Biktarvy (bictegravir/emtricitabine/tenofovir alafenamide) is a prescription drug that’s used to treat HIV in adults and some children. Biktarvy can cause side effects that range from mild to serious. Examples include fatigue and skin rash.

Some people may experience mild to serious side effects during treatment with Biktarvy. Listed below are some examples of the drug’s commonly reported side effects. But these are not all the possible side effects of Biktarvy.

Some common side effects include:

  • nausea
  • diarrhea
  • headache
  • fatigue (low energy)

These are just a few of the more common side effects reported by people in studies of Biktarvy.

Biktarvy may cause some mild side effects.

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 Biktarvy unless your doctor recommends it.

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

Biktarvy may cause serious side effects, but they’re usually less common than mild ones.

Serious side effects that have been reported with Biktarvy include:

If you develop serious side effects while taking Biktarvy, 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, see the “Side effects explained” section below.
† Biktarvy has a boxed warning for this side effect. This is the most serious warning from the Food and Drug Administration (FDA). To learn more, 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 Biktarvy, visit MedWatch.

Allergic reaction

For some people, Biktarvy can cause an allergic reaction.

But this side effect wasn’t reported in the drug’s studies.

In general, symptoms of allergic reaction can be mild or serious. You can learn more about possible symptoms in this article.

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 and can determine whether you should keep taking Biktarvy.

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 Biktarvy, they may have you switch to a different treatment.

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

Does Biktarvy cause weight gain?

It’s possible. Weight gain wasn’t reported in studies of Biktarvy, but it has been reported since Biktarvy and similar drugs were approved for use. Biktarvy contains the active ingredients bictegravir (BIC), emtricitabine (FTC), and tenofovir alafenamide (TAF).

BIC belongs to a group of drugs called integrase strand transfer inhibitors (INSTIs). FTC and TAF belong to a group of drugs called nucleoside reverse transcriptase inhibitors (NRTIs).

It’s possible for both INSTIs and NRTIs to cause weight gain in some cases.

If you experience weight gain during treatment with Biktarvy, talk with your doctor. They’ll help determine whether Biktarvy is the cause. They can also suggest ways to manage your weight while taking this drug.

Are there any long-term side effects of Biktarvy?

Yes. Biktarvy may cause long-term side effects, but they’re not common.

Long-term side effects include:

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

Long-term side effects may begin during treatment with Biktarvy. And in some cases, they may continue after treatment ends.

If you have ongoing side effects while taking Biktarvy, talk with your doctor. They’ll determine whether you need to stop taking it and switch to a different HIV medication instead.

Do not stop taking Biktarvy without first talking with your doctor. Suddenly stopping this drug can cause serious side effects if you have certain conditions. (See “Side effects explained” below for more information.)

Your doctor will monitor you for worsening of certain conditions if you stop taking Biktarvy.

Does Biktarvy cause neuropathy?

No, neuropathy (nerve damage) wasn’t reported in studies of the drug. Some symptoms of neuropathy include:

  • tingling in the hands or feet
  • trouble walking (balance or coordination problems)
  • muscle cramps
  • painful burning sensations in your hands or feet

If you experience symptoms of neuropathy, talk with your doctor. They’ll discuss possible causes with you and suggest ways to help manage your symptoms.

Will I have hair loss from Biktarvy?

No, this wasn’t a side effect reported in studies of the drug.

But Biktarvy contains the active ingredients emtricitabine and tenofovir alafenamide. These belong to a group of drugs called NRTIs. And there have been reports of hair loss with NRTIs.

If you have hair loss while taking Biktarvy, talk with your doctor. They’ll suggest ways to help manage this side effect.

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

Risk of worsening hepatitis B

Biktarvy has a boxed warning for the risk of worsening hepatitis B. A boxed warning is the most serious warning from the Food and Drug Administration (FDA).

Biktarvy may lead to a worsening of hepatitis B in some people. You have an increased risk of worsening hepatitis B infection if you also have HIV and stop taking Biktarvy.

If you have both conditions, your doctor will monitor your liver function for several months if you stop taking Biktarvy. This is to make sure the hepatitis B infection isn’t becoming worse. If it is, you may need treatment for it.

For more details on this serious side effect, see the prescribing information or talk with your doctor or pharmacist.

What might help

Your doctor will check whether you have hepatitis B infection before you begin treatment with Biktarvy. Do not suddenly stop taking Biktarvy if you have both HIV and hepatitis B. This could increase your risk of serious liver damage from worsening hepatitis B.

If you have both infections and need to stop taking Biktarvy, your doctor will monitor your liver function for several months after you stop treatment. This is to make sure the hepatitis B infection isn’t worsening.

You may need treatment for hepatitis B infection if your condition worsens after you stop Biktarvy.

Skin rash

Biktarvy may cause a skin rash in some people. But this wasn’t very common in the drug’s studies.

What might help

If you develop a rash while taking Biktarvy, tell your doctor. If it’s a mild rash, they may recommend an antihistamine such as diphenhydramine (Benadryl). They may also recommend hydrocortisone cream, which you apply to the affected areas of your skin.

But if you have a severe rash, this may be a sign of an allergic reaction to Biktarvy. You should call 911 or go to an emergency medical center immediately if you have this or other symptoms of a severe allergic reaction. These include trouble breathing and swelling under your skin or in your mouth or throat. (See “Allergic reaction” above for more information.)

New or worsening kidney problems

Biktarvy can cause new or worsening kidney problems, including kidney failure in some people. Taking certain other drugs that also affect your kidneys may increase your risk of kidney problems from Biktarvy. Tell your doctor about all the medications you take and whether you have a history of kidney disease.

Symptoms of kidney problems include issues with urination, such as:

What might help

Your doctor will check your kidney function before you start Biktarvy and will monitor it throughout your treatment. If you develop signs of kidney problems, they’ll determine whether this drug is right for you based on the severity of your symptoms. In some cases, they’ll have you stop Biktarvy and will recommend an alternative that’s safer for you.

Lactic acidosis

Biktarvy may cause a serious reaction known as lactic acidosis. This is when your body has too much lactic acid and can’t get rid of it. This can be life threatening in certain cases.

Symptoms of lactic acidosis include:

What might help

Tell your doctor if you have liver or kidney problems. These organs remove Biktarvy from your body. If they’re not functioning properly, lactic acid can build up in your system. This can increase your risk of developing lactic acidosis.

Your doctor will monitor your liver and kidney function before you start Biktarvy and during your treatment. But if you experience symptoms of lactic acidosis, call 911 or your local emergency number immediately.

Keeping track of side effects

During your Biktarvy 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 new drugs 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 it 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 Biktarvy affects you. They can then use this information to adjust your treatment plan if needed.

Below are several warnings about Biktarvy. This drug may not be suitable for you in certain situations. Your doctor will determine whether it’s the right treatment option for you based on your health.

Boxed warning: Risk of worsening hepatitis B

Biktarvy has a boxed warning for the risk of worsening hepatitis B. A boxed warning is the most serious warning from the Food and Drug Administration (FDA).

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

Other warnings

Biktarvy 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 Biktarvy is a good treatment option for you.

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

  • liver problems
  • kidney problems
  • depression or certain mental health conditions
  • alcohol consumption
  • previous allergic reaction to Biktarvy
  • pregnancy
  • breastfeeding

Help is out there

If you or someone you know is in crisis and considering suicide or self-harm, please seek support:

If you’re calling on behalf of someone else, stay with them until help arrives. You may remove weapons or substances that can cause harm if you can do so safely.

If you are not in the same household, stay on the phone with them until help arrives.

Biktarvy is a prescription drug used to treat HIV. It can cause mild to serious side effects. Reactions to this drug can vary depending on your age, other medical conditions you may have, and other medications you take.

If you have questions about side effects from Biktarvy, ask your doctor for more information. Here are some questions to get you started:

  • Is my risk of side effects from Biktarvy higher when I first start treatment?
  • At what point should I call my doctor about any side effects I experience?
  • Will taking Biktarvy with a vitamin increase my risk of side effects?

To learn more about Biktarvy, 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.