Learn more about everolimus (Afinitor), including what it is, how it's given and its side effects.

1. What is everolimus?

Everolimus is a targeted therapy.

This group of drugs block the growth and spread of cancer. They target and interfere with processes in the cells that help cancer grow.  

Everolimus is the drug’s non-branded name. Its brand name is Afinitor.

Everolimus is taken in combination with the drug exemestane.

2. Who might be offered everolimus?

Everolimus is used to treat:

You may be offered everolimus if:

  • You have ER-positive, HER2-negative, locally advanced or secondary breast cancer
  • Your cancer has come back during or after taking the hormone therapy drugs letrozole or anastrozole
  • And you are post-menopausal (no longer have periods)

Everolimus is not currently given for .

If you haven’t been through the menopause

If you haven’t been through the menopause (premenopausal), you might be prescribed everolimus and exemestane in combination with a treatment to stop your ovaries producing the hormone oestrogen, either temporarily or permanently. This is known as ovarian suppression.

3. How everolimus works

Everolimus belongs to a group of drugs called mTOR inhibitors. mTOR is a protein that affects how cancer cells divide and grow. Everolimus works by blocking mTOR, which helps to stop or slow down the growth of the cancer.

4. How everolimus is taken

You take everolimus as a tablet once a day.

You should take it whole, with water at the same time each day. You can take it with or without food.

What happens if I miss a dose?

If you miss a dose of everolimus or are sick (vomit) soon after taking it, do not take an extra dose to make up for the one you missed. Take the next dose at the usual time and speak to someone in your treatment team.

How long will I take everolimus for?

You’ll have everolimus alongside exemestane for as long as your treatment team feels you’re benefitting from it and any side effects are manageable.

5. Side effects of everolimus

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Like any treatment, everolimus can cause side effects. Everyone reacts differently to drugs and some people have more side effects than others. These side effects can usually be controlled and those described here will not affect everyone.

Because everolimus is given with exemestane, you may have side effects from that drug as well.

Doctors can tailor the dose of a drug by reducing it to suit an individual and to help manage its side effects. This can help some people stay on a treatment for longer.

If you’re worried about any side effects, regardless of whether they’re listed here, talk to your treatment team as soon as possible.

Common side effects of everolimus

Effects on the blood

Everolimus can temporarily affect the number of blood cells in the body. Blood is made up of red cells, white cells and platelets.

You’ll have regular blood tests. If these show the number of blood cells is too low, your next cycle of treatment may be delayed or the dose reduced. 

Risk of infection

Not having enough white blood cells can increase your risk of getting an infection.

Signs of an infection

Your treatment team may give you guidelines to follow for reporting signs of an infection. But generally you should contact your hospital advice line immediately if you experience any of the following:  

  • A high temperature (over 37.5°C) or low temperature (under 36°C), or whatever your treatment team has advised  
  • Suddenly feeling unwell, even with a normal temperature  
  • Symptoms of an infection, for example a sore throat, a cough, a need to pass urine frequently or feeling cold or shivery 
Anaemia

Having too few red blood cells is called anaemia. If you feel breathless, dizzy or particularly tired, let your treatment team know.

Bruising and bleeding

Everolimus can reduce the number of platelets, which help the blood to clot.

You may bruise more easily, have nosebleeds or your gums may bleed when you brush your teeth.

Tell your treatment team if you have any of these symptoms.

Sore mouth

Looking after your mouth, including your teeth and gums, is very important during treatment. 

You’ll be given mouthwash to try to reduce soreness and stop mouth ulcers developing.  

See your dentist for a check-up before treatment begins. Avoid dental work during treatment if possible.

If you do need to have dental work during treatment, talk with your oncologist about the best time to have this. 

Taste changes

Your sense of taste may change and some food may taste different, for example more salty, bitter or metallic. 

It can help to try different types of food to see what tastes best to you.

Our information on diet during breast cancer treatment includes tips on dealing with taste changes.

Damage to the lungs

Everolimus can cause scarring or inflammation of the lungs. 

You may hear this called interstitial lung disease (ILD) or pneumonitis.

Contact your treatment team straight away if you have:

  • Shortness of breath
  • A cough, with or without a high temperature
  • Any new or worsening breathing problems, such as chest tightness or wheezing

You may need a chest x-ray or CT scan to check if you have ILD.  

If everolimus has caused inflammation to your lungs, you may need to stop treatment temporarily and have steroids to treat the inflammation. Early treatment of the inflammation can help prevent long-term damage to the lungs.

In some cases, lung damage from ILD can be permanent and may get worse over time. Treatment for ILD can relieve symptoms, improve quality of life and slow the progression of the disease.

Extreme tiredness (cancer-related fatigue)

Cancer-related fatigue is one of the most common symptoms in people with secondary breast cancer.

Fatigue is extreme tiredness that does not go away with rest or sleep. It has many causes, from the emotional impact of a diagnosis to side effects of treatment or growth and spread of the cancer.

Fatigue may affect how you cope with your cancer and its treatment. It can also make everyday activities harder and affect your quality of life.

If you think you have fatigue, tell your GP or treatment team. They can assess you and offer advice on how to manage your energy levels. 

Find out more about managing fatigue

Skin changes

You may get a rash and your skin may be itchy. Using a moisturiser regularly and a high-factor sunscreen in the sun may help.

Let your treatment team know if you have any skin changes as they may prescribe creams or tablets to help.

Diarrhoea

Your treatment team or GP can prescribe medicine to help control diarrhoea.

Contact your treatment team if you have diarrhoea 4 or more times in 24 hours.

Raised blood sugar levels (hyperglycaemia)

Everolimus can cause your blood sugar levels to increase. If you notice you are thirstier than usual or peeing more often than normal, let your treatment team know.

You’ll have regular blood tests to check your blood sugar levels while taking everolimus.

High cholesterol

Everolimus may cause your cholesterol levels to increase.

You’ll have regular blood tests while taking everolimus to check your cholesterol levels.

Feeling sick (nausea) and being sick (vomiting)

You may feel sick or be sick. Your treatment team can prescribe anti-sickness drugs to help with this.

If you still feel sick or are being sick, contact your treatment team as they may be able to recommend a different anti-sickness drug. 

Loss of appetite

You may not feel like eating, especially if you feel sick. It might help to eat small meals regularly and drink plenty of liquids. You can also ask your GP or treatment team to refer you to a dietitian for more advice.

Headaches

Everolimus may cause headaches. Tell your treatment team or GP about any headaches so they can assess you and help you manage them.

Less common side effects of everolimus

Kidney problems

Everolimus can affect how well your kidneys work. You’ll have regular blood tests while taking it to check how well they’re working. 

If you have difficulty peeing or are not passing as much urine as normal, let your treatment team or GP know.

Liver changes

Everolimus can affect how the liver works. You’ll have regular blood tests to check that your liver is working properly.

Your treatment may need to be delayed or the dose reduced if the blood tests show any problems with your liver.

Hand-foot (palmar-plantar) syndrome

You may develop soreness, redness and peeling on the palms of your hands and soles of your feet. This is known as hand-foot syndrome, and may cause tingling, numbness, pain and dryness. Redness may be harder to see if you have black or brown skin.

Keeping the feet and hands clean, dry and well moisturised can help.

If you have skin reactions, tell your treatment team so the symptoms can be managed.

Heart changes

Everolimus can cause changes to your heart, although this is uncommon. It’s usually temporary, but for a small number of people it may be permanent.

Contact your treatment team if you develop any breathlessness, chest pain, a cough or notice any swelling in your arms, legs or feet.

Slow wound healing

Everolimus may delay wound healing. If you need an operation you may have to stop taking everolimus for a short time and start it again once your wound has healed. Your treatment team can tell you more about this.

6. Other important information

Allergic reaction

If you have an allergic reaction to everolimus, it’s more likely to happen the first time you take it.

Contact your hospital immediately if you notice any of the following symptoms:

  • Itchy red/discoloured bumps on your skin (these may be harder to see on black or brown skin)
  • Swelling in your lips, tongue or throat
  • Breathlessness, wheezing, a bad cough or sudden difficulty breathing
  • Tight chest or chest pain

Blood clots

People with breast cancer have a higher risk of blood clots.

Having everolimus also increases the risk of blood clots such as a DVT (deep vein thrombosis).

If you have a DVT, there’s a risk part of the blood clot could break away and travel to the lung. This is known as a pulmonary embolism (PE).

Blood clots can be life-threatening and should be treated quickly.

Blood clot symptoms

Contact your treatment team or go to your local A&E department straight away if you have any of the following symptoms: 

  • Pain, redness/discolouration of the skin, heat and swelling of the arm or leg
  • 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
  • Pain or tightness in the chest
  • Unexplained cough or coughing up blood

Find out more about blood clots.

Hepatitis B

If you have had hepatitis B (a liver infection) in the past, everolimus can make the hepatitis infection active again. Let your treatment team know if you have ever had hepatitis.

Medicines and food to avoid when taking everolimus

When taking everolimus:

  • Do not take anything containing St John’s Wort
  • Do not eat grapefruit or drink grapefruit juice

There are a number of drugs that should not be taken with everolimus.

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 you a new drug, tell them you’re taking everolimus.

Ask your treatment team before taking any herbal medicines or supplements.

Everolimus contains lactose. If you know you’re lactose intolerant tell your treatment team before treatment begins.

Sex, contraception and pregnancy

Taking everolimus while pregnant may be harmful to a developing baby.

You can still become pregnant even if your periods have stopped with ovarian suppression or have become irregular. If you’re sexually active with a chance of becoming pregnant, your treatment team is likely to advise you to use a non-hormonal method of contraception, such as condoms and Femidoms, while taking everolimus and for up to 8 weeks after finishing treatment.

It may also be possible to use a coil (IUD or intrauterine device). However, you would need to discuss this with your treatment team as not all types are suitable for women with breast cancer.

Fertility

It’s not clear whether everolimus affects fertility but it’s thought it may decrease it.

If you were diagnosed with locally advanced or secondary breast cancer before you started or completed a family, you may be concerned about your fertility. Depending on your diagnosis and treatment, you may be advised not to get pregnant.

You can talk to your treatment team about any possible fertility preservation options before starting treatment.

Breastfeeding

You’ll be advised not to breastfeed during treatment and for at least 2 weeks after your last dose of everolimus. This is because there’s a chance your baby may absorb the drug through your breast milk, which might cause harm.

Vaccinations and travel

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 having treatment.

For more information about vaccines, including COVID-19 and flu vaccines, see our information on vaccines and breast cancer

7. Further support

If you’ve been diagnosed with breast cancer, it’s natural to feel lonely or isolated.

You may find it helpful to talk to someone who has been through a similar experience to you.

Our Living with Secondary Breast Cancer service can help you meet others in a similar situation, and offers helpful support and information in a relaxed environment – see below.

You might also find it helpful to join one of our Live Chat sessions, or visit our confidential online forum.

Find out more about our support services below.

 

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Quality assurance

This information was published in December 2024. We will revise it in December 2026.

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