Promacta (eltrombopag) is a prescription drug that’s used to treat certain blood disorders. Promacta can cause side effects that range from mild to serious. Examples include nausea, fatigue (low energy), and cataracts (an eye problem).

Promacta is used in adults and certain children to treat the following conditions in specific situations:

The active ingredient in Promacta is eltrombopag. (An active ingredient is what makes a drug work.)

Promacta comes in two forms:

  • a tablet that you swallow
  • a powder you mix with water to make a liquid suspension that you swallow

Keep reading to learn about the common, mild, and serious side effects Promacta can cause. For a general overview of the drug, including details about its uses, see this article.

Some people may experience mild to serious side effects during their Promacta treatment. Examples of this drug’s commonly reported side effects include:

  • cough
  • fever
  • headache
  • anemia (low level of red blood cells)
  • nausea

Keep reading to learn about other possible mild and serious side effects of Promacta.

Promacta may cause mild side effects for some people. Examples that have been reported with this drug include:

* To learn more about this side effect, see the “Side effects explained” section below.

In most cases, these side effects should be temporary. And some may be easily managed. But if you have symptoms that are ongoing or bother you, talk with your doctor or pharmacist. And do not stop taking Promacta unless your doctor recommends it.

Promacta may cause mild side effects other than those listed above. See the drug’s prescribing information for details.

Although uncommon, serious side effects can happen with Promacta. Serious side effects that have been reported with this drug include:

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.

* To learn more about this side effect, see the “Side effects explained” section below.
† An allergic reaction is possible after taking Promacta, but this side effect wasn’t reported in studies.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Promacta, visit MedWatch.

Get answers to some frequently asked questions about Promacta’s side effects.

Is Promacta safe for older adults?

Yes, Promacta is considered safe for older adults. In studies, people ages 65 years and older generally had the same side effects as younger adults. To learn more about Promacta and possible age-related side effects, talk with your doctor or pharmacist.

Does Promacta cause weight gain?

No, it’s not likely. Weight gain wasn’t reported as a side effect in studies of Promacta. But other treatments for blood disorders may cause this side effect. For example, corticosteroids are known to cause weight gain. Examples include Hemady (dexamethasone) and Rayos (prednisone).

If you’re concerned about weight gain with Promacta or other treatments you may be receiving, talk with your doctor. They can advise you on your risk of this side effect and suggest ways to manage it.

Learn more about some of the side effects Promacta may cause.

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). Liver damage was a rare side effect in studies of Promacta. But in extreme cases, this side effect can be life threatening.

Symptoms of liver damage can include:

What might help

Before starting Promacta, your doctor will give you blood tests to check how well your liver is working. They’ll repeat these tests from time to time during your Promacta treatment. If you have a liver problem before starting this drug, your doctor will determine whether it’s the right treatment option for you.

If you have symptoms of liver damage while taking Promacta, tell your doctor right away. If you’re found to have liver damage, they can determine whether it’s safe for you to keep taking the drug. If you do continue taking it but your liver damage worsens or returns, your doctor may switch you to a different treatment.

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 (long-term) hepatitis C. A boxed warning is the most serious warning from the Food and Drug Administration (FDA).

If you have chronic hepatitis C, taking Promacta with certain hepatitis C treatments may increase your risk of decompensated liver disease. This was a less common side effect in Promacta studies. With this condition, your liver doesn’t work as well as it should. This can lead to ascites (fluid buildup in your abdomen) and encephalopathy (a severe brain condition).

Other symptoms of liver problems include:

What might help

Tell your doctor right away if you have symptoms of liver problems while taking Promacta. If you’re found to have liver problems, they’ll likely stop your Promacta and hepatitis C treatments. They’ll advise you regarding any treatments that are necessary for your liver problems.

Cataracts (an eye problem)

Cataracts were a less common side effect in studies of Promacta. Cataracts are cloudy areas in the lens of your eye. Symptoms may include:

What might help

If you have symptoms of cataracts while taking Promacta, talk with your doctor. They may suggest seeing an eye doctor to check and treat your symptoms. If you have cataracts before starting Promacta or develop them during treatment, your doctor will determine whether it’s safe for you to take this medication.

Hair loss

Hair loss was one of the more common side effects in studies of Promacta. Symptoms can include:

What might help

While taking Promacta, treating your hair gently may help lessen hair loss. This includes avoiding styling tools, such as curling irons and straighteners, and hair treatments, such as hair color or perms.

For tips to help prevent hair loss, see this article. You can also talk with your doctor. They can suggest other ways to help lessen this side effect.

Allergic reaction

Like most drugs, Promacta can cause an allergic reaction in some people, but this side effect wasn’t reported in studies.

Symptoms of an allergic reaction can be mild to serious and can include:

  • skin rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin (usually in your eyelids, lips, hands, or feet)
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms. Examples include:

If your doctor confirms you’ve had a mild allergic reaction to Promacta, they’ll decide whether you should continue taking it.

If you have symptoms of a severe allergic reaction, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you’ve had a serious allergic reaction to Promacta, they may have you switch to a different treatment.

Keeping track of side effects

During your Promacta treatment, consider taking notes on any side effects you’re having. You can then share this information with your doctor. This is especially helpful when you first start taking a new drug or using a combination of treatments.

Your side effect notes can include things such as:

  • what dose of the drug you were taking when you had the side effect
  • how soon you had the side effect after starting that dose
  • what your symptoms were
  • how your symptoms affected your daily activities
  • what other medications you were taking
  • any other information you feel is important

Taking notes and sharing them with your doctor will help them learn more about how Promacta affects you. They can then use this information to adjust your treatment plan if needed.

Promacta may not be suitable for everyone. It comes with several warnings, including boxed warnings.

Boxed warnings

Promacta has boxed warnings about the risk of liver damage and liver problems in people with chronic (long-term) hepatitis C. Boxed warnings are the most serious warnings from the Food and Drug Administration (FDA).

Risk of liver damage. Taking Promacta may cause liver damage. In extreme cases, this side effect can be life threatening.

Risk of liver problems in people with chronic hepatitis C. If you have chronic (long-term) hepatitis C, taking Promacta with certain hepatitis C treatments may increase your risk of decompensated liver disease. This can lead to ascites (fluid buildup in your abdomen) and encephalopathy (a severe brain condition).

To learn more, see the “Side effects explained” section above.

Other warnings

Promacta may not be right for you if you have certain medical conditions. This is known as a drug-condition interaction. Other factors may also affect whether Promacta is a good treatment option for you. Talk with your doctor about your health history before starting this medication. Factors to consider include those described below.

Blood cancer. Doctors typically won’t prescribe Promacta for people with a type of blood cancer called myelodysplastic syndrome (MDS). The drug could increase the risk of MDS becoming another type of blood cancer. Before taking Promacta, tell your doctor if you have MDS. They’ll likely prescribe a treatment other than Promacta for your condition.

Cataracts. Promacta may worsen cataracts in people who already have them. Before starting this drug, tell your doctor if you have cataracts. They may suggest seeing an eye doctor to closely monitor your condition during Promacta treatment.

Conditions that increase the risk of blood clots. Before taking Promacta, tell your doctor if you have a condition that increases your risk of blood clots. For example, tell them if you’ve had blood clots in the past or if you have a genetic (inherited) condition that causes them.

Promacta may cause blood clots as a side effect. And you may be more likely to develop them if you already have a condition that increases this risk. Your doctor can determine whether Promacta is a safe treatment option for you.

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

East or Southeast Asian ancestry. If you’re of East or Southeast Asian ancestry, talk with your doctor before starting treatment with Promacta. People of this ancestry may have a higher risk of side effects from the drug. To reduce this risk, your doctor may give you a lower dosage of Promacta than usual.

Alcohol and Promacta

It’s likely safe to drink alcohol in moderation during Promacta treatment. But keep in mind that drinking large amounts of alcohol may cause liver damage. Promacta may cause liver damage and liver problems in people with chronic (long-term) hepatitis C.* So, taking this drug while drinking large amounts of alcohol could increase your risk of liver problems.

If you drink alcohol, talk with your doctor. They can recommend whether there’s an amount that’s safe to consume while taking Promacta.

* Promacta has a boxed warning for these side effects. This is the most serious warning from the Food and Drug Administration (FDA). To learn more, see the “Side effects explained” section above.

Pregnancy and breastfeeding while taking Promacta

It’s not known whether Promacta is safe to take while pregnant or breastfeeding. It isn’t known whether the drug may harm a fetus or cause side effects in a child who is breastfed. To be safe, your doctor may advise you not to take this drug during pregnancy or while breastfeeding. Talk with them if you have questions. They can discuss with you the risks and benefits of Promacta treatment during these times.

Promacta is used to treat certain blood disorders. Taking the drug may cause mild to serious side effects. If you have questions about side effects Promacta can cause, talk with your doctor or pharmacist. Examples of questions to help get you started include:

  • How do the side effects of Promacta compare with those of other drugs used for my condition?
  • If I have side effects from Promacta, should I stop taking it?
  • Do any medical conditions I have increase my risk of side effects from Promacta?

To learn more about Promacta, see these articles:

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Disclaimer: Healthline 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.