Do not take this medicine with any of the following medications:

-cisapride
-dronedarone
-pimozide
-thioridazine

This medicine may also interact with the following medications:

-certain antibiotics like erythromycin or clarithromycin
-certain antivirals for HIV or hepatitis
-certain medicines for fungal infections like ketoconazole, itraconazole, or posaconazole
-certain medicines for seizures like carbamazepine, phenobarbital, phenytoin
-diltiazem
-grapefruit juice
-other medicines that prolong the QT interval (an abnormal heart rhythm)
-repaglinide
-St. John''s Wort
-stomach acid blockers like cimetidine, famotidine, ranitidine, lansoprazole, omeprazole, or pantoprazole
-verapamil

They need to know if you have any of these conditions:

-having surgery or recent surgery
-high blood pressure
-history of irregular heartbeat
-liver disease
-an unusual or allergic reaction to selpercatinib, other medicines, foods, dyes or preservatives
-pregnant or trying to get pregnant
-breast-feeding

Visit your health care professional for regular checks on your progress. Tell your health care professional if your symptoms do not start to get better or if they get worse.

You may need blood work done while you are taking this medicine.

If you are going to need surgery or other procedure, tell your health care professional that you are using this medicine.

Do not become pregnant while taking this medicine or for 1 week after stopping it. Women should inform their health care professional if they wish to become pregnant or think they might be pregnant. Men should not father a child while taking this medicine and for 1 week after stopping it. There is potential for serious side effects to an unborn child. Talk to your health care professional for more information.

Do not breast-feed a child while taking this medicine or for 1 week after stopping it.

This medicine may increase your risk to bruise or bleed. Call your health care professional if you notice any unusual bleeding.

Your mouth may get dry. Chewing sugarless gum or sucking hard candy and drinking plenty of water may help. Contact your health care professional if the problem does not go away or is severe.

This medicine may increase your risk of getting an infection. Call your health care professional for advice if you get a fever, chills, or sore throat, or other symptoms of a cold or flu. Do not treat yourself. Try to avoid being around people who are sick.

Avoid taking medicines that contain aspirin, acetaminophen, ibuprofen, naproxen, or ketoprofen unless instructed by your health care professional. These medicines may hide a fever.

This medicine has caused ovarian failure in some women. This medicine may make it more difficult to get pregnant. Talk to your health care professional if you are concerned about your fertility.

This medicine has caused decreased sperm counts in some men. This may make it more difficult to father a child. Talk to your health care professional if you are concerned about your fertility.

Keep out of the reach of children.

Store at room temperature between 15 and 30 degrees C (59 and 86 degrees F).