Harvoni (ledipasvir/sofosbuvir) is a prescription drug used to treat hepatitis C in adults and certain children. Harvoni can cause side effects that range from mild to serious. Examples include weakness, headache, and diarrhea.

The active ingredients in Harvoni are ledipasvir and sofosbuvir. (An active ingredient is what makes a drug work.) The drug comes as oral tablets and oral pellets.*

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

* The oral pellets can be swallowed alone or mixed with certain foods before swallowing.

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

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

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

Mild side effects have been reported with Harvoni. These include:

In most cases, these side effects should be temporary. And some may be easily managed. You may have an increased risk of side effects if you have cirrhosis.

If you have symptoms that are ongoing or bothersome, talk with your doctor or pharmacist. And do not stop taking Harvoni unless your doctor recommends it.

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

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

Serious side effects have been reported with Harvoni. These include:

If you develop serious side effects while taking Harvoni, 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 Harvoni, but this side effect wasn’t reported in studies.

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

Does Harvoni cause long-term side effects?

It’s unlikely. Long-term side effects weren’t reported in studies of Harvoni.

If you’re concerned about possible long-term side effects from this medication, talk with your doctor or pharmacist.

How do side effects of Harvoni compare with those of Epclusa?

Most of Harvoni’s side effects are similar to those of Epclusa (velpatasvir/sofosbuvir).

For example, both Harvoni and Epclusa may cause mild side effects such as headache, nausea, and fatigue. And both drugs have a boxed warning for the risk of hepatitis B reactivation in certain people. A boxed warning is the most serious warning from the FDA. For details, see the “Side effects explained” section below.

For lists of possible side effects of Harvoni, see the sections above. To learn more about Epclusa’s side effects, see this article. You can also talk with your doctor or pharmacist.

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

Risk of hepatitis B reactivation in certain people

Harvoni has a boxed warning about the risk of hepatitis B reactivation in certain people. A boxed warning is the most serious warning from the FDA. It alerts doctors and patients about drug effects that may be dangerous.

With reactivation, the hepatitis B virus (HBV) becomes active and causes symptoms of a hepatitis B infection. This side effect can happen while you’re taking Harvoni or after you’ve stopped the drug. In extreme cases, hepatitis B reactivation may lead to liver failure or be life threatening.

Hepatitis B reactivation wasn’t reported in studies of Harvoni. But it’s a known risk of hepatitis C treatments, including Harvoni, in people who have HBV or had it in the past. Hepatitis B infection may cause symptoms such as:

What might help

Before you start Harvoni treatment, your doctor will order a blood test to check for HBV. If the test shows HBV, they’ll watch closely for symptoms of hepatitis B infection during and after your Harvoni treatment.

If you have symptoms of hepatitis B infection, tell your doctor right away. They’ll order tests to check for HBV and prescribe treatments if needed.

Diarrhea

Compared to fatigue and headache, diarrhea was a less common side effect reported in studies of Harvoni. Diarrhea may cause symptoms such as:

  • watery, loose stool
  • frequent urges to have a bowel movement
  • abdominal bloating, cramping, or pain

What might help

If you have diarrhea during Harvoni treatment, talk with your doctor. They can recommend over-the-counter options to help relieve your symptoms. An example is Imodium (loperamide).

Your Harvoni dosage can be taken with or without food. But taking your dosage with food could help prevent or ease diarrhea. Be sure to take Harvoni exactly as your doctor prescribes it.

Allergic reaction

Like most drugs, Harvoni can cause an allergic reaction in some people. But this side effect wasn’t reported in studies. Symptoms 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:

  • an oral antihistamine, such as Benadryl (diphenhydramine)
  • a product you apply to your skin, such as hydrocortisone cream

If your doctor confirms you’ve had a mild allergic reaction to Harvoni, they’ll decide if 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 Harvoni, they may have you switch to a different treatment.

Keeping track of side effects

During your Harvoni 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

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

Below is important information you should consider before taking Harvoni.

Boxed warning: Risk of hepatitis B reactivation in certain people

Harvoni has a boxed warning for the risk of hepatitis B reactivation in certain people. A boxed warning is the most serious warning from the FDA.

With reactivation, HBV becomes active and causes symptoms of a hepatitis B infection. This risk affects people taking Harvoni for hepatitis C who have HBV or had it in the past.

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

Other warnings

Harvoni can sometimes cause harmful effects in people who have certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether Harvoni is a good treatment option for you.

Talk with your doctor about your health history before starting this medication. Be sure to tell them if any of the following factors apply to you:

Alcohol and Harvoni

There are no known interactions between alcohol and Harvoni. However, drinking alcohol may worsen certain side effects of the drug, such as nausea, headache, and dizziness.

Keep in mind that Harvoni is used to treat hepatitis C (inflammation of your liver). Consuming large amounts of alcohol may also lead to liver problems that worsen this condition.

If you have questions about consuming alcohol during Harvoni treatment, talk with your doctor or pharmacist.

Pregnancy and breastfeeding with Harvoni

There is limited information about the safety of taking Harvoni during pregnancy.

Pregnancy

It’s not known whether it’s safe to take Harvoni during pregnancy. If you’re pregnant or planning to become pregnant, talk with your doctor before starting treatment with Harvoni.

Breastfeeding

It isn’t known whether Harvoni is safe to take while breastfeeding. If you’re breastfeeding or planning to do so, talk with your doctor before starting this medication.

Like most drugs, Harvoni can cause a number of side effects that range from mild to serious. But most are temporary and go away after a few days to weeks. If you have questions about side effects that Harvoni can cause, talk with your doctor. Examples of questions to help get you started include:

  • Do any of the medications I take increase my risk of side effects from Harvoni?
  • Does my risk of diarrhea depend on the Harvoni dosage I take?
  • Are there any side effects of Harvoni I should tell you about right away?

To learn more about Harvoni, 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.