What is the recommended treatment for an adult over 50 with a history of chickenpox diagnosed with shingles?

Treatment of Shingles in Adults Over 50

For an adult over 50 with shingles, initiate oral antiviral therapy with valacyclovir 1000 mg three times daily, acyclovir 800 mg five times daily, or famciclovir 500 mg three times daily for 7 days, ideally within 72 hours of rash onset, and most effectively within 48 hours. 1, 2

Antiviral Therapy: The Cornerstone of Treatment

Medication Selection and Dosing

• Acyclovir 800 mg orally five times daily for 7-10 days is the FDA-approved regimen that significantly shortens time to lesion scabbing, healing, and complete cessation of pain 1
• Valacyclovir and famciclovir are equally effective alternatives with more convenient dosing schedules (three times daily versus five times daily) 2, 3
• Treatment effectiveness is time-dependent: maximum benefit occurs when started within 48 hours of rash onset, with diminishing returns after 72 hours 1, 2

Evidence for Antiviral Efficacy

• In immunocompetent patients with localized cutaneous zoster, acyclovir shortened times to lesion scabbing, healing, and complete cessation of pain, and reduced duration of viral shedding 1
• Adults greater than 50 years of age showed greater benefit from antiviral treatment compared to younger patients 1
• Antivirals reduce the prevalence of localized zoster-associated neurologic symptoms including paresthesia, dysesthesia, and hyperesthesia 1

Pain Management During Acute Phase

Acute Pain Control

• Administer analgesics appropriate to pain severity, ranging from acetaminophen/NSAIDs for mild pain to opioids for severe acute neuritis 4, 2
• For severe acute neuritis, consider amitriptyline hydrochloride or other tricyclic antidepressants early in the disease course 4
• Gabapentin initiated concomitantly with antivirals as soon as the rash develops may reduce severity of complications, though data on preventing postherpetic neuralgia remain limited 3

Prevention of Postherpetic Neuralgia (PHN)

Understanding the Risk

• Approximately 20% of patients with shingles develop PHN, defined as pain persisting at least 90 days after acute herpes zoster 2
• The risk increases dramatically with age, making prevention critical in patients over 50 5, 2

Preventive Strategies

• Early antiviral therapy (within 72 hours) may help prevent PHN development according to some evidence, though this remains somewhat controversial 6
• Antivirals during the acute phase significantly reduce the intensity of acute pain and accelerate healing, which correlates with lower PHN risk 6
• There is no convincing evidence that antivirals alone definitively reduce the risk of PHN, making early comprehensive pain management essential 6

Dosage Adjustments for Special Populations

Renal Impairment

• Acyclovir half-life and total body clearance depend on renal function, requiring dosage adjustment in patients with reduced renal function 1
• Geriatric patients have higher acyclovir plasma concentrations due to age-related changes in renal function, necessitating dose reduction in those with underlying renal impairment 1

Drug Interactions

• Coadministration of probenecid with acyclovir increases mean acyclovir half-life and area under the concentration-time curve, with correspondingly reduced urinary excretion and renal clearance 1

Monitoring for Complications

Common Complications to Watch For

• Postherpetic neuralgia lasting weeks to years is the most frequent complication 4, 2
• Ocular complications including keratitis, iridocyclitis, secondary glaucoma, and vision loss require immediate ophthalmology referral when trigeminal ganglion is involved 4
• Neurological complications such as motor neuropathies, encephalitis, and Guillain-Barré syndrome occur rarely but require urgent evaluation 4
• Secondary bacterial infection of vesicles should be treated with appropriate antibiotics 4, 2

Critical Pitfalls to Avoid

Timing Errors

• Do not delay antiviral therapy beyond 72 hours of rash onset, as efficacy diminishes significantly 1, 2
• Do not wait for laboratory confirmation to initiate treatment in typical presentations—diagnosis is clinical 4

Inadequate Pain Management

• Do not undertreat acute pain, as inadequate control may increase PHN risk 2, 3
• Do not rely solely on antivirals for pain management—multimodal analgesia is essential 2

Missed Vaccination Opportunity

• After acute symptoms resolve (typically waiting at least 2 months), recommend Shingrix vaccination to prevent future episodes, as having shingles once does not provide reliable protection against recurrence 7
• The 10-year cumulative recurrence risk is 10.3%, making vaccination after an episode particularly important 7

Food and Administration

• Acyclovir tablets may be administered with or without food, as food does not affect absorption 1