Alpelisib

Say it: al-peh-LIS-ib · Brand names: Piqray

Alpelisib is a targeted therapy pill that blocks a growth signal in breast cancers with a PIK3CA gene change.

What it is

Some breast cancers have a change in a gene called PIK3CA. This change makes a protein called PI3K stay turned on, which tells cancer cells to grow. Alpelisib blocks this protein and is given with fulvestrant.

Often used for

• hormone receptor positive, HER2 negative breast cancer with a PIK3CA gene change that is advanced or has spread, given with fulvestrant

How you get it

Alpelisib is a pill you take by mouth at home, once a day with food. Your schedule may be different.

Common side effects and what helps

• High blood sugar, which is very common. Your team will check your blood sugar often and may give you medicine for it.
• Diarrhea. Drink plenty of fluids. Tell your team early, since they may give you medicine to help.
• Rash. Your team may give you a medicine to help prevent it. Use gentle soap and fragrance free lotion.
• Feeling sick to your stomach or throwing up. Eat small meals and ask your team about anti-nausea medicine.
• Feeling tired or weak. Rest when you need to, and try short walks.
• Not feeling hungry or losing weight. Try small, frequent meals and snacks.
• Mouth sores. Brush gently with a soft toothbrush and rinse with a mild salt water rinse. Avoid spicy foods.
• Hair thinning. This usually grows back after treatment.

Call your care team right away if you have

• Signs of high blood sugar, such as feeling very thirsty, peeing a lot, or feeling confused
• Fruity smelling breath, belly pain, or fast breathing
• A rash with blisters, peeling skin, or sores in your mouth or eyes
• Swelling of your face or throat, or trouble breathing after a dose
• New or worse cough, chest pain, or trouble breathing
• Diarrhea that does not get better with the medicine your team gave you, or more than 4 to 6 loose stools in a day

Before you start, tell your team

• If you are pregnant, may become pregnant, or are breastfeeding
• If you have diabetes or high blood sugar
• If you have had a severe skin reaction to a medicine
• All the medicines, vitamins, and herbal products you take, since some can change how this medicine works

Good to know

• You will check your blood sugar often, especially in the first weeks. Your team may ask you to check it at home.
• It can cause severe skin reactions and allergic reactions.
• Rarely, it can cause lung inflammation.
• This medicine can harm an unborn baby. Use birth control during treatment and for some time after. Ask your team how long.

At home

• Take the tablets at about the same time each day with food.
• Swallow the tablets whole. Do not chew, crush, or split them.
• If you miss a dose or throw up after taking it, ask your team what to do. Do not take extra pills to make up for it.
• Store the pills at room temperature in the original bottle, away from children and pets.

Questions to ask

• How long will I take this medicine?
• How should I check my blood sugar at home?
• What foods should I limit while taking this?
• Which side effects should I call about right away, and which can wait until my next visit?

Side effect guides

• Fatigue (tiredness)
• Nausea and vomiting
• Diarrhea
• Mouth sores
• Hair loss
• Skin rash (including EGFR-inhibitor rash)

Last updated: 2026-10-27. Medically reviewed by Veli Bakalov, MD, medical oncologist (October 2026). General education from Step by Step, the patient portal of HemeOncBuddy.