Abacavir

What abacavir is used for

Abacavir is a nucleoside reverse transcriptase inhibitor used as part of combination treatment for HIV. It is available as an individual medicine and in fixed-dose combinations. This overview uses the ZIAGEN prescribing information for abacavir tablets and oral solution. It is not a guide to replacing one combination product with another, and abacavir alone is not a complete HIV regimen.

The allergy check is essential

A blood test for HLA-B*5701 is required before starting abacavir or restarting it when a result has not already been documented. Abacavir must not be used in people who carry this allele or who have had an abacavir hypersensitivity reaction. A negative test does not eliminate every possibility of a reaction. The medicine is also contraindicated in moderate or severe liver impairment.

A possible hypersensitivity reaction can involve fever, rash, stomach or bowel symptoms, marked tiredness and respiratory symptoms. Contact the treating team urgently if a reaction is suspected. After an abacavir allergy, taking abacavir again can cause a rapid, life-threatening reaction. If treatment has been interrupted for any reason, obtain instructions before restarting rather than assuming that prior tolerance guarantees safety.

Documented interaction questions

Abacavir increased methadone clearance in a small pharmacokinetic study. Most patients did not require a methadone change, but a minority may need clinical reassessment; dose changes belong with the prescribing team. Increased riociguat exposure was reported with the fixed-dose abacavir/dolutegravir/lamivudine combination, so the riociguat prescriber needs to review this combination and monitor tolerability. The exact increase should not be assumed to be identical in every patient.

ZIAGEN oral solution contains sorbitol, which can lower lamivudine exposure. This is a liquid-formulation interaction, not a general prohibition on abacavir plus lamivudine tablets. Alcohol also increased abacavir exposure in a pharmacokinetic study; the label does not establish a universal alcohol-risk category.

Other safety and follow-up points

Nausea, headache, tiredness and sleep-related symptoms have been reported during abacavir-containing treatment. Important warnings include lactic acidosis, serious liver problems and immune-reconstitution inflammation. Evidence linking abacavir to heart attack is inconsistent; cardiovascular risk factors should be reviewed without claiming that causation has been proved. Pregnancy requires review of the complete regimen. Current NIH infant-feeding guidance uses shared decision-making: sustained viral suppression reduces but does not eliminate breastfeeding transmission risk; formula or banked pasteurized donor milk avoids that transmission route. Follow current local specialist advice and maternal and infant monitoring plans.

Sources: DailyMed: ZIAGEN prescribing information; EMA: ZIAGEN medicine overview and ATC; NIH: Preventing HIV transmission during infant feeding. Sources checked 4 November 2026; source verification is separate from independent clinical review.