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Learn about alpelisib, a targeted biological therapy used to treat certain types of breast cancer. You may also hear it referred to by its brand name, Piqray.

1. What is alpelisib?

Alpelisib is a targeted (biological) therapy. Targeted therapies interfere with processes in cells that help cancer grow. Alpelisib belongs to a group of drugs called PI3K (phosphatidylinositol-3-kinase) inhibitors.

Alpelisib is the drug’s non-branded name. You may hear it called by its brand name Piqray.

2. Who might be offered alpelisib?

Alpelisib is used to treat breast cancer that’s oestrogen receptor positive and negative and has changes (mutations) in a gene called PIK3CA. It’s given alongside the hormone therapy drug fulvestrant.

You may be offered alpelisib if your breast cancer has a PIK3CA gene mutation and you have already had hormone therapy alongside a CDK 4/6 inhibitor (abemaciclib, palbociclib or ribociclib) for breast cancer that has:

  • Spread to the tissues and lymph nodes around the chest, neck and under the breastbone (locally advanced breast cancer)
  • Spread to another part of the body such as the bones, lungs, liver or brain (secondary breast cancer)

Alpelisib is not currently given for early (primary) breast cancer, though clinical trials are looking at whether it may be useful.

How do I know if my breast cancer has a PIK3CA gene mutation?

A PIK3CA mutation is not inherited (it cannot be passed on). It’s more common in oestrogen receptor positive and HER2 negative breast cancer.  

Oestrogen receptor positive breast cancers can be tested for a PIK3CA mutation. This is done in a laboratory on a sample of breast cancer tissue removed during a biopsy. Your treatment team may discuss performing a biopsy of the breast cancer to test for this.

If the biopsy shows that your breast cancer has a PIK3CA mutation, you may be offered alpelisib as part of your treatment. 

3. How alpelisib works

Targeted therapies block the growth and spread of cancer.

Alpelisib works by targeting breast cancer cells that have a genetic change (mutation) called PIK3CA. In breast cancers with a PIK3CA gene mutation, a protein called PI3K is involved in helping the cancer cells multiply and grow.

By blocking the action of PI3K, alpelisib helps stop the growth and spread of the cancer.

4. How alpelisib is given

Alpelisib is taken once a day. The usual dose of alpelisib is 300mg, taken as two 150mg tablets. The tablets should be swallowed whole with water (do not crush, chew or dissolve them). They should be taken after food, around the same time each day.

Fulvestrant is given as two injections, one in each buttock. They are usually given every 14 days for the first three doses, then every 28 days for as long as you are having alpelisib. 

How long is it given for?

You’ll have alpelisib for as long as your treatment team feels you’re benefiting from the drug and any side effects are manageable.

Alpelisib and menopause

Fulvestrant is suitable for women who have been through the menopause (when your periods stop).

If you have not been through the menopause, you will also have treatment to stop your ovaries producing oestrogen, either temporarily or permanently. This is known as .

5. Side effects of alpelisib

Like any drug, alpelisib can cause side effects.

Everyone reacts differently to drugs and some people have more side effects than others. These side effects can usually be managed and those described here will not affect everyone.

Because it’s given alongside fulvestrant, you may also have side effects from that drug as well.

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

You should be given a 24-hour contact number or told who to contact if you feel unwell or are concerned about side effects at any time, including at night or at the weekend.

Common side effects

Raised blood sugar levels (hyperglycaemia)

Alpelisib can cause your blood sugar levels to increase. If you notice you are more thirsty than usual or passing urine more often than normal let your treatment team know.

Other symptoms may include feeling more tired than usual, increased appetite but with weight loss, confusion, nausea, vomiting, a fruity odour on your breath, difficulty breathing or flushed skin.

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

Skin changes

Alpelisib may cause skin changes. Some of them may be severe including:

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

Less commonly skin changes may be accompanied by flu-like symptoms.

It may help to:

  1. Use a moisturiser regularly and avoid perfumed products
  2. Wear gloves when washing up, using harsh detergents, gardening or cooking
  3. Rinse and dry your hands carefully, particularly after contact with cleaning products
  4. Pat your skin dry with a soft towel, rather than rubbing vigorously
  5. Take care when shaving
  6. Wear cotton clothes where possible and wash clothes in mild detergent


Diarrhoea is a very common side effect of alpelisib and can sometimes be severe. 

Your treatment team or GP may prescribe anti-diarrhoea medication to take home.

If you experience diarrhoea it’s recommended you start the anti-diarrhoea medication straight away, drink plenty of fluids and contact your treatment team.

If you develop severe diarrhoea while taking alpelisib, your specialist may reduce the dose, or stop your treatment.

Nausea and vomiting

You may feel sick (nausea) and be sick (vomit).

Anti-sickness drugs can be prescribed to help with this. If you still experience nausea or vomiting contact your treatment team as they may be able to recommend a different anti-sickness drug and change your prescription. 

Try to eat small regular meals if possible and drink plenty of fluids.

Loss of appetite

You may not feel like eating, especially if you feel sick. Your sense of taste can also change, and some foods and drinks may taste different. It might help to eat small meals regularly and drink plenty of fluids. You can ask your GP or treatment team to refer you to a dietitian for more advice.

Find out more about diet and breast cancer treatment.

Effects on the blood

Alpelisib can temporarily affect the number of blood cells in the body.

You’ll have regular blood tests to check your blood count. Blood is made up of red cells, white cells and platelets. If 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 the risk of getting an infection such as a urine infection (UTI).

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 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 

Before starting alpelisib you should be given a 24-hour contact number or told where to get emergency care by your treatment team. You may need antibiotics.


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

Bruising and bleeding

Alpelisib 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 experience any of these symptoms.

Cancer-related fatigue (extreme tiredness)

Cancer-related fatigue is extreme tiredness that doesn’t go away with rest or sleep.

It’s a very common side effect of breast cancer treatment and may affect you physically and emotionally. 

It has many causes, from psychological factors such as the stress of coping with the diagnosis, to physical ones such as the side effects of treatment or progression (growth and spread) of the cancer. 

If you have fatigue, tell your GP or treatment team so you can be fully assessed and offered advice on how to manage your energy levels.

Find out more about managing fatigue.

Hair thinning or hair loss

Hair thinning and hair loss are very common when taking alpelisib with fulvestrant.

Find out more about breast cancer and hair loss.

Sore mouth 

Looking after your mouth, including your teeth and gums, is very important during treatment. Your mouth may become sore, dry or painful and you may get ulcers. It’s advisable to see your dentist for a dental check-up before your treatment begins. Check with your treatment team before having any dental work done.

Other common side effects include:

  • Headaches
  • Weight loss
  • Abdominal pain
  • Indigestion
  • Swelling (oedema) particularly of the hands and legs
  • High temperature

Your treatment team can advise you on how to manage these.

Less common side effects

Damage to the lungs

Alpelisib 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

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

If alpelisib has caused scarring to your lungs, you may need to stop treatment temporarily and have steroids to treat the ILD.

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

Osteonecrosis of the jaw

Osteonecrosis is a condition where a loss of blood flow to bone tissue causes the bone to die. It’s a less common but serious long-term side effect of alpelisib. It can affect the jaw, causing symptoms such as: 

  • Lasting jaw pain 
  • Loose teeth 
  • Swelling, redness or ulcers on the gums 

Looking after your mouth, including your teeth and gums, can help reduce the risk. See your dentist for a check-up before starting treatment. Any dental work should be done before you start treatment. 

Less commonly osteonecrosis can affect the ear. 

If you have any ear pain, discharge from your ear or an ear infection while taking alpelisib contact your treatment team.

Alpelisib is not recommended for people who already have osteocronosis of the jaw from other treatments such as bone-strengthening drugs.

Other less common side effects include:

  • Dehydration
  • Kidney problems
  • Blurred vision and dry eyes
  • Difficulty sleeping (insomnia)
  • High blood pressure
  • Toothache, gum disease, gum pain and inflammation of the lips
  • Muscle aches, pains and spasms

6. Other important information

Allergic reaction

Allergic reactions to alpelisib can occur. Reactions can vary from mild to severe.

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

Symptoms include flushing, skin rash, itching, back pain, shortness of breath, faintness, fever or chills.

If you have any of these symptoms, let your treatment team know immediately. 

Blood clots  

People with breast cancer have a higher risk of blood clots such as a deep vein thrombosis (DVT). Their risk is higher because of the cancer itself and some treatments for breast cancer. If the cancer has spread to other parts of the body, this also increases the risk.

People with a DVT are at risk of developing a pulmonary embolism (PE). This is when part of the blood clot breaks away and travels to the lung. 

Blood clots can be harmful but are treatable so it’s important to report symptoms as soon as possible.

Blood clot symptoms

If you have any of the following symptoms, contact your treatment team or go to your local A&E department immediately:

  • Pain, redness/discolouration, 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.

Medicines and food to avoid when having alpelisib

A number of drugs should not be taken with alpelisib, such as medicines for acid reflux or heartburn. Tell your treatment team about any prescribed or over-the-counter medicines you are taking.

Many people consider taking herbal medicines or supplements while having treatment for breast cancer. Ask your treatment team before taking any herbal medicines or supplements.

Sex and contraception

It’s important not to get pregnant when having alpelisib as it may have a harmful effect on a developing baby.

Some women can still become pregnant even if their periods are irregular or have stopped.

Use an effective barrier method of contraception during treatment and for at least one week after the last dose.

If you have not been through the menopause, talk to your treatment team about the most suitable method of contraception for you. 

Men having alpelisib who have a female sexual partner should use condoms during sexual intercourse while taking alpelisib and for at least one week after the last dose.


Alpelisib may affect fertility in both women and men. It’s important to discuss any fertility concerns with your treatment team before you begin treatment.


Breastfeeding is not recommended while having alpelisib, or for at least a week after the last dose. This is because there’s a risk the drugs could be passed on through breast milk.

Travel and vaccinations

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

You shouldn’t have any live vaccines while you’re having treatment.

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

Live vaccines contain a small amount of live virus or bacteria. If you have a weakened immune system, which you may do during treatment, they could be harmful.

It’s safe to have these vaccinations six months after your treatment finishes. Talk to your GP or treatment team before having any vaccinations.

If anyone 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, chemotherapy. 

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

Coronavirus (Covid-19) vaccination  

People having alpelisib are advised to speak to their treatment team before having a coronavirus (Covid-19) vaccination.

Find out more about coronavirus vaccines

7. Further support

Being diagnosed with secondary 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.

Our Living with Secondary Breast Cancer groups let you share experiences with other people dealing with the uncertainty and challenges of secondary breast cancer.

Find out more about our support services below.

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Quality assurance

This information was published in July 2022. We will revise it in July 2024.

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