Acyclovir is an antiviral medication used to treat infections caused by the herpes virus, including genital herpes, cold sores, shingles, and chickenpox. According to Drug Patent Watch [1], the FDA has approved acyclovir for long-term use in the suppression of recurrent genital herpes infections. However, the use of acyclovir for extended periods may have some side effects.

A study published in the Journal of Infectious Diseases [3] suggests that long-term use of acyclovir can lead to the development of drug-resistant strains of the herpes virus. The study also notes that the use of acyclovir for extended periods can cause a decrease in the effectiveness of the drug over time.

Another study published in PubMed [2] indicates that acyclovir is generally well-tolerated and safe for long-term use in the suppression of recurrent genital herpes infections. However, the study notes that patients with renal impairment may experience adverse effects when taking acyclovir for extended periods.

In conclusion, acyclovir can be taken for extended periods for the suppression of recurrent genital herpes infections, but it may lead to the development of drug-resistant strains of the herpes virus and a decrease in the effectiveness of the drug over time. Patients with renal impairment should be cautious when taking acyclovir for extended periods. It is important to consult a healthcare professional before taking any medication for an extended period.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/ACYCLOVIR
[2] https://pubmed.ncbi.nlm.nih.gov/2895840/
[3] https://academic.oup.com/jid/article/186/Supplement_1/S40/837474