What the label lists and what reports show
Fosamprenavir side effects
Fosamprenavir's FDA label: “The most common moderate to severe adverse reactions in clinical trials of fosamprenavir were diarrhea, rash, nausea, vomiting, and headache.” FAERS holds 130 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is anaemia (27 reports).
- Generic listed
Check it at the source: the fosamprenavir FDA label on DailyMed (effective September 15, 2023, Mylan Pharmaceuticals Inc.); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of fosamprenavir calcium tablets?Fosamprenavir calcium tablets may cause serious side effects including: • See “What is the most important information I should know about fosamprenavir calcium tablets?” • Liver problems. Your healthcare provider should do blood tests before and during your treatment with fosamprenavir calcium tablets to check your liver function. Some people with liver problems, including hepatitis B or C, may have an increased risk of developing worsening liver problems during treatment with fosamprenavir calcium tablets. • Diabetes and high blood sugar (hyperglycemia). Some people who take protease inhibitors, including fosamprenavir calcium tablets, can get high blood sugar, develop diabetes, or your diabetes can get worse. Tell your healthcare provider if you notice an increase in thirst or urinate often during treatment with fosamprenavir calcium tablets. […]
Source: FDA drug label, Mylan Pharmaceuticals Inc., effective September 15, 2023 (SPL set 3a1424d8-844c-4e24-9ebd-b2c2b61b61a3), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most common moderate to severe adverse reactions in clinical trials of fosamprenavir were diarrhea, rash, nausea, vomiting, and headache.
Table 2. Selected Moderate/Severe Clinical Adverse Reactions Reported in Greater than or Equal to 2% of Antiretroviral-Naive Adult Subjects
| Reaction | Fosamprenavir 1,400 mg Twice Daily (n = 166) | Nelfinavir 1,250 mg Twice Daily (n = 83) | Fosamprenavir 1,400 mg and Ritonavir 200 mg Once Daily (n = 322) | Nelfinavir 1,250 mg Twice Daily (n = 327) |
|---|---|---|---|---|
| Diarrhea | 5% | 18% | 10% | 18% |
| Nausea | 7% | 4% | 7% | 5% |
| Vomiting | 2% | 4% | 6% | 4% |
| Abdominal pain | 1% | 0% | 2% | 2% |
| Rash | 8% | 2% | 3% | 2% |
| Fatigue | 2% | 1% | 4% | 2% |
| Headache | 2% | 4% | 3% | 3% |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedSevere or life-threatening skin reactions have been reported with the use of fosamprenavir [see Warnings and Precautions (5.2) ]. • The most common moderate to severe adverse reactions in clinical trials of fosamprenavir were diarrhea, rash, nausea, vomiting, and headache. • Treatment discontinuation due to adverse events occurred in 6.4% of subjects receiving fosamprenavir and in 5.9% of subjects receiving comparator treatments. The most common adverse reactions leading to discontinuation of fosamprenavir (incidence less than or equal to 1% of subjects) included diarrhea, nausea, vomiting, AST increased, ALT increased, and rash. • In adults the most common adverse reactions (incidence greater than or equal to 4%) are diarrhea, rash, nausea, vomiting, and headache. ( 6.1 ) • Vomiting and neutropenia were more frequent in pediatrics than in adults. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Mylan at 1-877-446-3679 (1-877-4-INFO-RX) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.
Source: FDA drug label, Mylan Pharmaceuticals Inc., effective September 15, 2023 (SPL set 3a1424d8-844c-4e24-9ebd-b2c2b61b61a3), via openFDA; the full label on DailyMed
What do FAERS reports show?
130 reports list fosamprenavir among the medicines taken, each a report of something that happened, not proof the medicine caused it; 10 are coded as a death and 21 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 21 reactions below, 3 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Fosamprenavir: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions