What are the next steps after prescribing acyclovir (antiviral medication) 400 mg three times a day (TDS) for 5 days for shingles and ordering an HIV test?

Next Steps After Prescribing Acyclovir 400mg TDS for Shingles

Critical Issue: Your Dosing is Incorrect and Inadequate

You need to immediately correct the acyclovir dose to 800mg five times daily (every 4 hours while awake) and extend the duration to 7-10 days, continuing until all lesions have completely scabbed. 1, 2

Why Your Current Prescription is Wrong:

• The FDA-approved dose for herpes zoster is 800mg orally every 4 hours, 5 times daily for 7-10 days 2
• Your prescribed dose of 400mg TDS (three times daily) is only appropriate for genital herpes or HSV suppression in HIV patients, not for shingles 3, 2
• Research demonstrates that 800mg five times daily is superior to 400mg five times daily for herpes zoster, with the lower dose showing no significant benefit over placebo 4

Immediate Action Required

Contact the patient immediately to correct the prescription:

• Change to: Acyclovir 800mg orally 5 times daily (every 4 hours while awake) for 7-10 days 1, 2
• Continue treatment until ALL lesions have completely scabbed, not just for an arbitrary 5-7 days 1
• Treatment is most effective when started within 72 hours of rash onset, ideally within 48 hours 1

Monitoring and Follow-Up

Clinical monitoring endpoints:

• Assess for complete scabbing of all lesions - this is your treatment endpoint, not calendar days 1
• Monitor for signs of dissemination (multi-dermatomal involvement, visceral symptoms) which would require IV acyclovir 1
• Watch for complications including postherpetic neuralgia, ophthalmic involvement, or CNS symptoms 1

If the patient is immunocompromised or HIV-positive:

• Consider IV acyclovir 10mg/kg every 8 hours instead of oral therapy 1
• Higher oral doses (up to 800mg 5-6 times daily) may be needed 3, 5
• Temporarily reduce immunosuppressive medications if applicable 1

Regarding the HIV Test

The HIV test you ordered is appropriate because:

• Herpes zoster in younger patients or with severe/atypical presentation may indicate underlying immunosuppression 3, 1
• HIV-infected patients with herpes zoster may require higher doses or IV therapy 3, 5
• If HIV-positive, the patient may benefit from long-term acyclovir prophylaxis (400mg 2-3 times daily) 3, 5

Follow-up on HIV results:

• If positive: Consider increasing acyclovir dose to 400mg 3-5 times daily until clinical resolution 3
• If positive with severe disease: Switch to IV acyclovir 3
• Monitor for acyclovir resistance if lesions persist despite treatment 3

Infection Control Counseling

Advise the patient:

• Avoid contact with pregnant women, immunocompromised individuals, and those who haven't had chickenpox until all lesions are crusted 1
• Lesions are contagious and can transmit varicella to susceptible individuals 1

Prevention for Future

After recovery, recommend:

• Recombinant zoster vaccine (Shingrix) for adults ≥50 years, regardless of this episode 1
• Vaccination should occur after complete healing 1

Common Pitfall You Made

The most critical error here is underdosing - 400mg TDS is approximately half the required dose for shingles and will likely result in treatment failure, prolonged symptoms, and increased risk of postherpetic neuralgia 2, 4. This is a common mistake when providers confuse HSV dosing with VZV dosing.