Acyclovir is an antiviral medication used to treat infections caused by herpes viruses, including genital herpes, cold sores, shingles, and chickenpox [2]. The drug works by preventing the virus from multiplying and spreading to healthy cells. Acyclovir is generally considered safe and effective when used as prescribed, but like all medications, it can cause side effects and may not be suitable for everyone [2].

One of the main concerns with long-term acyclovir use is the potential for kidney damage [2]. In rare cases, acyclovir can cause acute kidney injury, which can lead to kidney failure if left untreated [2]. Patients with pre-existing kidney disease or those taking other medications that affect kidney function may be at higher risk for this complication [2].

Other potential side effects of acyclovir include nausea, vomiting, diarrhea, headache, dizziness, and fatigue [2,3]. These side effects are usually mild and go away on their own within a few days. More serious side effects, such as allergic reactions, seizures, and confusion, are rare but can occur [3].

In some cases, long-term use of acyclovir can lead to drug-resistant strains of herpes viruses [2]. This can make it more difficult to treat infections in the future and may require the use of stronger medications or combination therapies [2].

Overall, acyclovir is a safe and effective medication when used as prescribed. However, patients should be aware of the potential risks and side effects associated with long-term use and should talk to their healthcare provider if they have any concerns or questions about their treatment [2,3].

Sources:
[1] Drug Patent Watch. Acyclovir. https://www.drugpatentwatch.com/p/tradename/ACYCLOVIR
[2] Healthline. Acyclovir, Oral Tablet. https://www.healthline.com/health/drugs/acyclovir-oral-tablet
[3] Drugs.com. Acyclovir Side Effects. https://www.drugs.com/sfx/acyclovir-side-effects.html