What is the treatment for shingles with secondary cellulitis in a patient on losartan (angiotensin II receptor antagonist) and furosemide (loop diuretic) with no known drug allergies (NKDA)?

Treatment for Shingles with Secondary Cellulitis in a Patient on Losartan and Furosemide

The treatment for shingles with secondary cellulitis requires a combination of antiviral therapy for shingles (10-14 days of systemic antiviral medication) plus appropriate antibiotics for cellulitis (5-6 days of antibiotics active against streptococci and potentially MRSA). 1, 2

Antiviral Therapy for Shingles

• Initiate systemic antiviral therapy immediately:
  • Famciclovir 500 mg twice daily for 7 days OR
  • Valacyclovir 1000 mg three times daily for 7-10 days OR
  • Acyclovir 800 mg five times daily for 7-10 days 1, 3

Famciclovir may be preferred due to its more convenient dosing schedule (twice daily versus five times daily for acyclovir) with comparable efficacy in cutaneous healing of herpes zoster 3.

Antibiotic Therapy for Secondary Cellulitis

• For non-purulent cellulitis (most likely streptococcal):

  • First-line: Cephalexin 500 mg orally four times daily for 5-6 days 2

• If MRSA is suspected (purulent drainage, prior MRSA infection, penetrating trauma):

  • Clindamycin 300-450 mg orally four times daily for 5-6 days OR
  • Trimethoprim-sulfamethoxazole PLUS a beta-lactam antibiotic (to cover streptococci) 2

Monitoring and Follow-up

• Daily follow-up until definite improvement is noted
• Monitor for:
  1. Skin lesions developing firm, adherent crusts with no discharge
  2. No new lesions appearing in the preceding 48 hours
  3. Resolution of cellulitis (decreased erythema, swelling, and pain)
  4. No evidence of systemic symptoms (fever, chills) 1, 2

Special Considerations for Patient on Losartan and Furosemide

• No significant drug interactions between the recommended antimicrobials and losartan or furosemide that would require dose adjustments
• Monitor renal function as both losartan and furosemide can affect kidney function 4
• Be aware that rarely, furosemide has been associated with severe drug reactions including DRESS syndrome, though this is extremely uncommon 5

Hospitalization Criteria

Consider hospitalization if:

• No improvement within 24-48 hours of outpatient therapy
• Progressive infection despite appropriate treatment
• Systemic toxicity or significant comorbidities
• Immunocompromised state 2

Adjunctive Therapies

• Pain management with acetaminophen or NSAIDs as needed
• Some evidence suggests NSAIDs may help hasten resolution of cellulitis-related inflammation 6
• Keep affected area clean and dry
• Elevate affected limb if applicable to reduce edema

Prevention of Recurrence

• Maintain good personal hygiene
• Keep skin lesions covered with clean, dry bandages until fully healed
• Avoid sharing personal items during active infection 2

Common Pitfalls to Avoid

1. Delaying antiviral therapy (should be started within 72 hours of rash onset for maximum effectiveness)
2. Using trimethoprim-sulfamethoxazole as a single agent for cellulitis (may not adequately cover streptococci)
3. Failing to recognize when outpatient therapy is failing and hospitalization is needed
4. Confusing Sweet syndrome with cellulitis (consider this if treatment fails) 7