Written by Rachel Nall | Published on October 23, 2013
Medically Reviewed by George Krucik, MD, MBA on October 23, 2013

What Is Isentress?

Brand Name: Isentress
Generic Name: Raltegravir

Isentress (pronounced eye sen tris) is a chewable or film-coated tablet used to treat HIV. Doctors often prescribe Isentress along with other HIV medications, especially Truvada. The U.S. Food and Drug Administration has approved Isentress for adults and for children who are least two years old and weigh at least 10 kilograms (approximately 22 pounds).

Read the FDA description of Isentress.

What Does Isentress Do?

Isentress is not a cure for HIV. It helps to reduce the amount of HIV viruses in your body by preventing the virus from being integrated into CD4+ T cells. This effect can improve your immune system, making you less susceptible to harmful infections.

Isentress does not have to be taken with meals.

This information is a summary. Before starting this medication, discuss questions with your healthcare provider and make sure you understand dosage instructions.

What Should I Tell My Doctor Before Starting Isentress?

Tell your doctor before taking Isentress if you:

  • are breastfeeding or planning on breastfeeding, as the medication and HIV virus can be transmitted to the baby
  • have liver problems, such as hepatitis B or C
  • have phenylketonuria, as Isentress tablets contain aspartame
  • are pregnant or are planning on becoming pregnant

Also notify your physician if you have been diagnosed with a muscle disorder such as rhabdomyolysis.

What Medications May Interact with Isentress?

Always tell your physician about any prescription medications or herbal remedies you are taking.

You should not take Isentress and the medication rifampin, also known as Rifadin, Rifamate, Rifater, or Rimactane. Many physicians prescribe this medication to treat tuberculosis.

Also, medications known to cause muscle conditions should be avoided when taking Isentress. These include:

  • fenofibrate (Tricor)
  • gemfibrozil (Lopid)
  • statins (HMG-CoA reductase inhibitors, such as Lipitor, Zocor, and Mevacor)
  • zidovudine (Retrovir)

Possible Side Effects of Isentress

There are some severe and emergent side effects of these medications. Contact your medical provider immediately if you experience:

  • immune system changes that make you feel like you have a viral infection immediately after taking the medication
  • a severe allergic reaction, including swelling in your mouth or face, difficulty breathing, extreme tiredness, joint aches, fever, and generally feeling ill
  • a severe skin reaction that causes blisters or sores in your mouth, peeling skin, or redness or swelling in your eyes
  • symptoms of liver disease, such as yellowing of the skin or whites of the eyes, darkened urine, nausea, vomiting, appetite loss, pale-colored stool, and aching and tenderness just below your ribs on your right side

The following side effects may occur but do not usually represent an emergency. Discuss them with your doctor or healthcare professional if they continue or are bothersome.

These side effects occurred in more than 2 percent of patients studied:

  • difficulty sleeping
  • dizziness
  • headache
  • nausea
  • tiredness

These side effects occurred in less than 2 percent of patients studied:

  • allergic reaction
  • depression
  • genital herpes
  • herpes zoster, including shingles
  • kidney failure
  • kidney stones
  • stomach upset
  • suicidal thoughts
  • vomiting
  • weakness

This list may not describe all possible side effects. Call your doctor or healthcare provider for advice about side effects. You can report side effects to the FDA at 1-800-FDA-1088.

Isentress and Truvada

Isentress and Truvada, a medication used to boost the immune system, are often prescribed together because they reduce side effects when taken together. Combined, the medications do not affect low-density lipoprotein (LDL) or “bad” cholesterol levels as they do when taken alone. Patients often experience fewer side effects, such as difficulty sleeping or headache, when taking Isentress and Truvada.

Isentress and Alcohol

Alcohol is associated with worsening the side effects of Isentress. These include drowsiness or dizziness. Talk to your doctor about drinking alcohol while taking Isentress, and do not operate heavy machinery or a vehicle when combining the two.

Where Should I Keep Isentress?

Both Isentress film-coated tablets and chewable tablets should be stored at room temperature or between 68 and 77 degrees Fahrenheit (20 to 25 degrees Celsius). Chewable tablets must be kept in their original packaging with the drying agent in the bottle to protect the pills from moisture.

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

FDA WARNING: Severe, potentially life-threatening and fatal skin reactions have been reported. This includes cases of Stevens-Johnson syndrome, hypersensitivity reaction and toxic epidermal necrolysis. Immediately discontinue treatment with ISENTRESS and other suspect agents if severe hypersensitivity, severe rash, or rash with systemic symptoms or liver aminotransferase elevations develops and monitor clinical status, including liver aminotransferases closely.
Monitor for Immune Reconstitution Syndrome.
Inform patients with phenylketonuria that the 100 mg and 25 mg chewable tablets contain phenylalanine. 

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Article Sources:

●      How Isentress Works. (July 2013). Merck & Co. Retrieved October 8, 2013, from
●      Patient Information: Isentress. (August 2013). Merck & Co. Retrieved October 8, 2013, from

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