Nirogacestat is used in adults to treat a type of fibrous (connective) tissue tumors called desmoid-type fibromatosis (desmoid tumor).

Nirogacestat may also be used for purposes not listed in this medication guide.

Tell your doctor if you have:

• liver disease.

Nirogacestat can harm an unborn baby if the mother or the father is using this medicine.

• If you are a woman, you may need a pregnancy test to make sure you are not pregnant. Use birth control while using this medicine and for at least 1 week after your last dose.
• If you are a man, use birth control if your sex partner is able to get pregnant. Keep using birth control for at least 1 week after your last dose.
• Tell your doctor right away if a pregnancy occurs. Do not use this medicine if you are pregnant.

Nirogacestat may affect fertility in men or women. Pregnancy could be harder to achieve while either parent is using this medicine.

Do not breastfeed while using this medicine, and for at least 1 week after your last dose.

Use Nirogacestat (Oral) exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

Get emergency medical help if you have signs of an allergic reaction: hives, difficult breathing, swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

• diarrhea that does not go away after taking antidiarrheal medicines and lasting longer than a few days;
• changes in your menstrual periods, hot flashes, night sweats, or vaginal dryness;
• changing or new skin lesions;
• shortness of breath;
• signs of an electrolyte imbalance--increased thirst or urination, constipation, muscle weakness, leg cramps, numbness or tingling, feeling jittery, fluttering in your chest; or
• liver problems--loss of appetite, nausea, vomiting, stomach pain (upper right side), tiredness, itching, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Your treatment may be changed, or temporarily or permanently discontinued if you have certain side effects.

Common side effects may include:

• tiredness;
• rash;
• hair loss;
• headache;
• mouth sores;
• nausea, stomach pain;
• cough, shortness of breath; or
• cold symptoms such as stuffy nose, sneezing, sore throat.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Grapefruit, starfruit, and Seville oranges may interact with nirogacestat and cause side effects. Avoid consuming grapefruit, starfruit, or Seville orange products.

Avoid taking an antacid within 2 hours before or after you take nirogacestat.