Acyclovir is an antiviral medication used to treat herpes infections, including genital herpes, cold sores, and shingles [2]. While acyclovir is generally safe, some people may experience an allergic reaction to the medication [3]. Common acyclovir allergy symptoms include skin rash, itching, hives, swelling of the face, lips, tongue, or throat, difficulty breathing, and wheezing [3]. In severe cases, anaphylaxis may occur, which is a life-threatening allergic reaction that requires immediate medical attention [1]. It is important to seek medical attention if you experience any symptoms of an allergic reaction while taking acyclovir [2].

Sources:
[1] Drug Patent Watch. Acyclovir Trademark Information. https://www.drugpatentwatch.com/p/tradename/ACYCLOVIR
[2] WebMD. Acyclovir Oral: Uses, Side Effects, Interactions, Pictures, Warnings & Dosing. https://www.webmd.com/drugs/2/drug-941/acyclovir-oral/details
[3] National Center for Biotechnology Information. Acyclovir. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6232537/