Neratinib (Nerlynx)

Neratinib is a type of targeted cancer drug. It is also known as Nerlynx. It is a treatment for early stage breast cancer that is hormone receptor positive and human epidermal growth factor receptor 2 positive (HER2 positive) Open a glossary item.

You have tests on your breast cancer cells to check for these.

How neratinib works

Neratinib is a targeted cancer drug that works on a protein called human epidermal growth factor receptor 2 (HER2). HER2 proteins make cells divide and grow. Some cancers have large amounts of HER2 proteins which can cause cancer cells to divide and grow faster.

Neratinib works by locking onto the HER2 on the cancer cells. So it stops the cells from growing.

How you have neratinib

You have neratinib as tablets. You take the tablets with food and swallow them whole with water.

Taking your tablets

You must take tablets according to the instructions your doctor or pharmacist gives you.

Speak to your pharmacist if you have problems swallowing the tablets.

Whether you have a full or an empty stomach can affect how much of a drug gets into your bloodstream.

You should take the right dose, no more or less.

Talk to your healthcare team before you stop taking a cancer drug or if you miss a dose.

When you have neratinib

You take neratinib once a day, usually in the morning. You take them every day for a year.


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.

Side effects

How often and how severe the side effects are 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:


Contact your advice line if you have diarrhoea, such as if you've had 4 or more loose watery poos (stools) in 24 hours. Or if you can't drink to replace the lost fluid. Or if it carries on for more than 3 days.

You will have anti diarrhoea medicine to take home to try to prevent this problem. Your healthcare team will explain how and when you should take them.

Eat less fibre, avoid raw fruits, fruit juice, cereals and vegetables, and drink plenty to replace the fluid lost.

Feeling or being sick

Feeling or being sick is usually well controlled with anti sickness medicines. Avoiding fatty or fried foods, eating small meals and snacks, drinking plenty of water, and relaxation techniques can all 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 treating it once it has started.

Tiredness and weakness

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 rash

A rash can also be itchy. Less commonly your skin might get dry, crack and split. Tell your doctor or nurse if you have a skin rash. They can prescribe medicine to stop the itching and soothe your skin.

Loss of appetite

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

Tummy (abdominal) pain

Tell your doctor or nurse if you have this. They can check for the cause of the pain and give you medicine to help. 

Sore mouth

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 the mouth moist. Tell your doctor or nurse if you have ulcers.

Muscle spasms

Let your doctor or nurse know if you have muscle spasms during or after having treatment. 

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:

  • infection of your water works (urinary tract infection) – you might have stinging or burning sensation when you wee, you might go very often or need to go very urgently
  • lack of fluid in your body (dehydration)
  • nose bleeds
  • bloating of your tummy
  • dry mouth
  • heartburn or indigestion
  • liver changes usually picked up on blood tests - you have regular blood tests to check this
  • nail changes - they may break easily, the colour might change or you might develop an infection
  • weight loss
  • high levels of a waste product (creatinine) in your blood – you have regular blood tests to check for this

Rare side effects

This side effect happens in fewer than 1 in 100 people (less than 1%). 

  • Your kidneys stop working properly (you have regular blood tests to check for this) – symptoms might include feeling or being sick, weeing less than usual, blood in your wee, tiredness, confusion, fluid build up in your ankles, feet and hands

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.

Grapefruit or pomegranate

You should not eat grapefruit or pomegranate when you are taking this drug. And you should not drink grapefruit or pomegranate juice, or any supplements that might contain them. This is because they may increase the side effects.

Loss of fertility

It is not known whether this treatment affects fertility in people. Talk to your doctor before starting treatment if you think you may want to have a baby in the future.

Contraception and pregnancy

It is unknown whether treatment may or may not harm a baby developing in the womb. It is important not to become pregnant or father a child while you are having treatment.

Women taking neratinib should use a hormonal contraceptive and a barrier method of contraception during treatment for at least 1 month after finishing treatment.

Men should use a barrier method of contraception, such as a condom during treatment and for at least 3 months after finishing treatment.

Talk to your healthcare team about contraception you can use during treatment.


It is not known whether this drug comes through into the breast milk. Doctors usually advise that you don’t breastfeed during this treatment.

Treatment for other conditions

Always tell other doctors, nurses, pharmacists or dentists that you’re having this treatment. For example, if you need treatment for anything else, including teeth problems.


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 go to the electronic Medicines Compendium (eMC) website.

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

This page is due for review. We will update this as soon as possible.

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