What the label lists and what reports show
Abacavir side effects
Abacavir's FDA label: “The most commonly reported adverse reactions of at least moderate intensity (incidence greater than or equal to 10%) in adult HIV-1 clinical trials were nausea, headache, malaise and fatigue, nausea and vomiting, and dreams/sleep disorders.” FAERS holds 9,685 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 (880 reports).
- Generic listed
- Boxed warning
Check it at the source: the abacavir FDA label on DailyMed (effective July 17, 2025, Mylan Institutional 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 abacavir tablets?Abacavir tablets can cause serious side effects including: See “What is the most important information I should know about abacavir tablets?” Build-up of acid in your blood (lactic acidosis). Lactic acidosis can happen in some people who take abacavir tablets. Lactic acidosis is a serious medical emergency that can cause death. Call your healthcare provider right away if you get any of the following symptoms that could be signs of lactic acidosis: feel very weak or tired unusual (not normal) muscle pain trouble breathing stomach pain with nausea and vomiting feel cold, especially in your arms and legs feel dizzy or light-headed have a fast or irregular heartbeat Serious liver problems can happen in people who take abacavir tablets. In some cases, these serious liver problems can lead to death. […]
Source: FDA drug label, Mylan Institutional Inc., effective July 17, 2025 (SPL set 80c1702a-973c-436a-90f8-69b29674dca0), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most commonly reported adverse reactions of at least moderate intensity (incidence greater than or equal to 10%) in adult HIV-1 clinical trials were nausea, headache, malaise and fatigue, nausea and vomiting, and dreams/sleep disorders.
Table 3. Treatment-Emergent (All Causality) Adverse Reactions of at Least Moderate Intensity (Grades 2-4, Greater than or Equal to 5% Frequency) in Therapy-Naive Adults (CNA3005) through 48 Weeks of Treatment
| Adverse Reaction | Abacavir plus Lamivudine/Zidovudine (n = 262) | Indinavir plus Lamivudine/Zidovudine (n = 264) |
|---|---|---|
| Nausea | 19% | 17% |
| Headache | 13% | 9% |
| Malaise and fatigue | 12% | 12% |
| Nausea and vomiting | 10% | 10% |
| Hypersensitivity reaction | 8% | 2% |
| Diarrhea | 7% | 5% |
| Fever and/or chills | 6% | 3% |
| Depressive disorders | 6% | 4% |
| Musculoskeletal pain | 5% | 7% |
| Skin rashes | 5% | 4% |
| Ear/nose/throat infections | 5% | 4% |
| Viral respiratory infections | 5% | 5% |
| Anxiety | 5% | 3% |
| Renal signs/symptoms | < 1% | 5% |
| Pain (non-site-specific) | < 1% | 5% |
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 other sections of the labeling: Serious and sometimes fatal hypersensitivity reactions [see Boxed Warning, Warnings and Precautions (5.1) ]. Lactic acidosis and severe hepatomegaly with steatosis [see Warnings and Precautions (5.2) ]. Immune reconstitution syndrome [see Warnings and Precautions (5.3) ]. Myocardial infarction [see Warnings and Precautions (5.4) ]. The most commonly reported adverse reactions of at least moderate intensity (incidence greater than or equal to 10%) in adult HIV-1 clinical trials were nausea, headache, malaise and fatigue, nausea and vomiting, and dreams/sleep disorders. ( 6.1 ) The most commonly reported adverse reactions of at least moderate intensity (incidence greater than or equal to 5%) in pediatric HIV-1 clinical trials were fever and/or chills, nausea and vomiting, skin rashes, and ear/nose/throat infections. ( 6.2 ) 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 in Adult Subjects 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 Institutional Inc., effective July 17, 2025 (SPL set 80c1702a-973c-436a-90f8-69b29674dca0), via openFDA; the full label on DailyMed
What do FAERS reports show?
9,685 reports list abacavir among the medicines taken, each a report of something that happened, not proof the medicine caused it; 1,180 are coded as a death and 3,297 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, 10 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?
- Abacavir: 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