Abemaciclib
Say it: a-BEM-a-SY-klib · Brand names: Verzenio
Abemaciclib is a targeted therapy pill that helps stop breast cancer cells from dividing.
What it is
Cancer cells use proteins called CDK4 and CDK6 to divide and make more cells. Abemaciclib blocks these proteins. It is usually given with hormone therapy.
Often used for
- hormone receptor positive, HER2 negative early breast cancer with a high chance of coming back, given with hormone therapy
- hormone receptor positive, HER2 negative breast cancer that is advanced or has spread
How you get it
Abemaciclib is a pill you take by mouth at home, twice a day, every day, with or without food. For early breast cancer it is usually taken for 2 years. Your schedule may be different.
Common side effects and what helps
- Diarrhea, which is very common, especially in the first month. At the first loose stool, start the diarrhea medicine your team told you to keep at home, and drink plenty of fluids.
- Low white blood cell counts, which raise your chance of infection. Wash your hands often.
- Feeling sick to your stomach or throwing up. Eat small meals and ask your team about anti-nausea medicine.
- Belly pain. Tell your team if it is new or gets worse.
- 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.
- Headache. Ask your team which pain medicines are safe.
Call your care team right away if you have
- Diarrhea that does not get better with the medicine your team gave you, or more than 4 to 6 loose stools in a day
- A fever of 100.4 degrees Fahrenheit (38 degrees Celsius) or higher, or chills
- New or worse cough, chest pain, or trouble breathing
- Yellow skin or eyes, dark tea colored urine, or pain on the right side of your belly
- Swelling, pain, or warmth in one leg, or sudden shortness of breath
Before you start, tell your team
- If you are pregnant, may become pregnant, or are breastfeeding
- If you have liver problems
- If you have had blood clots
- All the medicines, vitamins, and herbal products you take, since some can change how this medicine works
Good to know
- Diarrhea is common. Keep diarrhea medicine at home and follow your team's plan.
- You will have blood tests to check your blood counts and liver, every 2 weeks at first.
- It can raise the chance of blood clots and, rarely, 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 pills at about the same times each day.
- Swallow the pills whole.
- Do not eat grapefruit or drink grapefruit juice while taking this medicine.
- 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?
- Which diarrhea medicine should I keep at home?
- Is it safe to take my other medicines, vitamins, or supplements with this one?
- How will we know if this medicine is working?
Side effect guides
Sources
Quick answers
- What is Abemaciclib?
- Abemaciclib is a targeted therapy pill that helps stop breast cancer cells from dividing. Brand names: Verzenio.
- What is Abemaciclib used for?
- hormone receptor positive, HER2 negative early breast cancer with a high chance of coming back, given with hormone therapy; hormone receptor positive, HER2 negative breast cancer that is advanced or has spread.
- How is Abemaciclib given?
- Abemaciclib is a pill you take by mouth at home, twice a day, every day, with or without food. For early breast cancer it is usually taken for 2 years. Your schedule may be different.
- What are the common side effects of Abemaciclib?
- Diarrhea, which is very common, especially in the first month. Low white blood cell counts, which raise your chance of infection. Feeling sick to your stomach or throwing up. Belly pain. Feeling tired or weak. Not feeling hungry or losing weight. Headache.
- When should I call my care team while taking Abemaciclib?
- Diarrhea that does not get better with the medicine your team gave you, or more than 4 to 6 loose stools in a day; A fever of 100.4 degrees Fahrenheit (38 degrees Celsius) or higher, or chills; New or worse cough, chest pain, or trouble breathing; Yellow skin or eyes, dark tea colored urine, or pain on the right side of your belly; Swelling, pain, or warmth in one leg, or sudden shortness of breath.
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.