Who should not take acyclovir for herpes?
Acyclovir (including formulations used to treat herpes infections such as genital herpes, herpes labialis/cold sores, and herpes zoster) is contraindicated in people who have had a hypersensitivity (allergic) reaction to acyclovir or to valacyclovir (the related antiviral prodrug).
What specific allergy reactions count as contraindications?
The key contraindication is a known allergy to acyclovir or valacyclovir. If a person previously developed an allergic reaction to either drug, they should not take acyclovir again.
Are there situations where acyclovir is still used but with extra caution?
The question of “contraindications” is separate from “warnings/precautions.” Even when a patient is not allergic, clinicians may still monitor carefully for issues such as kidney function (acyclovir is cleared by the kidneys) and adjust dosing in renal impairment. These are precautions, not absolute contraindications, when there is no prior drug allergy.
Does the contraindication change by herpes type or by formulation?
No. The core contraindication remains hypersensitivity to acyclovir (or valacyclovir). The herpes indication (cold sores vs genital herpes vs shingles) may change the dose, duration, and route, but it does not change the allergy-based contraindication.
Are there patent or product-specific label differences?
Contraindications are generally consistent across acyclovir products because they come from the drug’s prescribing information. If you tell me the exact product name and dose form (tablet, capsule, suspension, or IV) and your country, I can align the contraindication wording to that specific label.
Sources: none provided.