What is osimertinib (Tagrisso®)?

Osimertinib (Tagrisso®) is used to treat non-small cell lung cancer that has begun to spread. It is used if tests on a sample of the tumour show the cancer cells have a change (mutation) in a gene called EGFR.

It is best to read this information with our general information about the type of cancer, you have.

Osimertinib is a type of targeted therapy drug called a cancer growth inhibitor.

Your doctor will talk to you about this treatment and its possible side effects before you agree (consent) to have treatment.

How osimertinib is given

During treatment you will see a cancer doctor, a cancer nurse or specialist nurse, and a specialist pharmacist. This is who we mean when we mention doctor, nurse or pharmacist in this information.

Osimertinib is given as tablets. This means you can take it at home.

Osimertinib can reduce the number of blood cells in your blood and may affect how your liver works. This is usually mild and is unlikely to affect your treatment. You may have regular blood tests to check for any changes.

Your nurse, pharmacist or doctor will discuss your treatment plan with you. Do not stop taking osimertinib without your doctor’s advice.

Taking osimertinib tablets

You take osimertinib once a day. Your doctor, nurse or pharmacist will tell you how many tablets to take. Always take them exactly as you are told to. This is important to make sure they work as well as possible for you.

Try to take your tablets at the same time each day. Swallow them whole with water. Do not chew, break or crush them.

If you cannot swallow the tablets, you can dissolve them in a small amount of water. Do not crush the tablets. Drop them into 50 ml of water and stir until they dissolve. Drink them straight away. Half fill the glass again with water and drink this too.

If you forget to take your tablets, do not take a double dose. If there is more than 12 hours until your next dose, take your tablets as soon as you remember.

If there is less than 12 hours until your next dose, do not take any tablets. Take your next dose at the usual time and let your doctor or nurse know.

Other things to remember about your tablets:

  • Keep them in the original package and at room temperature, away from heat and direct sunlight.
  • Keep them safe and out of sight and reach of children.
  • If your treatment is stopped return any unused tablets to the pharmacist.

About side effects

We explain the most common side effects of this treatment here. We also include some less common side effects.

You may get some of the side effects we mention, but you are unlikely to get all of them. If you are also having treatment with other cancer drugs, you may have some side effects that we have not listed here. Always tell your doctor, nurse or pharmacist about any side effects you have.

Your doctor can give you drugs to help control some side effects. It is important to take them exactly as your nurse or pharmacist explains. This means they will be more likely to work for you. Your nurse will give you advice about managing your side effects. After your treatment is over, most side effects start to improve.

Serious and life-threatening side effects

Some cancer treatments can cause severe side effects. Rarely, these may be life-threatening. Your cancer doctor or nurse can explain the risk of these side effects to you.

Contact the hospital

Your nurse will give you telephone numbers for the hospital. If you feel unwell or need advice, you can call them at any time of the day or night. Save these numbers in your phone or keep them somewhere safe.

More information

We cannot list every side effect for this treatment. There are some rare side effects that are not listed. You can visit the electronic Medicines Compendium (eMC) for more detailed information.

Common side effects


Osimertinib can cause diarrhoea but this is usually mild. If you have diarrhoea, contact the hospital for advice. Your nurse or doctor may give you anti-diarrhoea drugs to take at home.

Try to drink at least 2 litres (3½ pints) of fluids every day. It may help to avoid:

  • alcohol
  • caffeine
  • milk products
  • high-fat foods
  • high-fibre food.

Skin changes

This treatment can cause a rash. Usually this is mild. Sometimes this can be itchy. Tell your doctor or nurse if you have any skin changes. They can give you advice, creams and drugs to help.

Very rarely, a much more serious skin condition can develop. You may have a skin rash which then blisters, and your skin can peel. You may also feel unwell with flu-like symptoms such as a high temperature and joint pain. If you have any of these symptoms, contact your doctor or hospital immediately.

Nail changes

You may notice changes to your nails. They may become brittle and break easily. Wear gloves when washing dishes or using detergents to help protect your hands and nails. Dry your hands carefully after washing. If the area around your nails becomes red, hot or swollen, tell your doctor straight away.

Sore mouth and throat

This treatment may cause a sore mouth and throat. You may also get mouth ulcers. This can make you more likely to get a mouth or throat infection. Use a soft toothbrush to clean your teeth or dentures in the morning, at night and after meals.

If your mouth or throat is sore:

  • tell your nurse or doctor – they can give you a mouthwash or medicines to help
  • try to drink plenty of fluids
  • avoid alcohol, tobacco, and foods that irritate your mouth and throat.

Sucking ice chips may sometimes help relieve mouth or throat pain. But if you are having radiotherapy to the head or neck, do not suck on ice. It can cause damage.

Less common side effects

Effects on the lungs

Rarely, this treatment can cause unexpected changes to the lungs. Usually this is mild. Sometimes it can be serious or may need treatment. Always tell your doctor if you develop:

  • a cough
  • wheezing
  • a fever (high temperature)
  • breathlessness.

You should also tell them if any existing breathing problems get worse.

Effects on the eyes

Osimertinib may affect your eyes or eyesight. Tell your doctor or nurse if your

  • eyes are sore, red, watery or feel sensitive to light
  • eyesight is blurry.

They may arrange for you to see an eye doctor (ophthalmologist) for more advice.. Your doctor may tell you to stop taking osimertinib for a short time until this side effect improves.

Effects on the heart

Osimertinib can affect the way the heart works and, rarely, may cause a fast heartbeat. You may have tests such as an ECG to see how well your heart is working. These may be done before, during, and sometimes after treatment.

If you have changes to your heart, your doctor may tell you to stop taking osimertinib for short time until this side effect improves.

Contact a doctor straight away if you:

  • have pain or tightness in your chest
  • feel breathless or dizzy
  • feel your heart is beating too fast or too slowly.

Other conditions can cause these symptoms, but it is important to get them checked by a doctor.

Other information

Blood clot risk

Cancer and some cancer treatments can increase the risk of a blood clot. Symptoms of a blood clot include:

  • throbbing pain, redness or swelling in a leg or arm
  • suddenly feeling breathless or coughing
  • sharp chest pain, which may be worse when you cough or take a deep breath.

If you have any of these symptoms, contact the hospital straight away on the 24-hour contact number you have been given. If you cannot get through to your doctor, call the NHS urgent advice number on 111.

A blood clot is serious, but it can be treated with drugs that thin the blood (anticoagulants). Your doctor or nurse can give you more information.

You can help reduce the risk of developing a blood clot by:
  • staying active during treatment
  • drinking plenty of fluids, especially water.

You may be given anticoagulants to help prevent a clot.

Other medicines

Some medicines can affect osimertinib or be harmful when you are having it. This includes medicines you can buy in a shop or chemist. Tell your cancer doctor about any drugs you are taking, including vitamins, herbal drugs and complementary therapies.


Vaccinations can reduce your risk of getting certain infections. Your doctor or nurse may talk to you about having vaccinations.

Doctors usually recommend that people with cancer have a flu vaccination and a coronavirus vaccination. These are both inactivated vaccinations that can help reduce the risk of infection. People with weak immune systems can have these, as they are not live vaccinations.

If your immune system is weak, you need to avoid live vaccinations. This is because they can make you unwell. Live vaccines, such as shingles, contain a very weak version of the illness they are vaccinating you against. Your cancer doctor or GP can tell you more about live and inactivated vaccinations.


Your doctor will advise you not to get pregnant or make someone pregnant while having this treatment. The drugs may harm a developing baby. It is important to use contraception during your treatment.

If you take the contraceptive pill it may not be as effective while you are taking osimertinib.


You are advised not to breastfeed while having this treatment, or for some time after treatment finishes. This is because the drugs could be passed to the baby through breast milk.

Your doctor or nurse can give you more information.


Some cancer drugs can affect whether you can get pregnant or make someone pregnant. If you are worried about this, it is important to talk with your doctor before you start treatment.

Medical and dental treatment

If you need medical treatment for any reason other than cancer, always tell the doctors and nurses you are having cancer treatment. Give them the contact details for your cancer doctor so they can ask for advice.

If you think you need dental treatment, talk to your cancer doctor or nurse. Always tell your dentist you are having cancer treatment.