1. What is neratinib?
2. Who might be offered neratinib?
3. When is it given?
4. How does neratinib work?
5. How is neratinib taken?
6. Common side effects of neratinib
7. Less common side effects
8. Medicines and food to avoid when taking neratinib
9. Blood clots
10. Sex and contraception
11. Breastfeeding and neratinib
12. Travel and vaccinations
13. Further support

1. What is neratinib?

Neratinib is a targeted (biological) therapy drug that blocks the growth and spread of breast cancer. 

Neratinib is the drug’s non-branded name. Its brand name is Nerlynx.

2. Who might be offered neratinib?

Neratinib may be offered to people who have primary breast cancer that is both:

  • Hormone receptor positive (breast cancer that’s stimulated to grow by the hormones oestrogen or progesterone)
  • HER2 positive (breast cancer that has a higher than normal level of the HER2 protein)

3. When is it given?

Neratinib is given after you have surgery and have completed treatment with trastuzumab. Neratinib should be started within a year of finishing trastuzumab.

If you have pertuzumab after surgery, you will not be offered neratinib. However, you may be offered neratinib if you have pertuzumab before surgery.

4. How does neratinib work? 

Targeted (biological) therapies block the growth and spread of cancer. They target and interfere with processes in the cells that help cancer grow.

Some breast cancer cells have a higher than normal level of a protein called HER2 on their surface, which stimulates them to grow. This is called HER2 positive breast cancer. 

Neratinib blocks HER2 and two other proteins that also stimulate breast cancer cells to grow.

There are various tests to measure HER2 levels, which are done on breast tissue removed during a biopsy or surgery. 

If your cancer is found to be HER2 negative, then neratinib will not be of benefit to you.

5. How is neratinib taken?

Neratinib is taken as a tablet.

The recommended dose is 240 milligrams (six 40 milligram tablets) taken once a day. 

The tablets should be taken with food, preferably in the morning. 

What happens if I miss a dose?

If you miss a dose of neratinib, do not take an extra dose to make up for the one you missed. Take the usual dose the following day.

How long will I take neratinib for?

You will take neratinib for a year.

6. Common side effects of neratinib

Like any drug, neratinib can cause side effects. Everyone reacts differently to drugs and some people have more side effects than others. 

Side effects can usually be controlled and those described here will not affect everyone.

If you’re concerned about any side effects, regardless of whether they’re listed here, talk to your chemotherapy nurse or cancer specialist (oncologist).


Diarrhoea is a very common side effect of neratinib, and it can be severe. This may cause dehydration. 

You’ll be prescribed drugs to take with neratinib to help prevent diarrhoea. Start taking these as soon as you begin to take neratinib. Your treatment team will tell you how long to take these drugs for and when to stop taking them. 

Contact your treatment team if you have four or more episodes of diarrhoea within a 24-hour period. 

Drink plenty of fluids to avoid getting dehydrated.

Sometimes your treatment team may recommend reducing the dose of neratinib or stopping altogether if diarrhoea is very severe. 

Nausea and vomiting

You may experience nausea (feeling sick) and vomiting (being sick). 

Although not usually needed, anti-sickness drugs can be prescribed to help with this.

Fatigue (extreme tiredness)

It’s common to feel extremely tired during your treatment. There are different ways of coping with and managing fatigue

You can speak to your treatment team or contact Breast Cancer Now for more information and support.

Stomach pain

You may have some pain in your tummy or feel bloated. Tell your treatment team if you get this.


This can be uncomfortable but using a moisturiser and a high-factor sunscreen may help. 

Your treatment team may suggest drugs such as antihistamines to reduce any itching.

Loss of appetite

You may not feel like eating, especially if you’re feeling sick. 

It might help to eat small meals regularly and drink plenty of liquids. 

Some people lose weight while taking neratinib.

Sore mouth

Your mouth may become sore or dry and you may get ulcers. 

You may be given mouthwash to reduce soreness of the mouth and gums and to try to stop mouth ulcers developing. Good mouth hygiene is very important during treatment.

Muscle spasms

You may have some muscle spasms (painful twitching of the muscles) while taking neratinib. 

Drinking plenty of fluids and taking regular exercise may help. Your treatment team may also suggest a blood test.

7. Less common side effects

Liver changes

Neratinib can affect how the liver works. 

You’ll have blood tests to check your liver function while you’re having treatment.

Sometimes neratinib may be delayed or the dose reduced if tests show any problems with your liver.

Contact your treatment team straight away if you have any of the following symptoms:

  • Yellowing of your skin or the whites of your eyes (jaundice)
  • Pain on your right side under the ribs
  • Bleeding or bruising more easily than normal
  • Feeling more tired
  • Passing dark brown urine

Kidney problems

Neratinib can cause changes to the way the kidneys work. You’ll have regular blood tests during your treatment to check this. 

Urine infections

If you have pain when passing urine, need the toilet more often than usual and only pass small amounts, tell your treatment team. You may have an infection and need antibiotics.

Nose bleeds

Some people have nose bleeds while taking neratinib. Tell your treatment team if this happens.

Dry or cracked skin

You may have dry skin including mild scaling, roughness, feelings of tightness or itching.

It may help to:

  • Use a moisturiser regularly and avoid perfumed products
  • Protect your hands when doing household or outdoor chores
  • Rinse and dry your hands carefully, particularly after contact with cleaning products
  • Pat your skin dry with a soft towel, rather than rubbing vigorously
  • Take care when shaving
  • Wear cotton clothes where possible next to the skin and wash clothes in mild detergent

Nail changes

Some people have nail problems, such as nail splitting or colour change, while taking neratinib.

8. Medicines and food to avoid when taking neratinib

Some drugs should not be taken with neratinib. 

Tell your treatment team about any prescribed or over-the-counter medicines you’re taking. 

If a healthcare professional, such as your GP or dentist, prescribes a new drug, tell them you’re taking neratinib.

Neratinib must not be taken with anything containing St John’s Wort. Ask your treatment team before taking any herbal medicines or supplements.

Avoid eating grapefruit or drinking grapefruit juice while taking neratinib. Grapefruit may interact with neratinib and affect how the medicine works.

9. Blood clots

People with breast cancer have a higher risk of blood clots. Their risk is higher because of the cancer itself and some treatments for breast cancer.

Blood clots can be harmful but are treatable so it’s important to report symptoms as soon as possible. If you develop a blood clot during treatment, your treatment may be put on hold until the clot has been treated.

If you have any of the following symptoms contact your local A&E department, GP or treatment team straight away:

  • Pain, redness/discolouration, heat and swelling of the calf, leg or thigh
  • Swelling, redness or tenderness where a central line is inserted to give chemotherapy, for example in the arm, chest area or up into the neck
  • Shortness of breath
  • Tightness in the chest
  • Unexplained cough (or coughing up blood)

Find out more about blood clots

10. Sex and contraception

Taking neratinib while pregnant may be harmful to a developing baby. Some women can still become pregnant even if their periods are irregular or have stopped.

Women should use an effective barrier contraception during treatment and continue for one month after completing their treatment.

It is not known if taking neratinib affects fertility.

11. Breastfeeding and neratinib 

It’s not known if neratinib passes to a baby through breast milk. Speak to your treatment team if you plan to breastfeed. 

12. Travel and vaccinations 

If you’re planning a holiday or need to travel overseas, check with your treatment team first. 

You should not have any live vaccines while you’re taking neratinib. 

Live vaccines include measles, rubella (German measles), polio, BCG (tuberculosis), shingles and yellow fever.

Live vaccines contain a small amount of live virus or bacteria. These could be harmful and cause infections.

If someone you have close contact with needs to have a live vaccine speak to your treatment team or GP. They can advise what precautions you may need to take depending on the vaccination.

Flu vaccination

Anyone at risk of a weakened immune system, and therefore more prone to infection, should have the flu vaccine. This includes people due to have, or already having, treatment for breast cancer.

The flu vaccine is not a live vaccine so doesn’t contain any active viruses. Talk to your treatment team about the best time to have your flu jab.

13. Further support

Being diagnosed with breast cancer can make you feel lonely and isolated.

Many people find it helps to talk to someone who has been through the same experience as them. You can ask questions and chat to other people on Breast Cancer Now’s online Forum

For further information and support or to talk things through, you can speak to one of our experts by calling our free Helpline on 0808 800 6000.

Last reviewed: March 2020
Next planned review begins 2022

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