First-Line Medication for Herpes Simplex
Acyclovir is the first-line medication for herpes simplex virus infections, with specific dosing regimens depending on whether it is a first clinical episode or recurrent infection. 1
Treatment Regimens
First Clinical Episode
- Recommended regimens 2, 1:
- Acyclovir 400 mg orally three times a day for 7-10 days, OR
- Acyclovir 200 mg orally five times a day for 7-10 days, OR
- Famciclovir 250 mg orally three times a day for 7-10 days, OR
- Valacyclovir 1 g orally twice a day for 7-10 days
Recurrent Episodes
- Recommended regimens 2, 1:
- Acyclovir 200 mg orally 5 times a day for 5 days, OR
- Acyclovir 400 mg orally 3 times a day for 5 days, OR
- Acyclovir 800 mg orally 2 times a day for 5 days
Treatment Approach Based on Frequency of Recurrence
Episodic Therapy
- For patients with fewer than 6 outbreaks per year 1
- Start treatment at first sign of prodrome or within 1 day of lesion onset
- Use standard dosing regimens for recurrent episodes
Suppressive Therapy
- For patients with 6 or more recurrences per year 2, 1
- Reduces recurrence frequency by ≥75%
- After 1 year of continuous suppressive therapy, consider discontinuing to reassess recurrence frequency
Special Considerations
Immunocompromised Patients
- May require more aggressive therapy and longer treatment courses 1
- Higher risk of treatment failure and development of acyclovir-resistant strains 3
- For acyclovir-resistant HSV, foscarnet 40 mg/kg IV three times daily or 60 mg/kg IV twice daily is recommended 3
Renal Impairment
Dosage adjustment is necessary based on creatinine clearance 1, 4:
- Creatinine clearance >10 mL/min/1.73m²:
- 200 mg regimen: 200 mg every 4 hours
- 400 mg regimen: 400 mg every 12 hours
- 800 mg regimen: 800 mg every 4 hours
- Creatinine clearance 0-10 mL/min/1.73m²:
- 200 mg regimen: 200 mg every 12 hours
- 400 mg regimen: 200 mg every 12 hours
- 800 mg regimen: 800 mg every 12 hours
Severe Cases
- Hospitalization and IV acyclovir (5-10 mg/kg every 8 hours) may be necessary for severe cases 1
- Treatment may be extended if healing is incomplete after 10 days of therapy 2
Important Clinical Pearls
Early treatment initiation: Maximum therapeutic benefit is achieved when treatment is started within the first 3 days of symptom onset 5, 6
Topical therapy limitations: Topical acyclovir is substantially less effective than oral therapy and is not recommended 2, 1
Persistence of latent virus: Acyclovir neither eradicates latent virus nor affects subsequent risk, frequency, or severity of recurrences after the drug is discontinued 2
Patient counseling: Advise patients to abstain from sexual activity while lesions are present to prevent transmission 1
Monitoring: For patients on high doses or with renal impairment, monitor for neurological symptoms (confusion, agitation, hallucinations) which may indicate acyclovir neurotoxicity 1
Hydration: Adequate fluid intake during treatment is essential to minimize the risk of nephrotoxicity 1