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Fosamprenavir Side Effects

Medically reviewed by Last updated on Mar 16, 2023.

Applies to fosamprenavir: oral suspension, oral tablet.

Serious side effects of Fosamprenavir

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

  • Black, tarry stools
  • chills
  • cough
  • fever
  • lower back or side pain
  • painful or difficult urination
  • pale skin
  • skin rash
  • sore throat
  • ulcers, sores, or white spots in the mouth
  • unusual bleeding or bruising
  • unusual tiredness or weakness

Incidence not known

  • Blistering, peeling, loosening of the skin
  • blood in the urine
  • chest pain or discomfort
  • diarrhea
  • itching
  • joint or muscle pain
  • large amount of cholesterol in the blood
  • large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or genitals
  • nausea
  • pain in the groin or genitals
  • pain or discomfort in the arms, jaw, back, or neck
  • red skin lesions, often with a purple center
  • red, irritated eyes
  • sharp back pain just below the ribs
  • sweating
  • vomiting

Other side effects of Fosamprenavir

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:

Less common

  • Headache
  • stomach pain

Incidence not known

  • Burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings in the mouth

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. Discontinuations due to side effects were 6.4% in patients using this drug compared to 5.9% in those using comparator therapies; the most common side effects leading to discontinuation of this drug (incidence up to 1%) included diarrhea, nausea, vomiting, increased AST, increased ALT, and rash.[Ref]


Skin rash (regardless of causality) was reported in about 19% of patients. Rashes were generally maculopapular and of mild or moderate intensity, some with pruritus. Rash had a median onset and duration of 11 and 13 days, respectively, and led to discontinuation of this drug in less than 1% of patients.[Ref]

Very common (10% or more): Skin rash (up to 19%)

Common (1% to 10%): Rash/cutaneous reactions (including erythematous or maculopapular cutaneous eruptions [with or without pruritus])

Rare (0.01% to 0.1%): Severe and/or life-threatening skin reactions (including Stevens-Johnson syndrome)

Frequency not reported: Erythema multiforme, pruritus

Postmarketing reports: Angioedema

Protease inhibitors:

-Frequency not reported: Lipohypertrophy[Ref]


Very common (10% or more): Diarrhea (up to 13%)

Common (1% to 10%): Nausea, vomiting, abdominal pain, increased serum lipase, loose stools, gastritis, abdominal distension, upper abdominal pain, flatulence

Uncommon (0.1% to 1%): Gastroesophageal reflux disease

Frequency not reported: Increased amylase

Postmarketing reports: Oral paresthesia[Ref]

Increased serum lipase (greater than 2 times the upper limit of normal [2 x ULN]) has been reported in up to 8% of patients.

Vomiting was reported more often in pediatric patients than adult patients.[Ref]


Increased fasting triglycerides (greater than 750 mg/dL) have been reported in up to 11% of patients.[Ref]

Very common (10% or more): Increased fasting triglycerides (up to 11%)

Common (1% to 10%): Fatigue

Uncommon (0.1% to 1%): Pyrexia, increased cholesterol

Antiretroviral therapy:

-Frequency not reported: Increased weight, increased blood lipids[Ref]


Common (1% to 10%): Elevated ALT, elevated AST

Frequency not reported: Liver toxicity[Ref]

Elevated ALT (greater than 5 x ULN) and AST (greater than 5 x ULN) have been reported in up to 8% and up to 6% of patients, respectively.[Ref]


Decreased absolute neutrophil count (less than 750 cells/mm3) has been reported in 3% of patients.

Neutropenia was reported more often in pediatric patients than adult patients.[Ref]

Common (1% to 10%): Decreased absolute neutrophil count, neutropenia


-Frequency not reported: Acute hemolytic anemia

Protease inhibitors:

-Frequency not reported: Spontaneous bleeding in patients with hemophilia A and B[Ref]


Increased glucose (greater than 251 mg/dL) has been reported in 2% of patients.[Ref]

Common (1% to 10%): Increased glucose, hyperlipidemia, hypertriglyceridemia

Uncommon (0.1% to 1%): Anorexia

Frequency not reported: Hyperglycemia, increased body fat

Postmarketing reports: Hypercholesterolemia

Protease inhibitors:

-Frequency not reported: Hypertriglyceridemia, hypercholesterolemia, resistance to insulin

-Postmarketing reports: New onset diabetes mellitus, exacerbation of preexisting diabetes mellitus, hyperglycemia, diabetic ketoacidosis

Antiretroviral therapy:

-Frequency not reported: Increased glucose[Ref]

Nervous system

Common (1% to 10%): Headache, dizziness[Ref]


Common (1% to 10%): Drug hypersensitivity[Ref]


Postmarketing reports: Myocardial infarction[Ref]


Postmarketing reports: Nephrolithiasis[Ref]


Frequency not reported: Elevated creatine kinase, osteonecrosis

Protease inhibitors:

-Rare (0.01% to 0.1%): Rhabdomyolysis

-Frequency not reported: Increased creatine phosphokinase, myalgia, myositis[Ref]


Frequency not reported: Depressive/mood disorders[Ref]


Frequency not reported: Immune reconstitution/reactivation syndrome, autoimmune disorders in the setting of immune reconstitution (e.g., Graves' disease, polymyositis, Guillain-Barre syndrome)[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.