Promacta (eltrombopag) is a brand-name drug that’s prescribed for certain blood disorders in adults and certain children. As with other drugs, Promacta can cause side effects. These include cataracts and digestive problems.

Promacta 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 Promacta in clinical trials:

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

Mild side effects that have been reported with Promacta 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 side effects of the medication. If you develop a side effect while taking Promacta and want to tell the FDA about it, visit MedWatch.

* An allergic reaction is possible after taking Promacta. However, it’s not clear whether this side effect occurred in clinical trials. To learn more, see the “Side effect specifics” section below.

Promacta 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 Promacta’s prescribing information.

If you develop serious side effects while taking Promacta, 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:

* Promacta has a boxed warning for this side effect. A boxed warning is the most serious warning from the Food and Drug Administration (FDA). To learn more, see the “Side effect specifics” section below.
† An allergic reaction is possible after taking Promacta. However, it’s not clear whether this side effect occurred in clinical trials. To learn more, see the “Side effect specifics” section below.

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

Does Promacta cause long-term side effects?

It’s rare but possible. Promacta may cause side effects that start during treatment and lead to long-term problems even after treatment ends.

For example, Promacta may cause cataracts and high platelet levels, which may increase the risk of blood clots.

It may also increase your risk of liver damage* and certain other liver problems if you have chronic hepatitis C.*

If you have questions about Promacta’s long-term side effects, talk with your doctor or pharmacist.

* Promacta has a boxed warning for this side effect. A boxed warning is the most serious warning from the Food and Drug Administration (FDA). To learn more, see the “Side effect specifics” section below.

Is weight gain a side effect of Promacta?

Not directly. Weight gain wasn’t reported in Promacta’s clinical trials.

However, Promacta may cause swelling in your hands or feet. In turn, this could lead to temporary weight gain.

If you have concerns about weight gain with Promacta, talk with your doctor. They can suggest ways to maintain a weight that’s healthy for you.

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

Risk of liver problems in people with chronic hepatitis C

Promacta has a boxed warning for the risk of liver problems in people with chronic hepatitis C. A boxed warning is the most serious warning from the Food and Drug Administration (FDA). It lets doctors and patients know about a drug’s effects that may be dangerous.

People who take Promacta with certain hepatitis C treatments may have an increased risk of decompensated liver disease. This side effect was less common in clinical trials for Promacta.

With decompensated liver disease, your liver doesn’t function as well as it should. This can lead to encephalopathy (a decline in brain function) and ascites (excess fluid in your abdomen).

Other symptoms of liver problems can include:

What you can do

If you have symptoms of liver problems while taking Promacta, tell your doctor right away. They may recommend you stop taking Promacta or your hepatitis C treatments. Your doctor can also advise whether any treatment is necessary for your liver problem.

Risk of liver damage

Promacta has a boxed warning for the risk of liver damage. A boxed warning is the most serious warning from the Food and Drug Administration (FDA). It lets doctors and patients know about a drug’s effects that may be dangerous.

Taking Promacta may cause liver damage. This side effect was rare in clinical trials of the drug. However, increased liver enzyme levels were common. In rare cases, this may be a symptom of liver damage.

Other symptoms of liver damage can include:

  • dark urine
  • jaundice
  • right upper abdominal pain
  • fatigue

What you can do

Before starting Promacta treatment, your doctor will give you blood tests to check how well your liver is working. They’ll monitor your liver function regularly throughout treatment.

If you have liver damage before starting Promacta treatment, your doctor will advise whether this drug is right for you.

If you have symptoms of liver damage while taking Promacta, tell your doctor right away. They can advise whether it’s safe for you to continue taking the drug. If your liver damage persists or worsens during treatment, your doctor may recommend another treatment for your condition.

Allergic reaction

As with most drugs, Promacta can cause an allergic reaction in some people. However, it’s not clear whether these reactions occurred 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 Promacta. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Keep reading to learn more about precautions for Promacta.

Boxed warnings

This drug has boxed warnings about the risk of liver problems in people with chronic hepatitis C and the risk of liver damage. Boxed warnings are the most serious warnings from the Food and Drug Administration (FDA). For details, see the “Side effect specifics” section above.

Other precautions

Be sure to talk with your doctor about your health history before you take Promacta. 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:

Blood cancer, including myelodysplastic syndrome. Before taking Promacta, tell your doctor if you have a blood cancer, including a type of blood cancer called myelodysplastic syndrome (MDS). Doctors typically won’t prescribe Promacta if you have MDS. Taking Promacta could increase the risk of MDS becoming another type of blood cancer called acute myeloid leukemia. Your doctor will likely prescribe a treatment other than Promacta if you have MDS.

Cataracts. If you have cataracts, tell your doctor before starting Promacta treatment. Taking Promacta may worsen symptoms of this eye problem. Before starting Promacta treatment, tell your doctor if you have cataracts. They may refer you to an eye doctor to monitor your condition while you’re taking the drug.

Conditions that increase the risk of blood clots. Before starting Promacta treatment, tell your doctor if you have a condition that increases your risk of blood clots. This may include certain genetic conditions or a history of blood clots.

Promacta may increase platelet levels, which could lead to blood clots. You may be more likely to develop a blood clot if you already have a condition that increases this risk. Your doctor can advise whether Promacta is a safe treatment option.

Southeast or East Asian Ancestry. People of Southeast or East Asian ancestry may have a higher risk of side effects from Promacta. If you’re of Southeast or East Asian descent, your doctor may prescribe a lower dosage of Promacta to reduce your risk of side effects. For more information about Promacta’s dosage, see this article.

Pregnancy or breastfeeding. If you’re pregnant or breastfeeding your child, Promacta may not be safe for you to take. It’s unknown how the drug may affect a fetus or a child who’s breastfed. For this reason, your doctor may not prescribe Promacta while you’re pregnant or breastfeeding. If you can become pregnant, they’ll likely suggest using birth control during treatment and for 7 days after your last dose.

If you’re pregnant, breastfeeding, or planning for either, talk with your doctor. They can advise whether Promacta is safe for you.

Alcohol consumption. If you drink alcohol, Promacta may not be safe for you to take. Over time, heavy alcohol consumption can cause liver problems. Promacta has boxed warnings for the risk of certain liver problems, including decompensated liver disease. Drinking alcohol in excessive amounts during Promacta treatment may increase your risk of liver-related side effects.

If you have questions about drinking alcohol while taking Promacta, talk with your doctor or pharmacist. For more information about Promacta’s boxed warnings, see the “Side effect specifics” section above.

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

As with other drugs, Promacta can cause side effects. Most are mild and should ease over time.

If you’d like to learn more about Promacta, 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:

  • More information about Promacta. For details about other aspects of Promacta, refer to this article.
  • Drug comparison. To learn how Promacta compares with dexamethasone, read this article.
  • Dosage. For information about the dosage of Promacta, view this article.
  • A look at your condition. To learn more about thrombocytopenia (low platelet levels), read this article. For details about blood disorders, see our list of blood and hematology articles.

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.