What the label lists and what reports show
Nelfinavir side effects
Nelfinavir's FDA label: “Most common adverse reactions (≥2%) of moderate or severe intensity in adults and adolescents (13 years and older) are diarrhea, nausea, rash, and flatulence ( 6.1 ) • Most common adverse reactions in pediatric patients (2 to less than 13 years) are diarrhea …” FAERS holds 2,090 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 pain (244 reports).
- No generic listed
Check it at the source: the nelfinavir FDA label on DailyMed (effective December 11, 2025, AGOURON); 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 VIRACEPT?VIRACEPT can cause serious side effects, including: • Diabetes and high blood sugar (hyperglycemia). Some people who take protease inhibitors including VIRACEPT can get high blood sugar, develop diabetes, or your diabetes can get worse. Some people have had to start taking medicine to treat diabetes or have had to change their diabetes medicine. Tell your healthcare provider if you notice an increase in thirst or urinate often while taking VIRACEPT. • Increased bleeding in people with hemophilia. Some people with hemophilia have increased bleeding with protease inhibitors including VIRACEPT. • Changes in body fat. These changes can happen in people taking HIV-1 medicine. The changes may include an increased amount of fat in the upper back and neck ("buffalo hump"), breast, and around the middle of your body (trunk). Loss of fat from the legs, arms, and face may also happen. […]
Source: FDA drug label, AGOURON, effective December 11, 2025 (SPL set e72c2bc6-9462-4a2e-8e1d-b97592376cbd), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsMost common adverse reactions (≥2%) of moderate or severe intensity in adults and adolescents (13 years and older) are diarrhea, nausea, rash, and flatulence ( 6.1 ) • Most common adverse reactions in pediatric patients (2 to less than 13 years) are diarrhea, leukopenia/neutropenia, rash, anorexia, and abdominal pain.
Table 4: Percentage of Patients with Treatment-Emergent Includes those adverse events at least possibly, probably or definitely related to study drug or of unknown relationship and excludes concurrent HIV conditions…
| Adverse Events | Placebo + ZDV/3TC (n=101) | 500 mg TID VIRACEPT + ZDV/3TC (n=97) | 750 mg TID VIRACEPT + ZDV/3TC (n=100) | 1250 mg BID VIRACEPT + d4T/3TC (n=344) | 750 mg TID VIRACEPT + d4T/3TC (n=210) |
|---|---|---|---|---|---|
| Diarrhea | 3% | 14% | 20% | 20% | 15% |
| Nausea | 4% | 3% | 7% | 3% | 3% |
| Flatulence | 0 | 5% | 2% | 1% | 1% |
| Rash | 1% | 1% | 3% | 2% | 1% |
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, continuedBecause clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. • Most common adverse reactions (≥2%) of moderate or severe intensity in adults and adolescents (13 years and older) are diarrhea, nausea, rash, and flatulence ( 6.1 ) • Most common adverse reactions in pediatric patients (2 to less than 13 years) are diarrhea, leukopenia/neutropenia, rash, anorexia, and abdominal pain. ( 6.2 ) To report SUSPECTED ADVERSE REACTIONS, contact Pfizer Inc at 1-800-438-1985 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience: Adults and Adolescents (13 years and older) The safety of VIRACEPT was studied in over 5000 patients who received drug either alone or in combination with nucleoside analogues. The majority of adverse events were of mild intensity. The most frequently reported adverse event among patients receiving VIRACEPT was diarrhea, which was generally of mild to moderate intensity. Drug-related clinical adverse experiences of moderate or severe intensity in ≥2% of patients treated with VIRACEPT coadministered with d4T and 3TC (Study 542) for up to 48 weeks, or with ZDV plus 3TC (Study 511) for up to 24 weeks are presented in Table 4.
Source: FDA drug label, AGOURON, effective December 11, 2025 (SPL set e72c2bc6-9462-4a2e-8e1d-b97592376cbd), via openFDA; the full label on DailyMed
What do FAERS reports show?
2,090 reports list nelfinavir among the medicines taken, each a report of something that happened, not proof the medicine caused it; 110 are coded as a death and 674 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 23 reactions below, 5 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.
Reports received each year
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?
- Nelfinavir: 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