Drug information

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Brand Name
Lexiva
Other Names
FOS-APV, FPV, fosamprenavir calcium
Drug Class
Protease Inhibitors (PIs)
Drug Image(s): (Click to enlarge)
What are the most important things to know about fosamprenavir? What are the most important things to know about fosamprenavir?

What are the most important things to know about fosamprenavir?

Fosamprenavir can cause serious, life-threatening side effects. These include severe skin rash and allergic reactions, liver problems, and drug interactions.

Contact your health care provider right away if you develop a rash while taking fosamprenavir. Stop taking fosamprenavir and get medical help right away if you develop a rash with any of the following symptoms:

  • General ill feeling
  • Extreme tiredness
  • Muscle or joint aches
  • Fever
  • Blistering or peeling skin
  • Blisters or sores in your mouth
  • Redness or swelling of the eyes (conjunctivitis)
  • Swelling of your face, eyes, lips, tongue, or throat
  • Trouble breathing or swallowing

Some people taking fosamprenavir may develop liver problems. People with a history of hepatitis B virus infection (HBV) or hepatitis C virus infection (HCV) or who have elevated results on liver function tests may have an increased chance of developing new or worsening liver problems while taking fosamprenavir.

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

  • Yellowing of your skin or the whites of your eyes (jaundice)
  • Dark-colored urine
  • Light-colored bowel movements
  • Loss of appetite for several days or longer
  • Nausea or vomiting
  • Pain, aching, or tenderness on the right side of your stomach/abdominal area
  • Itching

Taking fosamprenavir with certain other medicines may result in serious, life-threatening side effects. Tell your health care provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

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

What is fosamprenavir?What is fosamprenavir?

What is fosamprenavir?

Fosamprenavir (brand name: Lexiva) is a prescription medicine approved by the U.S. Food and Drug Administration (FDA) for the treatment of HIV infection in adults and children. Fosamprenavir is always used in combination with other HIV medicines.

For more information on the use of fosamprenavir in people with HIV, please refer to the Guidelines for the Use of Antiretroviral Agents in Adults and Adolescents Living with HIV and the Guidelines for the Use of Antiretroviral Agents in Pediatric HIV Infection.

HIV medicines cannot cure HIV/AIDS, but taking HIV medicines every day helps people with HIV live longer, healthier lives. HIV medicines also reduce the risk of HIV transmission. If you are taking HIV medicines, do not cut down on, skip, or stop taking them unless your health care provider tells you to.

What should I tell my health care provider before taking fosamprenavir?What should I tell my health care provider before taking fosamprenavir?

What should I tell my health care provider before taking fosamprenavir?

Before taking fosamprenavir, tell your health care provider:

  • If you are allergic to fosamprenavir, amprenavir, sulfonamide (sulfa) medicines, or any other medicines.
  • If you have or have had liver problems, including hepatitis B virus infection (HBV) or hepatitis C virus infection (HCV).
  • If you have kidney problems.
  • If you have diabetes or high blood sugar (hyperglycemia).
  • If you have hemophilia.
  • If you have high triglycerides or cholesterol.
  • If you have any other medical conditions.
  • If you are pregnant or plan to become pregnant. Talk to your health care provider about the risks and benefits of taking fosamprenavir during pregnancy. For more information on the use of fosamprenavir during pregnancy, please refer to the Recommendations for the Use of Antiretroviral Drugs During Pregnancy and Interventions to Reduce Perinatal HIV Transmission in the United States.
  • If you are breastfeeding or plan to breastfeed. For women with HIV in the United States, the Guideline does not recommend breastfeeding. Before your baby is born, or if you are already breastfeeding, talk to your health care provider to discuss alternative options for feeding your baby.
  • If you are using hormone-based birth control (such as pills, implants, or vaginal rings). Fosamprenavir may make these forms of birth control less effective. Your health care provider can help you decide how to adjust your birth control while you are taking fosamprenavir. For more information about using birth control and HIV medicines at the same time, view the HIVinfo HIV and Birth Control infographic.
  • About other prescription and nonprescription medicines, vitamins, nutritional supplements, and herbal products (including St. John’s wort) you are taking or plan to take. Fosamprenavir may affect the way other medicines or products work, and other medicines or products may affect how fosamprenavir works. Taking fosamprenavir together with certain medicines or products may cause serious, life-threatening side effects.
How should I take fosamprenavir?How should I take fosamprenavir?

How should I take fosamprenavir?

Fosamprenavir comes in the following forms and strengths:

  • 700-mg tablets
  • 50-mg/mL oral suspension

Take fosamprenavir according to your health care provider’s instructions. Do not miss a dose of fosamprenavir, and do not change your dose or stop taking fosamprenavir without first talking with your health care provider.

Take fosamprenavir tablets by mouth with or without food.

Adults should take fosamprenavir oral suspension without food. Children should take the oral suspension with food. Shake fosamprenavir oral suspension well before each use. If your child vomits within 30 minutes after taking a dose of fosamprenavir, repeat the dose.

Always take fosamprenavir in combination with other HIV medicines.

If you have taken too much fosamprenavir, 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 fosamprenavir, see the FDA drug label.

What should I do if I forget a dose?What should I do if I forget a dose?

What should I do if I forget a dose?

If you miss a dose of fosamprenavir, 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 fosamprenavir cause?What side effects can fosamprenavir cause?

What side effects can fosamprenavir cause?

Fosamprenavir may cause side effects. Some side effects of fosamprenavir can be serious as noted above. Many side effects from HIV medicines, such as nausea or occasional dizziness, are manageable. See the HIVinfo fact sheet on HIV Medicines and Side Effects for more information.

Other possible side effects of fosamprenavir include:
  • Diabetes and high blood sugar (hyperglycemia).
  • Changes in your 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.
  • Increase in body fat (seen in some people taking protease inhibitors).
  • Changes in blood test results. These include increases seen in liver function levels, blood fat levels (cholesterol and triglycerides), and decreases in red blood cells.
  • Increased bleeding in some people with hemophilia.
  • Kidney stones. Contact your health care provider right away if you have pain in your side, blood in your urine, or pain when you urinate.

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 fosamprenavir. To learn more about possible side effects of fosamprenavir, 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.

How should fosamprenavir be stored?How should fosamprenavir be stored?

How should fosamprenavir be stored?

  • Store fosamprenavir tablets at room temperature, 68°F to 77°F (20°C to 25°C).
  • Store fosamprenavir oral suspension at room temperature or in the refrigerator between 41°F and 86°F (5°C to 30°C). Refrigerating fosamprenavir oral suspension may improve its taste for some people. Do not freeze the oral suspension.
  • Keep fosamprenavir in the container that it came in and keep the container tightly closed.
  • Do not use fosamprenavir if the original seal over the container opening is broken or missing.
  • Throw away fosamprenavir that is no longer needed or expired (out of date). Follow FDA guidelines on how to safely dispose of unused medicine.
  • Keep fosamprenavir and all medicines out of reach of children.
Where can I find more information about fosamprenavir?Where can I find more information about fosamprenavir?

Where can I find more information about fosamprenavir?

Manufacturer Information

ViiV Healthcare

Main number: 877-844-8872
Patient assistance (ViiV Connect): 844-588-3288

Last Reviewed: December 17, 2021