What are the treatment guidelines for shingles in Canada?

Shingles Treatment Guidelines in Canada

Oral antiviral therapy (acyclovir, valacyclovir, or famciclovir) should be initiated within 72 hours of rash onset as the primary treatment for shingles to reduce acute pain and accelerate healing. 1, 2

Antiviral Therapy

• First-line medications:

  • Acyclovir: 800 mg orally 5 times daily for 7 days 2
  • Valacyclovir: 1000 mg orally 3 times daily for 7 days 3
  • Famciclovir: 500 mg orally 3 times daily for 7 days 3

• Timing: Treatment is most effective when started within 72 hours of rash onset, though benefits may still be observed with later initiation 3

• Special populations:

  • Severe cases requiring hospitalization: Acyclovir 5-10 mg/kg IV every 8 hours for 5-7 days 1
  • Immunocompromised patients: May require longer treatment duration and closer monitoring 1
  • Acyclovir-resistant cases: Consider foscarnet 40 mg/kg IV every 8 hours until clinical resolution 1

Dosage Adjustments for Renal Impairment

For acyclovir, adjust dosage based on creatinine clearance:

• CrCl >25 mL/min: 800 mg every 4 hours, 5 times daily
• CrCl 10-25 mL/min: 800 mg every 8 hours
• CrCl 0-10 mL/min: 800 mg every 12 hours 1

Pain Management

• Acute pain:

  • Mild pain: Acetaminophen or NSAIDs
  • Moderate to severe pain: May require stronger analgesics 1

• Postherpetic neuralgia (PHN):

  • First-line: Gabapentin (titrate to 2400 mg per day in divided doses)
  • Alternatives: Tricyclic antidepressants (e.g., amitriptyline), pregabalin, SNRIs
  • Topical options: Capsaicin (8% patch or cream), lidocaine patches 1, 4

Corticosteroids

• Short-term corticosteroids (e.g., prednisolone starting at 40 mg daily with taper over 3 weeks) may provide modest benefits in reducing acute pain
• However, they do not reduce the incidence of postherpetic neuralgia 5
• Use with caution due to potential adverse effects, especially in patients with diabetes, hypertension, or immunosuppression 5

Prevention of Transmission

• Avoid close contact with susceptible individuals (especially immunocompromised persons, pregnant women without history of chickenpox, and newborns) until lesions have crusted 6
• Cover lesions to minimize risk of transmission

Vaccination

• Herpes zoster vaccine is recommended for adults aged 50 years and older to prevent future outbreaks 7
• Not indicated for treatment of acute shingles or prevention of PHN in patients with active shingles 7

Follow-up and Monitoring

• Re-examine patients 3-7 days after treatment initiation to assess response
• Monitor for complete resolution of lesions and evaluate for complications 1
• If no improvement is seen, consider:
  • Incorrect diagnosis
  • Antiviral resistance
  • Immunocompromised status
  • Poor medication adherence 1

Special Considerations

• Ophthalmic zoster: Requires prompt referral to an ophthalmologist to prevent serious complications 2
• HIV-infected patients: May require longer courses of therapy and closer monitoring 1
• Pregnant patients: Acyclovir can be used safely during pregnancy 1

Common Pitfalls to Avoid

1. Delaying treatment beyond 72 hours (though treatment may still be beneficial)
2. Inadequate pain management during acute phase and follow-up
3. Failing to recognize and promptly refer ophthalmic involvement
4. Not adjusting antiviral dosages in patients with renal impairment
5. Overlooking the need for vaccination in eligible individuals to prevent future episodes