What is Selpercatinib used for?

non-small cell lung cancer with a RET gene change; thyroid cancers with a RET gene change, including medullary thyroid cancer; other solid tumors with a RET gene change.

What are the common side effects of Selpercatinib?

Swelling in the legs, feet, hands, or face. Diarrhea or constipation. Dry mouth. High blood pressure. Feeling tired. Belly pain, nausea, or headache. Rash.

When should I call my care team while taking Selpercatinib?

Yellow skin or eyes, dark urine, or pain on the right side of your belly; New or worse cough, shortness of breath, or chest pain; Bad headache, or blood pressure higher than your team told you to expect; A fast, slow, or pounding heartbeat, or feeling like you might faint; Bleeding that will not stop, black or bloody stools, or coughing up blood; Fever, rash, or muscle and joint pain in the first few weeks, which can be an allergic reaction.

Selpercatinib

Say it: sel-per-KA-tih-nib · Brand names: Retevmo

Selpercatinib is a targeted pill that blocks a growth signal in cancers with a change in the RET gene.

What it is

Some cancers have a change in a gene called RET. This change tells cancer cells to keep growing. Selpercatinib blocks the RET signal very closely, with fewer effects on other parts of the body.

Often used for

non-small cell lung cancer with a RET gene change
thyroid cancers with a RET gene change, including medullary thyroid cancer
other solid tumors with a RET gene change

How you get it

It is a capsule or pill you take by mouth twice a day. People usually take it for as long as it works. Your schedule may be different.

Common side effects and what helps

Swelling in the legs, feet, hands, or face. Raise your legs when sitting.
Diarrhea or constipation. Drink plenty of fluids and ask your team which medicine to keep at home.
Dry mouth. Sip water often and try sugar-free gum.
High blood pressure. Your team will check it at visits.
Feeling tired. Rest when you need to and take short walks when you can.
Belly pain, nausea, or headache. Tell your team if it bothers you.
Rash. Use gentle soap and moisturizer.

Call your care team right away if you have

Yellow skin or eyes, dark urine, or pain on the right side of your belly
New or worse cough, shortness of breath, or chest pain
Bad headache, or blood pressure higher than your team told you to expect
A fast, slow, or pounding heartbeat, or feeling like you might faint
Bleeding that will not stop, black or bloody stools, or coughing up blood
Fever, rash, or muscle and joint pain in the first few weeks, which can be an allergic reaction

Before you start, tell your team

If you take medicines for heartburn or stomach acid, since timing matters
If you have heart, liver, or bleeding problems
If you have surgery planned, since it can slow wound healing
If you are pregnant, may become pregnant, or are breastfeeding
All the medicines, vitamins, and herbal products you take, since some can change how this medicine works

Good to know

You will have regular blood tests to check your liver, especially in the first months.
You will have blood pressure checks and may have an ECG (a heart tracing).
It can slow wound healing. Your team may stop it for a while before and after surgery.
It can lower thyroid hormone. You will have thyroid blood tests.
In children, it can affect bone growth, so growth is watched closely.

At home

Take it at about the same times each day. If you also take a stomach acid medicine, ask your team whether to take this medicine with food.
Swallow the pills whole with water. Do not crush, chew, or split them unless your team says it is OK.
If you miss a dose or throw up after a dose, ask your team what to do. Do not take an extra dose on your own.
Store the pills at room temperature in their original container, away from children and pets.
Wash your hands after touching the pills. Ask your team if others in your home should take special care.
Do not eat grapefruit or drink grapefruit juice, since it can raise the amount of medicine in your blood.

Questions to ask

How long will I take this medicine?
What tests will I need, and how often?
Are any of my other medicines, foods, or supplements a problem with this medicine?
What should I do if I miss a dose?
Which side effects should I call you about right away, and which can wait?

Side effect guides

Sources

Quick answers

What is Selpercatinib?: Selpercatinib is a targeted pill that blocks a growth signal in cancers with a change in the RET gene. Brand names: Retevmo.
What is Selpercatinib used for?: non-small cell lung cancer with a RET gene change; thyroid cancers with a RET gene change, including medullary thyroid cancer; other solid tumors with a RET gene change.
How is Selpercatinib given?: It is a capsule or pill you take by mouth twice a day. People usually take it for as long as it works. Your schedule may be different.
What are the common side effects of Selpercatinib?: Swelling in the legs, feet, hands, or face. Diarrhea or constipation. Dry mouth. High blood pressure. Feeling tired. Belly pain, nausea, or headache. Rash.
When should I call my care team while taking Selpercatinib?: Yellow skin or eyes, dark urine, or pain on the right side of your belly; New or worse cough, shortness of breath, or chest pain; Bad headache, or blood pressure higher than your team told you to expect; A fast, slow, or pounding heartbeat, or feeling like you might faint; Bleeding that will not stop, black or bloody stools, or coughing up blood; Fever, rash, or muscle and joint pain in the first few weeks, which can be an allergic reaction.

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.