Key takeaways:
Verzenio (abemaciclib) is a prescription-only medication used to treat hormone receptor-positive (HR-positive) breast cancer. It comes as an oral tablet.
Common Verzenio side effects include diarrhea, low blood cell counts, and nausea. Hair loss or thinning is also possible. You can usually manage mild side effects on your own or with your oncologist’s support.
Serious Verzenio side effects are rare, but possible. This includes liver and lung problems, blood clots, and severe diarrhea. Serious infections are also possible. You may need to hold or stop treatment if serious side effects occur.
Save on related medications
Verzenio (abemaciclib) is a targeted therapy that treats hormone receptor-positive (HR-positive) and human epidermal growth factor receptor 2-negative (HER2-negative) breast cancer. It's an oral tablet that's taken twice a day. You can take Verzenio along with hormone therapy, but you can also take it by itself.
If you’re prescribed Verzenio, it’s helpful to know what side effects to expect. This can help you stay safe and know what steps to take if side effects occur.
Verzenio side effects at a glance
Below are lists of common as well as rare, but serious, side effects of Verzenio. Keep in mind that these aren’t complete lists. Be sure to discuss any side effects that occur during treatment with your oncologist, even if they aren't listed here.
The most common Verzenio side effects include:
Diarrhea
Low white blood cell counts
Nausea
Stomach pain
Infections
Fatigue
Low red blood cell counts
Decreased appetite
Vomiting
Hair thinning or hair loss
Headaches
Low platelet counts
Elevated liver enzyme levels
Rare but serious Verzenio side effects include:
Severe diarrhea
Lung problems
Liver problems
Blood clots
Harm to an unborn fetus
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 cell, white blood cell, and platelet counts. This may lead to anemia, tiredness, and an increased risk of infection. It can also make you bruise or bleed more easily than normal.
Your oncologist should check your blood cell counts every couple of weeks when you first start taking Verzenio. This is 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 Verzenio dosage or have you stop taking it.
2. Diarrhea
Diarrhea is a very common Verzenio side effect. It usually happens within the first month of starting the medication. It’s not entirely understood why Verzenio causes diarrhea. But it’s likely due to Verzenio’s off-target effects and how your body breaks it down.
Diarrhea from Verzenio may get better within a couple of weeks. But it's important not to ignore it, especially if it persists. 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), for you 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 to stay hydrated.
If you have diarrhea that doesn't resolve within 24 hours, let your cancer care team know right away. Your oncologist may recommend you stop taking Verzenio for a short time. They may also restart you at a lower dose after the diarrhea resolves.
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 further upset your stomach.
Your oncologist may also prescribe you an anti-nausea medication, such as ondansetron or prochlorperazine. You can take anti-nausea medication alongside Verzenio to help stop nausea and vomiting before they start or to reduce symptoms.
Let your cancer care team know if you have uncontrolled nausea and vomiting at any point.
Good to know: If you vomit shortly after taking a dose of Verzenio, simply take your next dose at the regularly scheduled time. Don’t take an extra dose or double up on doses.
4. Infection
Verzenio can cause your white blood cell counts to drop, which can lead to neutropenia. This is when the number of neutrophils, a type of white blood cell, in the body gets too low. Neutropenia raises your risk of infection.
As mentioned, your oncologist should keep an eye on your blood cell counts while you’re taking Verzenio. If you develop neutropenia, they may have you stop taking Verzenio until your blood cell counts recover. They may also have you restart Verzenio at a lower dose to help avoid this issue in the future.
A fever is especially concerning if you develop neutropenia. It may be the only sign you’ve developed an infection. So it’s a good idea to check your temperature regularly while you’re taking Verzenio. And let your cancer care team know right away if you start to feel sick, have a new cough or chills, or develop a fever of 100.4°F or higher.
5. Hair loss or thinning
Like many cancer treatments, Verzenio can cause hair loss or hair thinning. This usually happens about 2 to 3 months after starting Verzenio. But it doesn’t happen to everyone. In a clinical study, a little less than 30% of people who took Verzenio alongside an aromatase inhibitor reported hair thinning or hair loss.
You can manage hair thinning or hair loss while taking Verzenio by:
Brushing or combing your hair gently
Using mild, gentle shampoos to wash your hair
Avoiding frequent use of heat styling tools, such as hair dryers and curling irons
Wearing a wig, scarf, or hat
Choosing a shorter 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 or preventing these side effects.
6. Blood clots
Although uncommon, Verzenio may cause blood clots. These can be life-threatening if they aren’t treated promptly.
Blood clots can form in different areas of the body, including the legs, thighs, and pelvis (deep vein thrombosis). They can also travel to the lungs (pulmonary embolism). Symptoms of a blood clot include shortness of breath, pain or swelling in your arms or legs, and feeling weak or lightheaded. If you experience any of these symptoms, call 911 or go to the ER immediately.
If you experience blood clots while taking Verzenio, you'll likely need to stop taking it. Your prescriber will determine if it’s safe for you to restart it based on your medical history.
7. Liver problems
Verzenio may raise liver enzyme (protein) levels, which may indicate liver problems. This side effect is typically noticeable about 2 to 6 months after starting Verzenio if it occurs.
Your oncologist should regularly monitor your liver enzyme levels while you’re taking Verzenio. If they become too high, you’ll likely need to stop taking Verzenio or lower your dosage.
Elevated liver enzymes often come with no noticeable symptoms. But you may feel tired, lose your appetite, and/or have pain on the right side of your stomach. You may also bleed or bruise more easily than normal. Let your cancer care 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), while taking Verzenio.
8. Lung problems
Although rare, Verzenio can cause serious lung problems, including interstitial lung disease (ILD).
ILD can become life-threatening, so let your cancer care team know right away if you develop new or worsening breathing problems, a cough, or chest pain while taking Verzenio. You may need to stop taking the medication temporarily or lower your dosage.
Your oncologist will likely check your lung function if you develop symptoms such as shortness of breath, a dry cough, or chest pain while taking Verzenio. If you develop severe ILD, you'll likely need to stop taking Verzenio altogether.
Frequently asked questions
No, weight gain isn’t typical with Verzenio. It's actually more likely that you’ll lose weight while taking Verzenio. This is because it often causes nausea and reduces appetite. Choosing nutrient-dense foods and eating small, frequent meals can help you maintain your weight and get sufficient nutrition while taking Verzenio.
If you’re experiencing severe or prolonged side effects, they’ll likely resolve with a dose reduction or once you stop taking Verzenio. But if you stop taking Verzenio, your cancer may return or worsen. So you shouldn't stop treatment unless your oncologist recommends it.
It can take almost 4 days to clear Verzenio from your system once you stop taking it. But you shouldn’t stop taking Verzenio unless your oncologist recommends it. Talk to your oncologist before making any changes to your cancer treatment plan.
No, weight gain isn’t typical with Verzenio. It's actually more likely that you’ll lose weight while taking Verzenio. This is because it often causes nausea and reduces appetite. Choosing nutrient-dense foods and eating small, frequent meals can help you maintain your weight and get sufficient nutrition while taking Verzenio.
If you’re experiencing severe or prolonged side effects, they’ll likely resolve with a dose reduction or once you stop taking Verzenio. But if you stop taking Verzenio, your cancer may return or worsen. So you shouldn't stop treatment unless your oncologist recommends it.
It can take almost 4 days to clear Verzenio from your system once you stop taking it. But you shouldn’t stop taking Verzenio unless your oncologist recommends it. Talk to your oncologist before making any changes to your cancer treatment plan.
The bottom line
Common Verzenio (abemaciclib) side effects include low blood cell counts, diarrhea, and nausea. Hair loss or thinning is also possible. More serious side effects include infections, liver and lung problems, and blood clots.
Many Verzenio side effects can be managed at home and/or by lowering your dosage. Talk to your oncologist for more information about managing Verzenio side effects.
Why trust our experts?
References
American Cancer Society. (2024). Hair loss (alopecia).
American Cancer Society. (2025). Hormone therapy for breast cancer.
American Lung Association. (n.d.). Interstitial lung disease (ILD).
Eli Lilly and Company. (2025). Verzenio - abemaciclib tablet [package insert].
LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. (2018). Abemaciclib. National Institute of Diabetes and Digestive and Kidney Diseases.
Punnapuzha, S., et al. (2023). Febrile neutropenia. StatPearls.
Wekking, D., et al. (2023). CDK4/6 inhibitors in the treatment of metastatic breast cancer: Focus on toxicity and safety. Seminars in Oncology.
