Pemetrexed (Alimta) | Cancer Research UK
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What pemetrexed is

Pemetrexed is a chemotherapy drug used to treat non small cell lung cancer and pleural mesothelioma. Pleural mesothelioma is a cancer which affects the covering layer of the lungs. 

Pemetrexed is also known by its brand name Alimta. It is one of a group of drugs known as anti metabolites. These stop cells making and repairing the DNA that they need to grow and multiply. 

Pemetrexed is used to treat mesothelioma in combination with another chemotherapy drug called cisplatin. 

If you have pemetrexed as a treatment for non small cell lung cancer you may have it on its own or in combination with cisplatin.


How you have pemetrexed

You have pemetrexed into your bloodstream (intravenously). You can have it through a thin, short tube (a cannula) put into a vein in your arm each time you have treatment. Or you may have it through a central line, a portacath, or a PICC line. These are long, plastic tubes that give the drugs directly into a large vein in your chest. You have the tube put in before or during your course of treatment and it stays in place as long as you need it.

You can read our information about having chemotherapy into a vein.

Each pemetrexed treatment usually takes about 10 minutes and you usually have it every 3 weeks. The number of treatments you have depends on your treatment plan. Your treatment plan will depend on which cancer you have. 

Pemetrexed is a type of drug known as an anti folate. It blocks the action of folic acid in the body. To help reduce the side effects this causes, you need to

  • Take folic acid tablets – starting 5 days before you begin treatment, and continuing throughout treatment and for 3 weeks after treatment has finished
  • Have vitamin B12 injections – one injection in the week before you start treatment and then one before every 3rd treatment cycle

Tests during treatment

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


About side effects

We've listed the side effects associated with pemetrexed below. You can use the links to find out more about each side effect. Where there is no link, please go to our cancer drug side effects section or use the search box at the top of the page.

You may have a few side effects. They may be mild or more severe. A side effect may get better or worse through your course of treatment. Or more side effects may develop as the course goes on. This depends on

  • How many times you've had the drug before
  • Your general health
  • The amount of the drug you have (the dose)

The side effects may be different if you are having pemetrexed with other drugs.

Tell your doctor or nurse straight away if any of the side effects get severe.


Common side effects

More than 10 in every 100 people have one or more of the side effects listed below.

  • An increased risk of getting an infection from a drop in white blood cells – it is harder to fight infections and you can become very ill. You may have headaches, aching muscles, a cough, a sore throat, pain passing urine, or you may feel cold and shivery. If you have a severe infection this can be life threatening. Contact your treatment centre straight away if you have any of these effects or if your temperature goes above 38°C
  • Tiredness and breathlessness due to a drop in red blood cells (anaemia) – you may need a blood transfusion
  • Bruising more easily due to a drop in platelets – you may have nosebleeds, or bleeding gums after brushing your teeth. Or you may have lots of tiny red spots or bruises on your arms or legs (known as petechiae)
  • Tiredness and weakness (fatigue) affects about 1 in 3 people (34%) during and after treatment – most people find their energy levels are back to normal within 6 months to a year
  • Feeling or being sick happens in almost 1 out of every 2 people (47%) but is usually well controlled with anti sickness medicines
  • Loss of appetite happens in about 1 in 5 people (20%)
  • A skin rash happens in nearly 1 in 6 people (16%) – you may have some itching and your skin may become sore. To reduce the skin rash your nurse will give you steroids. You need to take them on the day before treatment, the day of treatment, and the day afterwards
  • Diarrhoea occurs in just over 1 out of 7 people (13%) – drink plenty of fluids and tell your doctor or nurse if diarrhoea becomes severe,. Also tell them if it continues for more than 3 days
  • A sore mouth and throat affects almost a quarter of people (23%)
  • Women may stop having periods (amenorrhoea) but this may be temporary
  • Loss of fertility – you may not be able to become pregnant or father a child after this treatment. Talk to your doctor before starting treatment if you think you may want to have a baby in the future. Men may be able to store sperm before starting treatment
  • Hair loss or thinning that is temporary – your hair will grow back when the treatment ends
  • Constipation – drink plenty of fluids and tell your doctor or nurse if it continues for more than 3 days
  • Kidney changes that are unlikely to cause symptoms – your kidneys will almost certainly go back to normal when treatment ends
  • Numbness or tingling in the fingers and toes – you may have trouble with fiddly tasks such as doing up buttons. This can start a few days or weeks after treatment and usually goes away within a few months of the treatment ending


Occasional side effects

Between 1 and 10 in every 100 people have one or more of these effects.

  • Liver changes that are very mild and unlikely to cause symptoms – the liver will almost certainly go back to normal when treatment ends
  • A high temperature (fever) – taking paracetamol every 6 to 8 hours can help until your temperature goes down
  • An allergic reaction to the drug – let your nurse know straight away if you have skin flushing, feel hot or have swelling of the lips, face or tongue
  • Itching
  • Muscle weakness
  • Weight loss
  • Sore, red eyes (conjunctivitis) or watery eyes – your nurse can give you eye drops to help
  • Taste changes
  • Indigestion
  • Tummy (abdominal) pain

Rare side effects

Fewer than 1 in 100 people have these effects.

  • A faster heart rate
  • Inflammation of the bowel lining that may cause bleeding from the back passage. Let your doctor or nurse know if you have this
  • Scarring of the air sacs in the lungs – tell your doctor or nurse if you develop a dry cough, chest pain, or shortness of breath. You will have lung tests before you start your course of treatment and several times during the months of your treatment
  • Swelling of parts of the body, caused by fluid build up
  • Pain, coldness and paleness of hands and feet
  • Blood clots in the lungs – tell your doctor or nurse straight away if you have sudden severe chest pain, shortness of breath or cough up blood

Important points to remember

Talk to your doctor, pharmacist or nurse about all your side effects so they can help you manage them. They can give you advice or reassure you. Your nurse will give you a contact number to ring if you have any questions or problems. If in doubt, call them.

Other medicines

Tell your doctor about any other medicines you are taking, including vitamins, herbal supplements and over the counter remedies. Some drugs can react together.

Pregnancy and contraception

This drug may harm a baby developing in the womb. It is important not to become pregnant or father a child while you are having treatment and for a few months afterwards. Talk to your doctor or nurse about effective contraception before starting treatment. You need to use reliable contraception while you are having treatment. Men need to continue using contraception for 6 months after the end of treatment.


Do not breastfeed during this treatment because the drug may come through in the breast milk.


Immunisations and chemotherapy

You should not have immunisations with live vaccines while you are having chemotherapy or for at least 6 months afterwards. In the UK, these include rubella, mumps, measles (usually given together as MMR), BCG, yellow fever and Zostavax (shingles vaccine).

You can have other vaccines, but they may not give you as much protection as usual until your immune system has fully recovered from your chemotherapy. It is safe to have the flu vaccine.

It is safe for you to be in contact with other people who've had live vaccines as injections. There can be problems with vaccines you take by mouth (oral vaccines), but not many people in the UK have these now. So there is usually no problem in being with any baby or child who has recently had any vaccination in the UK. You might need to make sure that you aren't in contact with anyone who has had oral polio, cholera or typhoid vaccination recently, particularly if you live abroad.


Related information


More information about pemetrexed

This page does not list all the very rare side effects of this treatment that are very unlikely to affect you. For further information look at the Electronic Medicines Compendium website at

If you have a side effect not mentioned here that you think may be due to this treatment you can report it to the Medicines Health and Regulatory Authority (MHRA) at

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Updated: 19 June 2015