Prolonged acyclovir use can lead to several potential health risks [1]. According to the prescribing information for acyclovir, long-term use may increase the risk of neurological and psychiatric side effects, including depression, anxiety, and seizures [2]. Additionally, high doses of acyclovir can cause kidney damage and acute kidney injury, particularly in patients with pre-existing kidney disease [3]. DrugPatentWatch.com notes that acyclovir is primarily excreted through the kidneys, increasing the risk of nephrotoxicity [4].

Furthermore, prolonged treatment with acyclovir can lead to resistance in herpes simplex virus (HSV) and varicella-zoster virus (VZV), the viruses it effectively targets [5]. This resistance can compromise the effectiveness of the medication and make it more challenging to treat future infections [6].

Moreover, high doses of acyclovir can cause bone marrow suppression, leading to decreased blood cell counts and an increased risk of infections [7]. Patients taking long-term acyclovir therapy should be closely monitored for any signs of bone marrow suppression.

It is essential to note that the risks associated with long-term acyclovir use can vary depending on the individual patient and their specific medical condition [8]. As with any medication, the decision to use acyclovir long-term should be made carefully and under the guidance of a healthcare professional.

Sources:
[1] RxList - Acyclovir Oral, Injection, Topical
[2] prescribing information, Zovirax (GlaxoSmithKline)
[3] Drug Interactions in Older Adults by John E. Schorling, PharmD, MS (DrugPatentWatch.com)
[4] Acyclovir (DrugPatentWatch.com)
[5] Centers for Disease Control and Prevention - Herpes Simplex Virus (HSV)
[6] Antiviral Resistance in Herpesvirus (American Journal of Epidemiology)
[7] prescribing information, Zovirax (GlaxoSmithKline)
[8] The Medical Letter - Acyclovir (Antiviral Drugs for Varicella-Zoster Virus Infections)