 days each time you have pemetrexed. This is to help lower the chance of getting any skin problems. 


You have blood tests before and during your treatment. They check your levels of blood cells and other substances in the blood. They also check how well your liver and kidneys are working.

What are the side effects of pemetrexed?

Side effects can vary from person to person. They also depend on what other treatments you're having. 

When to contact your team

Your doctor, nurse or pharmacist will go through the possible side effects. They will monitor you during treatment and check how you are at your appointments. Contact your advice line as soon as possible if:

  • you have severe side effects 

  • your side effects aren’t getting any better

  • your side effects are getting worse

Early treatment can help manage side effects better. 

Contact your advice line immediately if you have signs of infection, including a temperature above 37.5C or below 36C.

We haven't listed all the side effects here. Remember it is very unlikely that you will have all of these side effects. But you might have some of them at the same time.

Common side effects

These side effects happen in more than 10 in 100 people (more than 10%). You might have one or more of them. They include:

Risk of infection

Increased risk of getting an infection is due to a drop in white blood cells. Symptoms include a change in temperature, aching muscles, headaches, feeling cold and shivery and generally unwell. You might have other symptoms depending on where the infection is.

Infections can sometimes be life threatening. You should contact your advice line urgently if you think you have an infection. 

Breathlessness and looking pale

You might be breathless and look pale due to a drop in red blood cells. This is called anaemia.

Diarrhoea or constipation 

Tell your healthcare team if you have diarrhoea or constipation. They can give you medicine to help. 

Feeling or being sick 

Feeling or being sick is usually well controlled with anti sickness medicines. It might help to avoid fatty or fried foods, eat small meals and snacks and take regular sips of water. Relaxation techniques might also help.

It is important to take anti sickness medicines as prescribed even if you don’t feel sick. It is easier to prevent sickness rather than treat it once it has started.

Mouth sores and ulcers

Mouth sores and ulcers can be painful. It helps to keep your mouth and teeth clean, drink plenty of fluids and avoid acidic foods such as lemons. Chewing gum can help to keep your mouth moist. Tell your doctor or nurse if you have ulcers.

Loss of appetite 

You might lose your appetite for various reasons while having cancer treatment. Sickness, taste changes or tiredness can put you off food and drinks.

Fatigue (tiredness)

You might feel very tired and as though you lack energy.

Various things can help you to reduce tiredness and cope with it, for example exercise. Some research has shown that taking gentle exercise can give you more energy. It is important to balance exercise with resting.

Skin problems 

Skin problems include a skin rash, dry skin and itching. This usually goes back to normal when your treatment finishes. Your healthcare team can tell you what products you can use on your skin to help.

To reduce the skin rash your nurse might give you corticosteroids. You usually take them on the day before treatment, the day of treatment, and the day afterwards.

Numbness or tingling in fingers and toes

Numbness or tingling in fingers or toes is often temporary and can improve after you finish treatment. Tell your healthcare team if you're finding it difficult to walk or complete fiddly tasks such as doing up buttons. 

Kidney changes

To help prevent kidney damage, it is important to drink plenty of water. You might also have fluids into your vein before, during and after treatment. You have blood tests before your treatments to check how well your kidneys are working.

Sore throat (pharyngitis) 

You might get a sore, scratchy, dry throat as the tissues can become inflamed. 

Occasional side effects

These side effects happen in between 1 and 10 out of every 100 people (between 1 and 10%). You might have one or more of them. They include: 

  • an allergic reaction that can cause a skin rash, burning or a prickling sensation
  • bruising, nosebleeds or bleeding caused by a drop in platelets in your blood
  • hair loss or hair thinning
  • high temperature (fever)
  • loss of fluid (dehydration) that can make you feel thirsty and have dark yellow and strong smelling urine
  • pain in your chest and tummy (abdomen)
  • inflammation of the eyes and watery eyes (conjunctivitis), dry eyes, swollen eyelids, excess tears
  • taste changes that can make you go off certain foods
  • indigestion symptoms including heartburn, bloating and burping
  • liver changes that are usually mild and unlikely to cause symptoms
  • dizziness
  • changes in the way your heart works - you may have changes to your heart beat, feel dizzy, have shortness of breath or chest pain - contact your advice line if you have this. Rarely your heart might stop beating (heart attack)
  • a build up of fluid in your body (oedema)

Rare side effects

These side effects happen in fewer than 1 in 100 people (fewer than 1%). You might have one or more of them. They include: 

  • inflammation of the lining of the bowel (colitis) which can cause bleeding when you have pemetrexed with another drug called cisplatin
  • scarring on the air sacs of your lungs which can cause a dry cough, chest pain and shortness of breath
  • blood clots that can be life threatening; signs are pain, redness and swelling where the clot is. Feeling breathless can be a sign of a blood clot in the lung. Contact your advice line or doctor straight away if you have any of these symptoms
  • a swollen liver which might cause pain in the tummy, nausea or feeling full. You will have tests to check your liver function
  • pain, coldness and paleness in your hands and feet
  • a severe skin reaction that may start as tender red patches which leads to peeling or blistering of the skin. You might also feel feverish and your eyes may be more sensitive to light. This is serious and could be life threatening
  • reduced blood flow to your limbs
  • a stroke or a bleed in the brain
  • lung changes such as shortness of breath if you are having or had radiotherapy to the lungs (radiation pneumonitis) or tightness of the chest and wheezing
  • bleeding from the back passage (rectum)
  • bleeding in the bowel or stomach
  • sore, inflamed skin in the food pipe (oesophagus)

Coping with side effects

We have more information about side effects and tips on how to cope with them.

What else do I need to know

Other medicines, foods and drinks

Cancer drugs can interact with some other medicines and herbal products. Tell your doctor or pharmacist about any medicines you are taking. This includes vitamins, herbal supplements and over the counter remedies.

Ibuprofen (Neurofen)

You should avoid taking ibuprofen from 5 days before and up until 2 days after pemetrexed. Ibuprofen can make the pemetrexed side effects worse.  


This drug contains sodium (salt). You might need to take account of this if you are on a controlled sodium diet. Tell your doctor if you are on a low salt diet. 

Pregnancy and contraception

This treatment may harm a baby developing in the womb. It is important not to become pregnant or get someone pregnant while you're having treatment and for at least 6 months afterwards.

Talk to your doctor or nurse about effective contraception before starting treatment. Let them know straight away if you or your partner become pregnant while having treatment. 

Loss of fertility

You may not be able to become pregnant or get someone pregnant after treatment with this drug. Talk to your doctor before starting treatment if you think you may want to have a baby in the future.

Men might be able to store sperm before starting treatment. And women might be able to store eggs or ovarian tissue. But these services are not available in every hospital, so you would need to ask your doctor about this.    


Don’t breastfeed during this treatment because the drug may come through into your breast milk.

Treatment for other conditions 

If you are having tests or treatment for anything else, always mention your cancer treatment. For example, if you are visiting your dentist.


Don’t have immunisations with live vaccines while you’re having treatment and for up to 12 months afterwards. The length of time depends on the treatment you are having. Ask your doctor or pharmacist how long you should avoid live vaccinations.

In the UK, live vaccines include rubella, mumps, measles, BCG, yellow fever and one of the shingles vaccines called Zostavax.

You can have:

  • other vaccines, but they might not give you as much protection as usual
  • the flu vaccine (as an injection)
  • the coronavirus (COVID-19) vaccine - talk to your doctor or pharmacist about the best time to have it in relation to your cancer treatment

Members of your household who are aged 5 years or over are also able to have the COVID-19 vaccine. This is to help lower your risk of getting COVID-19 while having cancer treatment and until your immune system Open a glossary item recovers from treatment.

Contact with others who have had immunisations - You can be in contact with other people who have had live vaccines as injections. Avoid close contact with people who have recently had live vaccines taken by mouth (oral vaccines) such as the oral typhoid vaccine. Sometimes people who have had the live shingles vaccine can get a shingles type rash. If this happens they should keep the area covered.

If your immune system is severely weakened, you should avoid contact with children who have had the flu vaccine as a nasal spray as this is a live vaccine. This is for 2 weeks following their vaccination.

Babies have the live rotavirus vaccine. The virus is in the baby’s poo for about 2 weeks and could make you ill if your immunity is low. Get someone else to change their nappies during this time if you can. If this isn't possible, wash your hands well after changing their nappy.

More information about this treatment

For further information about this treatment and possible side effects go to the electronic Medicines Compendium (eMC) website. You can find the patient information leaflet on this website.

You can report any side effect you have to the Medicines Health and Regulatory Authority (MHRA) as part of their Yellow Card Scheme.

  • Electronic Medicines Compendium
    Accessed June 2022

  • Immunisation against infectious disease: Chapter 6: General contraindications to vaccination
    Public Health England
    First published: March 2013 and regularly updated on the Gov.UK website

  • Consent forms for SACT (Systemic Anti-Cancer Therapy)
    Cancer Research UK, Last accessed June 2022

  • Pemetrexed for the maintenance treatment of non-small-cell lung cancer
    The National Institute for Health and Care Excellence (NICE), June 2010

  • Pembrolizumab with pemetrexed and platinum chemotherapy for untreated, metastatic, non-squamous non-small-cell lung cancer
    The National Institute for Health and Care Excellence (NICE), January 2019

Last reviewed: 
29 Jun 2022
Next review due: 
29 Jun 2025

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