An Overview of Prezcobix (Darunavir/Cobicistat)

Brand Name: Prezcobix
Other Names: DRV/COBI, darunavir ethanolate/cobicistat
Drug Class: Combination Drugs


Prezcobix pill

Prezcobix can cause serious, life-threatening side effects. These include liver problems, severe skin reactions or rash, and kidney problems.

Some people taking Prezcobix have had liver problems. People who have chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infection have an increased chance of developing liver problems while taking Prezcobix. Liver function tests may be done before and during treatment with Prezcobix.

Contact your health care provider right away if you have any of the following symptoms that could be signs of liver problems:

  • Dark-colored urine
  • Nausea
  • Vomiting
  • Pale-colored bowel movements
  • Yellowing of your skin or whites of your eyes (jaundice)
  • Pain or tenderness on your right side below your ribs
  • Loss of appetite

Contact your health care provider right away if you have any of the following symptoms that could be signs of severe skin reactions or rash:

  • Fever
  • Tiredness
  • Muscle or joint pain
  • Mouth sores or ulcers
  • Conjunctivitis (redness or swelling of the eyes)
  • Blisters or skin lesions

When taken with certain other medicines, Prezcobix can cause new or worse kidney problems, including kidney failure. Your health care provider should check your kidneys before you start taking Prezcobix and while you are taking Prezcobix.

While taking Prezcobix, it is important to keep all of your appointments with your health care provider.

What Is Prezcobix?

Prezcobix is a prescription medicine approved by the U.S. Food and Drug Administration (FDA) for the treatment of HIV infection in adults. Prezcobix can be taken by adults who have never taken HIV medicines before (called treatment-naive) and adults who have taken HIV medicines before (called treatment-experienced), as long as they have no drug resistance mutations associated with the HIV medicine darunavir (brand name: Prezista). (Drug resistance mutations are changes in the genetic material of HIV that cause the virus to become insensitive to certain HIV medicines.) Talk to your health care provider if you have taken darunavir in the past or are currently taking darunavir. Prezcobix is always used in combination with other HIV medicines.

Prezcobix contains the following two different medicines combined in one pill:

  • Darunavir -- an HIV medicine called a protease inhibitor (PI).
  • Cobicistat -- an HIV medicine called a pharmacokinetic enhancer (CYP3A inhibitor).

Darunavir belongs to a class (group) of HIV drugs called protease inhibitors (PIs). PIs block an HIV enzyme called protease. (An enzyme is a protein that starts or increases the speed of a chemical reaction.) By blocking protease, PIs prevent HIV from multiplying and can reduce the amount of HIV in the body. Pharmacokinetic enhancers, such as cobicistat, are used in HIV treatment to increase the effectiveness of other HIV medicines. In Prezcobix, cobicistat increases the effectiveness of darunavir.

HIV medicines can't cure HIV/AIDS, but taking a combination of HIV medicines (called an HIV regimen) every day helps people with HIV live longer, healthier lives. HIV medicines also reduce the risk of HIV transmission.

What Should I Tell My Health Care Provider Before Taking Prezcobix?

Before taking Prezcobix, tell your health care provider:

  • If you are allergic to any of the HIV medicines in Prezcobix (cobicistat or darunavir) or any other medicines.
  • If you have liver problems, including hepatitis B virus (HBV) infection or hepatitis C virus (HCV) infection.
  • If you have kidney problems.
  • If you are allergic to sulfa (sulfonamide).
  • If you have diabetes.
  • If you have hemophilia.
  • If you have any other medical conditions.
  • If you are pregnant or plan to become pregnant. Prezcobix should not be used during pregnancy because you may not have enough Prezcobix in your body during pregnancy. Tell your health care provider if you become pregnant while taking Prezcobix. Your health care provider may prescribe different medicines if you become pregnant while taking Prezcobix.
  • If you are breastfeeding or plan to breastfeed. Do not breastfeed if you are infected with HIV or are taking Prezcobix.
  • If you are using hormone-based birth control (such as pills, implants, or vaginal rings). When taking Prezcobix, additional or alternative (non-hormonal) forms of birth control should be used. Your health care provider can help you decide how to adjust your birth control while you are taking Prezcobix. For more information about using birth control and HIV medicines at the same time, view the AIDSinfo HIV and Birth Control infographic.
  • About other prescription and nonprescription medicines, vitamins, nutritional supplements, and herbal products (particularly St. John's wort) you are taking or plan to take. Prezcobix may affect the way other medicines or products work, and other medicines or products may affect how Prezcobix works. Taking Prezcobix together with certain medicines or products may cause serious, life-threatening side effects.

How Should I Take Prezcobix?

Prezcobix comes in tablet form. Each tablet contains:

  • 800 mg darunavir (brand name: Prezista).
  • 150 mg cobicistat (brand name: Tybost).

Take Prezcobix according to your health care provider's instructions.

Take Prezcobix once a day with food.

Always take Prezcobix in combination with other HIV medicines.

If you take too much Prezcobix, contact your health care provider or local poison control center (1-800-222-1222) right away, or go to the nearest hospital emergency room.

For more information on how to take Prezcobix, see the FDA drug label from DailyMed. (DailyMed is a federal website that includes the most recent drug labels submitted to FDA.)

What Should I Do if I Forget a Dose?

If you miss a dose of Prezcobix, take the missed dose as soon as you remember it. But if it is almost time for your next dose, skip the missed dose and just take your next dose at the regular time. Do not take two doses at the same time to make up for a missed dose.

What Side Effects Can Prezcobix Cause?

Prezcobix may cause side effects. Many side effects from HIV medicines, such as nausea or occasional dizziness, are manageable. See the AIDSinfo fact sheet on HIV Medicines and Side Effects for more information.

Some side effects of Prezcobix can be serious. Serious side effects of Prezcobix include liver problems, severe skin reactions or rash, and kidney problems. (See the WARNING box above.)

Other possible side effects of Prezcobix include:

  • Diabetes and high blood sugar (hyperglycemia).
  • Changes in body fat (including gain or loss of fat).
  • Changes in the immune system (called immune reconstitution inflammatory syndrome or IRIS). IRIS is a condition that sometimes occurs when the immune system begins to recover after treatment with an HIV medicine. As the immune system gets stronger, it may have an increased response to a previously hidden infection.
  • Increased bleeding in people with hemophilia.

Tell your health care provider if you have any side effect that bothers you or that does not go away.

These are not all the possible side effects of Prezcobix. To learn more about possible side effects of Prezcobix, read the drug label or package insert or talk to your health care provider or pharmacist.

You can report side effects to FDA at 1-800-FDA-1088 (1-800-332-1088) or online at

How Should Prezcobix Be Stored?

  • Store Prezcobix at room temperature, 68°F to 77°F (20°C to 25°C).
  • Do not use Prezcobix if the original seal over the container opening is broken or missing.
  • Throw away Prezcobix that is no longer needed or expired (out of date). Follow FDA guidelines on how to safely dispose of unused medicine.
  • Keep Prezcobix and all medicines out of reach of children.

Where Can I Find More Information About Prezcobix?

More information about Prezcobix is available:

  • The Prezcobix drug label, from DailyMed. The Patient Counseling Information section of the label includes information for people taking Prezcobix.
  • Prezcobix-related research studies, from the AIDSinfo database of study summaries.
  • A list of FDA-approved HIV medicines, from AIDSinfo.

Manufacturer Information

Janssen Pharmaceuticals, Inc.

The above Patient Version drug summary is based on the following FDA label(s): Tablet, film coated.

[Note from This article was created by AIDSinfo, who last updated it on June 6, 2018. We have cross-posted it with their permission.]