Yes. 6 FDA-approved labels for Abacavir Sulfate carry a boxed warning, and its subject is hypersensitivity reactions. A boxed warning is the most serious warning the FDA requires on a prescription label. It is applied to the drug and to the situations in which it is used, not to any particular person taking it.
What the warning says
Below is how the Abacavir Sulfate warning opens on one specific label, identified underneath it. Of the 6 Abacavir Sulfate labels sampled, 3 carried materially different wordings, and this was the most common, used by 3 of them.
WARNING: HYPERSENSITIVITY REACTIONS Serious and sometimes fatal hypersensitivity reactions, with multiple organ involvement, have occurred with abacavir. Patients who carry the HLA-B*5701 allele are at a higher risk of a hypersensitivity reaction to abacavir; although, hypersensitivity reactions have occurred in patients who do not carry the HLA-B*5701 allele [see Warnings and Precautions (5.1) ] . Abacavir tablets are contraindicated in patients with a prior hypersensitivity reaction to abacavir and in HLA-B*5701-positive patients [see Contraindications (4) , Warnings and Precautions (5.1) ] .
ABACAVIR SULFATE, Mylan Pharmaceuticals Inc., label version effective 08 January 2021. Opening of the warning; read the full label on DailyMed.Why the wording differs between manufacturers
There is no single official text of a boxed warning. The FDA sets what a warning must cover, and each manufacturer writes its own label within that. Of the 6 Abacavir Sulfate labels sampled for this page, 3 carried materially different wordings of the same warning, and the version quoted above was used by 3 of them.
The hazard does not change between those 3 versions. Only the sentences do, which is why a refill from a different manufacturer can carry warning text that reads differently without anything about Abacavir Sulfate or its risks having changed.
Abacavir Sulfate is dispensed under 6 current FDA labels despite this warning, which is the point worth holding onto: a boxed warning is a disclosure requirement, not a verdict. What a boxed warning does and does not mean sets out the distinction.
Common questions
Does Abacavir Sulfate have a black box warning?
Yes. 6 FDA-approved labels for Abacavir Sulfate carry a boxed warning, and its subject is hypersensitivity reactions. A boxed warning is the strongest warning the FDA requires on a prescription label, and it is applied to the drug, not to any individual taking it.
What does the Abacavir Sulfate boxed warning say?
The wording is set by each manufacturer within FDA requirements, so it varies. In the version quoted on this page, taken from a label effective 08 January 2021, the warning concerns hypersensitivity reactions. The full text is linked so the exact version can be read rather than summarised.
Does the Abacavir Sulfate boxed warning mean the drug is unsafe or being withdrawn?
No. It means the FDA requires the risk of hypersensitivity reactions to be communicated prominently so prescribers weigh it explicitly. Abacavir Sulfate remains FDA-approved and is dispensed under 6 current labels. A boxed warning is a disclosure requirement, not a judgement that a drug should not be used.
Why do different pharmacies show different warning text for the same drug?
Because each manufacturer writes its own label within the FDA's requirements. Of 6 Abacavir Sulfate labels sampled here, 3 carried materially different wordings of the same warning. The hazard described is the same; the sentences are not. This is a common source of confusion when a prescription is refilled with a different manufacturer's product.
Should I stop taking Abacavir Sulfate because of this warning?
This page does not answer that and cannot. The warning about hypersensitivity reactions is written for a prescriber deciding whether Abacavir Sulfate suits a particular patient, and stopping a prescribed medicine carries its own risks that this page knows nothing about. Raise it with the prescriber or a pharmacist, who can see the whole picture.
Where this page's information comes from
The quotation above is from one Abacavir Sulfate label, linked below by its DailyMed set identifier so the exact version can be opened rather than taken on trust. The figure of 6 labels, and the count of 3 distinct wordings among 6 sampled, were computed from the openFDA labelling API on 30 August 2026.
- ABACAVIR SULFATE prescribing information, Mylan Pharmaceuticals Inc., effective 08 January 2021.
- openFDA drug labelling API, the source of the label counts and variant counts on this page.
Labels are revised over time. The version linked above is the one this page was written against, and a newer revision may differ. Counts reflect the labels present in openFDA on the retrieval date.