8 Verzenio Side Effects and How to Manage Them

Verzenio (abemaciclib) is a targeted therapy medication that treats hormone receptor-positive/HER2-negative breast cancer. It's often taken in combination with hormone therapy, but you can also take it by itself. It's an oral tablet that's taken twice a day. 

Verzenio works in a more targeted way than traditional chemotherapy. It blocks enzymes called cyclin-dependent kinases (CDKs), which are proteins that contribute to uncontrolled growth in breast cancer cells. By blocking these enzymes, Verzenio is able to slow the growth of cancer.

Like most medications, Verzenio can cause side effects. Many side effects are mild and manageable at home. But some side effects can become serious and require immediate medical attention.

Verzenio side effects at a glance

The most common side effects of Verzenio include:

• Diarrhea

• Low white blood cell counts

• Low red blood cell counts

• Low platelets

• Fatigue

• Nausea

• Infections

• Vomiting

• Hair thinning or hair loss

• Headache

• Decreased appetite

• Stomach pain

• Elevated liver enzyme levels

Rare but serious Verzenio side effects include:

• Severe diarrhea

• Lung problems

• Liver problems

• Blood clots

• Harm to an unborn baby

Here’s a deeper dive into eight Verzenio side effects and how to manage them.

1. Low blood cell counts

Verzenio can lower your blood cell counts, including your red blood cells, white blood cells, and platelets. Low blood cell counts raise your risk of developing anemia, feeling tired, and getting an infection. It can also make you bruise or bleed more easily than normal.

Your oncologist should check your blood cell counts every couple weeks when you first start taking Verzenio. They’ll do this to make sure your blood counts aren’t getting too low. If your blood counts do drop too low, your oncologist may need to adjust your dose of Verzenio or recommend you stop taking it.

EXPERT PICKS: WHAT TO READ NEXT

• Does Verzenio keep cancer from coming back? See how effective Verzenio is for treating early breast cancer.

• Early breast cancer treatment: Find out more about early breast cancer treatments, from chemotherapy to hormone therapy.

• Verzenio interactions: Learn about Verzenio’s top medication interactions and how to manage them.

2. Diarrhea

Diarrhea is a very common side effect of Verzenio. In fact, up to 90% of people who took Verzenio in clinical trials had diarrhea. It usually happens within the first month of starting Verzenio and may get better within a couple weeks. 

It’s not entirely understood why Verzenio causes diarrhea. But it’s likely due to Verzenio’s metabolism and off-target effects. It's important not to ignore it if it happens, as diarrhea can become severe and lead to dehydration if left unaddressed.

Your oncologist will likely prescribe an antidiarrheal medication, such as loperamide (Imodium A-D), to have on hand when you start Verzenio. You can take loperamide at the first sign of a loose stool. It also helps to drink plenty of clear fluids and let your healthcare team know right away that you’re experiencing diarrhea. 

If diarrhea doesn't resolve within 24 hours, your oncologist may recommend you temporarily stop taking Verzenio. They may restart you at a lower dose after the diarrhea goes away.

3. Nausea and vomiting

Nausea and vomiting are relatively common with Verzenio. You can take Verzenio with or without food, but taking it with food may help ease nausea. Just make sure to avoid large meals and spicy or greasy foods that may upset your stomach.

Your oncologist may also prescribe an antinausea medication, such as ondansetron or prochlorperazine. You can take antinausea medications alongside Verzenio to help stop nausea and vomiting before it starts. Let your healthcare team know if you have uncontrolled nausea and vomiting at any point, because it can lead to dehydration.

Good to know: If you vomit shortly after taking a dose of Verzenio, take your next dose at the next scheduled time. You don't need to double up on doses.

4. Infection

Verzenio can cause your white blood cell counts to drop, which can lead to neutropenia. This is when neutrophils, a type of white blood cell, get too low. It raises your risk of infection. 

If you develop neutropenia while taking Verzenio, your oncologist may ask you to stop taking it while your blood cell counts recover. They may recommend restarting Verzenio at a lower dose after the neutropenia has resolved.

Having a fever with neutropenia is especially dangerous. Your immune system is weakened, so a fever may be the only noticeable symptom of infection. Check your temperature regularly and let your healthcare team know right away if you start to feel sick, have a new cough or chills, or have a temperature of 100.4 F° or higher.

5. Hair loss or thinning

Verzenio can cause hair loss or hair thinning. This usually happens about 2 to 3 months after starting Verzenio. In a clinical study, nearly 30% of people who took Verzenio alongside an aromatase inhibitor experienced hair thinning or hair loss. 

You can manage hair thinning or hair loss while taking Verzenio by:

• Brushing or combing hair gently

• Using mild, gentle shampoos for hair washing

• Avoiding frequent use of heat styling tools, such as hair dryers and hair curlers

• Getting a wig or trying a new hairstyle

Talk to your oncologist if you’re concerned about hair loss or hair thinning. They may be able to recommend other options for managing hair loss.

6. Blood clots

Although uncommon, Verzenio may cause blood clots. These can be life-threatening. In clinical trials, up to 5% of people had blood clots. 

You can have blood clots in different areas of the body including the legs, thighs, or pelvis. They can travel to the lungs (pulmonary embolism). Symptoms of a blood clot include shortness of breath, pain or swelling in your arms or legs, and fast heart rate. If you experience any symptoms like these, call 911 or go to the ER immediately.

If you experience blood clots while taking Verzenio, you'll likely need to stop taking it — temporarily or altogether.

7. Liver problems

Verzenio may raise liver enzyme levels, which may indicate liver problems. This usually happens about 2 to 6 months after starting Verzenio. 

Your oncologist should regularly monitor your liver enzyme levels while you’re taking Verzenio. If your liver enzyme levels become high, your oncologist may recommend you stop taking Verzenio or lower your dose. 

Elevated liver enzymes often come with no noticeable symptoms. But potential symptoms of liver problems include feeling tired, losing your appetite, and having pain in the right side of your stomach. You may also bleed or bruise more easily than normal. Let your healthcare team know if you have any of these symptoms. 

To help lower your risk of liver problems, avoid alcohol and other medications that can irritate your liver, such as acetaminophen (Tylenol).

8. Lung problems

Although rare, Verzenio can cause serious lung problems, including interstitial lung disease (ILD). ILD can become life-threatening, so let your healthcare team know right away if you develop new or worsening breathing problems, cough, or chest pain. You may need to stop taking Verzenio temporarily or lower your dose.

Your oncologist will likely recommend having your lungs assessed if you develop symptoms like shortness of breath, dry cough, or chest discomfort while taking Verzenio. If you develop severe ILD, you'll likely need to stop taking Verzenio altogether.

Why trust our experts?

Written by:

Sonja Jacobsen, PharmD, BCPS, BCOP

Sonja Jacobsen, PharmD, BCPS, BCOP,  is a clinical oncology pharmacy specialist currently practicing in Seattle. She has been practicing as a pharmacist since 2015 and is licensed to practice in Washington state and North Carolina.

Edited by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Vanessa Carranza, PharmD

Vanessa Carranza, PharmD, is a pharmacist who has dedicated her career to the advancement of medical education for healthcare providers, patients, and caregivers, most notably in the oncology space.

Our editorial standards

Meet our experts