Isentress (raltegravir) is a prescription drug used to treat HIV-1. Isentress can cause side effects that range from mild to serious. Examples include difficulty sleeping and headache.

Specifically, Isentress and Isentress HD (high dose form) are used with other medications as follows:

  • Isentress: to treat HIV-1 in adults and children weighing at least 2 kilograms (kg), which is about 4.4 pounds (lb) (For reference, 1 kg is about 2.2 lb.)
  • Isentress HD: to treat HIV-1 in adults and children weighing at least 40 kg, which is about 88 lb

This article refers to both forms of the drug as Isentress, but it notes any exceptions for Isentress HD.

Isentress is sometimes prescribed off-label for other conditions, such as HIV postexposure prophylaxis (PEP). Off-label use is when doctors prescribe a drug for a purpose other than what it’s approved to treat or help prevent. The U.S. Public Health Service guidelines recommend the use of Isentress with Truvada as a treatment option for PEP.

The active ingredient in Isentress and Isentress HD is raltegravir. Isentress comes as an oral tablet, chewable tablet, and a powder for mixing into a liquid (oral suspension). Isentress HD comes as an oral tablet.

Keep reading to learn about common, mild, and serious side effects that Isentress 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 Isentress treatment. Examples of the drug’s commonly reported side effects include:

The following sections include more side effects of Isentress. Each person’s experience with side effects may differ.

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

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

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

Allergic reaction

For some people, Isentress can cause an allergic reaction. This side effect was reported in the drug’s studies.

In general, symptoms of allergic reaction can be mild or serious.

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. They can also determine whether you should continue Isentress treatment.

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

Your doctor can confirm whether you’ve had a serious allergic reaction to Isentress. If so, they may have you switch to a different treatment.

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

If you develop serious side effects while taking Isentress, 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 call your local emergency number.

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 Isentress, visit MedWatch.

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.

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

What are the Isentress and Truvada side effects when taking them together?

Side effects reported with Truvada (emtricitabine and tenofovir disoproxil fumarate) include:

If you also take both drugs together, you may experience Isentress’s side effects too. Isentress side effects could include those listed above but not usually upper respiratory infection. See the sections above in this article for more details about the common, mild, and serious side effects of Isentress.

You also can learn more about the side effects of taking Isentress with Truvada by speaking with your doctor.

Does Isentress cause long-term side effects?

It’s possible. Long-term side effects include those that may start at any time you’re taking a drug. These are possible even if you’ve taken the drug for a long time. It also includes side effects that may not go away, even after you stop taking the drug.

Examples of long-term side effects reported in Isentress’s studies include:

Talk with your doctor to learn more about possible side effects of Isentress and how long they may last.

How do the Isentress 400-mg side effects compare with those of other dosages?

Compared with other Isentress doses, no additional side effects were reported with the Isentress 400-mg dose.

Talk with your doctor if you have additional questions about side effects of Isentress.

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

Severe skin reaction

Severe skin reaction was a rare side effect reported in studies of Isentress. Examples of these skin reactions include Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). SJS and TEN may cause symptoms such as:

  • skin rash
  • blisters or peeling skin
  • sore throat
  • red eyes (whites of the eyes or eyelids)
  • feeling ill
  • muscle or joint aches
  • fever

What might help

If you experience any of the above severe skin reaction symptoms, call 911 or your local emergency number. Both SJS and TEN can be life threatening.

Be sure to tell your doctor if you develop these skin reactions while taking Isentress. They’ll likely stop your Isentress treatment and recommend another medication to manage your HIV.

Immune system changes

Your immune system may change when you take Isentress. This side effect was reported with use of combination HIV-1 medications, including Isentress. Specifically, your immune system may begin changing by getting stronger. Then it starts fighting previous infections that have been hidden in your body for a long time.

These previous infections can include pneumonia and tuberculosis. Symptoms that may occur include:

What might help

If you develop any of the above symptoms during your Isentress treatment, talk with your doctor right away. They can help treat the infection.

Keeping track of side effects

During your Isentress 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

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

Below is important information you should consider before taking Isentress.

Warnings

Isentress 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 Isentress is a good treatment option for you.

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

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.