What the label lists and what reports show
Fostemsavir side effects
Fostemsavir's FDA label: “The most common adverse reaction (all grades) observed in ≥5% of subjects was nausea.” FAERS holds 238 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 nausea (17 reports).
- No generic listed
Check it at the source: the fostemsavir FDA label on DailyMed (effective February 13, 2024, ViiV Healthcare Company); 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 RUKOBIA?RUKOBIA can cause serious side effects including: • Changes in your immune system (Immune Reconstitution Syndrome) can happen when you start taking HIV-1 medicine. Your immune system may get stronger and begin to fight infections that have been hidden in your body for a long time. Tell your healthcare provider right away if you start having new symptoms after you start taking RUKOBIA. • Heart rhythm problems (QTc prolongation). RUKOBIA may cause a heart rhythm problem called QTc prolongation. QTc prolongation causes an irregular heartbeat. If you are elderly, or if you take certain other medicines, you may be at a greater risk for developing this heart problem with RUKOBIA. Tell your healthcare provider right away if you feel dizzy, lightheaded, feel changes in your heartbeat, or you faint (lose consciousness). • Changes in liver function blood tests results. […]
Source: FDA drug label, ViiV Healthcare Company, effective February 13, 2024 (SPL set a21006b7-6d6f-4f06-81b4-17978756452b), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most common adverse reaction (all grades) observed in ≥5% of subjects was nausea.
Table 1. Adverse Reactions a (Grades 1 to 4) Reported in ≥2% of Subjects Receiving RUKOBIA plus OBT in the BRIGHTE Trial, Randomized Cohort (Week 96 Analysis)
| Adverse Reaction | OBT = Optimized background therapy. a Frequencies of adverse reactions are based on all treatment-emergent adverse events… RUKOBIA plus OBT (n = 271) b |
|---|---|
| Nausea | 10% |
| Diarrhea | 4% |
| Headache | 4% |
| Abdominal pain c | 3% |
| Dyspepsia | 3% |
| Fatigue d | 3% |
| Rash e | 3% |
| Sleep disturbance f | 3% |
| Immune Reconstitution Inflammatory Syndrome | 2% |
| Somnolence | 2% |
| Vomiting | 2% |
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, continuedThe following adverse reactions are discussed in greater detail in other sections of the labeling: • Immune reconstitution syndrome [see Warnings and Precautions ( 5.1 )]. • QTc prolongation [see Warnings and Precautions ( 5.2 )]. • Elevations in hepatic transaminases in patients with hepatitis B or C virus co-infection [see Warnings and Precautions ( 5.3 )]. The most common adverse reaction (all grades) observed in ≥5% of subjects was nausea. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact ViiV Healthcare at 1-877-844-8872 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 practice. A total of 620 subjects with HIV-1 infection received at least one dose of RUKOBIA as part of a controlled clinical trial. The primary safety assessment of RUKOBIA is based on 96 weeks of data from a Phase 3 partially randomized, international, multicenter, double-blind, placebo-controlled trial (BRIGHTE) conducted in 371 heavily treatment-experienced adult subjects [see Clinical Studies ( 14 )]. …
Source: FDA drug label, ViiV Healthcare Company, effective February 13, 2024 (SPL set a21006b7-6d6f-4f06-81b4-17978756452b), via openFDA; the full label on DailyMed
What do FAERS reports show?
238 reports list fostemsavir among the medicines taken, each a report of something that happened, not proof the medicine caused it; 19 are coded as a death and 23 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 19 reactions below, 7 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?
- Fostemsavir: 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