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Fosamprenavir Side Effects

In Summary

Commonly reported side effects of fosamprenavir include: skin rash. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to fosamprenavir: oral suspension, oral tablet

Along with its needed effects, fosamprenavir may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking fosamprenavir:

More common

Less common

  • Abdominal or stomach pain
  • blurred vision
  • depression
  • dry mouth
  • flushed, dry skin
  • fruit-like breath odor
  • increased hunger
  • increased thirst
  • increased urination
  • mood or mental changes
  • nausea
  • sweating
  • troubled breathing
  • unexplained weight loss
  • unusual tiredness or weakness
  • vomiting


  • Back, leg, or stomach pains
  • bleeding gums
  • blistering, peeling, or loosening of the skin
  • chills
  • cough
  • dark urine
  • diarrhea
  • difficulty with breathing
  • fever
  • general body swelling
  • itching
  • joint or muscle pain
  • loss of appetite
  • nosebleeds
  • pale skin
  • red skin lesions often with a purple center
  • red, irritated eyes
  • sore throat
  • sores, ulcers, or white spots in the mouth or on the lips
  • yellowing of the eyes or skin

Incidence not known

  • Large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs

Some side effects of fosamprenavir may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  • Mild or moderate rash

Less common

  • Burning or prickling sensation around the mouth
  • headache

Incidence not known

  • Breast enlargement
  • buffalo hump
  • increased fat deposits on the face, neck, and trunk
  • obesity

For Healthcare Professionals

Applies to fosamprenavir: oral suspension, oral tablet


Diarrhea, rash, nausea, vomiting, and headache were the most frequent moderate to severe side effects in clinical trials of fosamprenavir. Discontinuations due to side effects were 6.4% in patients receiving fosamprenavir compared to 5.9% in those receiving comparator therapies. The most common side effects leading to fosamprenavir discontinuation (incidence of 1% or less) included diarrhea, nausea, vomiting, increased AST, increased ALT, and rash.[Ref]


Dermatologic side effects of moderate to severe intensity have included rash (up to 8%) in patients treated with combination therapy. Skin rash, regardless of causality, occurred in approximately 19% of patients treated with fosamprenavir in studies. Rashes were generally maculopapular and of mild or moderate intensity, some with pruritus. Severe or life-threatening skin reactions, including at least 1 case of Stevens-Johnson syndrome, have been reported during clinical trials. Erythema multiforme has been reported in at least 1 patient receiving fosamprenavir with ritonavir, zidovudine, and lamivudine. Angioedema has been reported during postmarketing experience.[Ref]

Skin rash, regardless of causality, had a median onset and duration of 11 and 13 days, respectively, and led to discontinuation of fosamprenavir in less than 1% of patients.[Ref]


Gastrointestinal side effects of moderate to severe intensity have included diarrhea (up to 13%), nausea (up to 7%), vomiting (up to 6%), and abdominal pain (up to 2%) in patients treated with combination therapy.[Ref]


The mechanism and long-term consequences of body fat redistribution/accumulation are currently unknown and a causal relationship has not been established.[Ref]

Metabolic side effects have included increased serum lipase (greater than 2 times ULN; up to 8%), triglycerides (greater than 750 mg/dL; up to 11%), glucose (greater than 251 mg/dL; 2%), and amylase. Redistribution/accumulation of body fat, including central obesity, dorsocervical fat enlargement, peripheral wasting, facial wasting, breast enlargement, and "cushingoid appearance," have been observed in patients receiving antiretroviral therapy, including fosamprenavir. Hypercholesterolemia has been reported during postmarketing experience. New onset diabetes mellitus, exacerbation of preexisting diabetes mellitus, and hyperglycemia have been reported during postmarketing experience in HIV-infected patients receiving protease inhibitor therapy; however, causality has not been established.[Ref]


Hepatic side effects have included elevated ALT (greater than 5 times ULN; up to 8%) and AST (greater than 5 times ULN; up to 6%). Liver toxicity has been reported in patients receiving fosamprenavir with ritonavir, zidovudine, and lamivudine.[Ref]

Nervous system

Nervous system side effects of moderate to severe intensity have included headache (up to 4%) in patients treated with combination therapy. Oral paresthesia has been reported during postmarketing experience.[Ref]


Other side effects of moderate to severe intensity have included fatigue (up to 4%) in patients treated with combination therapy. Elevated creatine kinase has been reported.[Ref]


Hematologic side effects have included neutropenia (less than 750 cells/mm3; 3%). Acute hemolytic anemia has been associated with amprenavir. Hematologic side effects associated with protease inhibitors have included spontaneous bleeding in patients with hemophilia A and B. In many of the reported cases, treatment with protease inhibitors was continued or restarted and some patients required additional factor VIII. A causal relationship between protease inhibitor therapy and these episodes has not been established.[Ref]


Psychiatric side effects have included depressive/mood disorders.[Ref]


Cardiovascular side effects have included myocardial infarction during postmarketing experience.[Ref]


Genitourinary side effects have included nephrolithiasis during postmarketing experience.[Ref]


Immunologic side effects have included immune reconstitution syndrome. Autoimmune disorders (e.g., Graves' disease, polymyositis, and Guillain-Barre syndrome) have been reported in the setting of immune reconstitution.[Ref]


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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.