Tavalisse (fostamatinib) is a brand-name oral tablet that’s prescribed for chronic immune thrombocytopenia in certain adults. As with other drugs, Tavalisse can cause side effects. These include diarrhea and high blood pressure.

Tavalisse can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects reported by people who took Tavalisse in clinical trials:

* For more information about this side effect, see “Side effect specifics” below.

Mild side effects can occur with Tavalisse use. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to Tavalisse’s prescribing information.

Mild side effects that have been reported with Tavalisse include:

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you develop a side effect while taking Tavalisse and want to tell the FDA about it, visit MedWatch.

* An allergic reaction is possible after taking Tavalisse. However, this side effect wasn’t reported in clinical trials. To learn more, see the “Side effect specifics” section below.

Tavalisse may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Tavalisse’s prescribing information.

If you develop serious side effects while taking Tavalisse, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects that have been reported and their symptoms include:

  • Liver problems. Symptoms can include:
  • Neutropenia, which is a low level of neutrophils (a type of white blood cell). This can increase your risk of infection, which can cause symptoms such as:
  • High blood pressure.* (See “Side effect specifics” below)
  • Severe allergic reaction.†

* For more information about this side effect, see “Side effect specifics” below.
† An allergic reaction is possible after taking Tavalisse. However, this side effect wasn’t reported in clinical trials. To learn more, see the “Side effect specifics” section below.

Tavalisse may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

How do side effects of Tavalisse compare with those of Doptelet or Promacta?

Tavalisse, Doptelet (avatrombopag), and Promacta (eltrombopag) are drugs that may be prescribed for low platelet counts. Specifically, these drugs are approved to treat chronic immune thrombocytopenia (ITP).

For this reason, these drugs may cause similar side effects. However, Tavalisse works differently from Doptelet and Promacta. As such, these drugs may also cause different side effects.

For example, all three medications can cause nausea, fatigue, and respiratory infection. Tavalisse and Promacta may also cause diarrhea and liver problems, which aren’t expected with Doptelet.

However, most serious side effects reported with Tavalisse differ from those reported with Doptelet and Promacta. Tavalisse can cause high blood pressure and low white blood cell counts. In contrast, Doptelet and Promacta may cause blood clots.

To learn more about how the side effects of these medications compare, talk with your doctor. They’ll recommend the best treatment option for your condition.

Can Tavalisse cause long-term side effects?

No, Tavalisse isn’t expected to cause long-term side effects. Most side effects of Tavalisse go away over the course of treatment or after you stop taking the drug.

In addition, taking Tavalisse long term isn’t expected to increase your risk of developing side effects. However, some side effects may be more likely if you take a higher dose of the drug.

If you have concerns about long-term side effects with Tavalisse, talk with your doctor.

Learn more about some of the side effects that Tavalisse may cause. To find out how often side effects occurred in clinical trials, see the prescribing information for Tavalisse.

Diarrhea

It’s possible for Tavalisse to cause diarrhea. In clinical trials of the drug, diarrhea was a commonly reported side effect.

Diarrhea with Tavalisse is usually mild. However, in rare cases, it can become severe. Severe diarrhea can cause dehydration, which could lead to kidney problems.

What you can do

If you have diarrhea while taking Tavalisse, be sure to drink plenty of fluids to help prevent dehydration. It may be helpful to drink electrolyte solutions, such as Pedialyte or Gatorade. These help replace fluids and electrolytes that you can lose with diarrhea.

To help reduce diarrhea, your healthcare professional may recommend avoiding foods that are spicy, oily, or high in fiber. They may also suggest eating smaller meals more frequently instead of large meals.

If dietary changes don’t help, ask your doctor or pharmacist whether you should take an over-the-counter treatment for diarrhea, such as Imodium (loperamide).

If your diarrhea persists or worsens, talk with your doctor. They may reduce your Tavalisse dosage, or they may recommend that you stop taking Tavalisse until your diarrhea improves.

High blood pressure

Tavalisse may cause new or worsening high blood pressure. This was a common side effect in Tavalisse’s clinical trials.

High blood pressure caused by Tavalisse is usually mild. However, it can increase your risk of heart attack and stroke. In rare cases, Tavalisse can cause a hypertensive crisis. This is a type of sudden, severe increase in blood pressure. A hypertensive crisis is a medical emergency.

High blood pressure doesn’t usually cause symptoms. However, a sudden and severe increase in blood pressure may cause headache, dizziness, chest pain, shortness of breath, or confusion.

What you can do

Your doctor will likely monitor your blood pressure when you first start taking Tavalisse. In addition, they’ll likely continue checking your blood pressure throughout your treatment.

Your doctor will usually check your blood pressure every 2 weeks until they determine the Tavalisse dosage that’s right for you. Then, they’ll likely check your blood pressure once per month. They may also recommend that you regularly check your blood pressure at home.

If you develop new or worsening high blood pressure during treatment, your doctor may prescribe another medication to help manage it. If you already take blood pressure medication, your doctor may adjust or reduce your dosage of Tavalisse. Or they may prescribe another drug to take with it.

If medication isn’t effective to manage your blood pressure, your doctor may stop prescribing Tavalisse.

During treatment with Tavalisse, call your doctor right away if you have symptoms of very high blood pressure. If your systolic pressure is suddenly higher than 180 or your diastolic pressure is suddenly higher than 120, call 911 or your local emergency number. This could indicate a hypertensive crisis.

Allergic reaction

As with most drugs, Tavalisse can cause an allergic reaction in some people. However, this side effect wasn’t reported in clinical trials.

Symptoms can be mild or serious and can include:

  • skin rash
  • itching
  • flushing
  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What you can do

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep taking Tavalisse. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Be sure to talk with your doctor about your health history before you take Tavalisse. This drug may not be the right treatment for you if you have certain medical conditions or other factors that affect your health. These are considered drug-condition or drug-factor interactions. The conditions and factors to consider include:

High blood pressure. If you have high blood pressure, talk with your doctor before starting treatment with Tavalisse. This drug may cause high blood pressure. If you already have this condition, taking Tavalisse could make it worse. Your doctor will advise whether Tavalisse is safe for your condition.

Liver problems. Tavalisse may cause liver problems. If you have a liver problem, taking this drug could make it worse. Before starting treatment with Tavalisse, tell your doctor about any liver problems you may have. They’ll decide whether this drug is safe for you to take.

Low white blood cell count. It’s possible for Tavalisse to cause neutropenia. This is a low level of white blood cells called neutrophils. If you already have a low white blood cell count, taking Tavalisse could make it worse. Talk with your doctor about whether this medication is right for you.

Allergic reaction. If you’ve had an allergic reaction to Tavalisse or any of its ingredients, your doctor will likely not prescribe Tavalisse. Ask your doctor about other medications that may be better options for you.

Pregnancy or breastfeeding. If you’re pregnant or breastfeeding, Tavalisse is not considered safe for you to take. Before starting treatment with Tavalisse, be sure to tell your doctor if you’re pregnant, breastfeeding, or planning for either. They can tell you about other treatment options for your condition.

Alcohol consumption. If you drink alcohol, it may not be safe for you to drink it during treatment with Tavalisse. This is because Tavalisse and heavy alcohol consumption can both cause liver problems. In turn, these liver problems can affect how well your body processes Tavalisse. If you have questions about drinking alcohol during treatment with Tavalisse, talk with your doctor.

If you’d like to learn more about Tavalisse, talk with your doctor or pharmacist. They can help answer any questions you have about side effects from taking the drug.

Besides talking with your doctor, you can do some research on your own. These articles might help:

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.