What is Alpelisib used for?
Last updated September 7, 2026.
Alpelisib is a targeted cancer medicine that treats PIK3CA-mutated advanced breast cancer (brand name Piqray, given with fulvestrant) and PIK3CA-related overgrowth spectrum, or PROS (brand name Vijoice). It blocks PI3K alpha, a signaling protein that drives growth when the PIK3CA gene is mutated, so an FDA-approved test showing that mutation is required before you start. For breast cancer, it is used in postmenopausal women and in men whose hormone receptor-positive, HER2-negative cancer has progressed on endocrine therapy. For PROS, it is used in people age 2 and older whose overgrowth is severe enough to need medicine that works throughout the body. High blood sugar is the most common serious effect, so your team checks fasting glucose and A1c before treatment and repeats testing during it. Taking each dose with food at the same time daily, keeping your glucose log, and calling at the first sign of a rash keep most people on schedule.
What to do
- Confirm the mutation first: Ask your oncology team for the PIK3CA test result, since alpelisib is only approved when that mutation is present.
- Take it with food: Swallow whole tablets once daily right after a meal at about the same time each day, and skip a missed dose if more than 9 hours have passed.
- Track your blood sugar: Expect fasting glucose and A1c testing before you start and regular checks after, and report heavy thirst, frequent urination, or confusion the same day.
- Report rash early: Call your clinician at the first spots or itching, before it spreads, since early treatment usually lets you continue the drug.
- Have a diarrhea plan: Keep an antidiarrheal your clinician approved on hand, drink fluids, and report diarrhea that lasts beyond a day or comes with fever.
- Plan around pregnancy: Use effective contraception during treatment and for one week after the last dose, and do not breastfeed while taking alpelisib.
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