Herpes Labialis

Herpes labialis (cold sore) is a vesicular eruption of the lips and perioral skin caused mostly by herpes simplex virus type 1, which establishes latency in the trigeminal ganglion. Primary infection is often silent or presents as gingivostomatitis in childhood.

• Transmission is by saliva and direct contact, including from asymptomatic shedders.
• Reactivation triggers: sunlight, fever, menstruation, trauma, dental work, stress, immunosuppression.
• Higher frequency, severity and duration in HIV infection, malignancy, transplantation and malnutrition.

Prodrome of tingling, burning or itch for 6 to 24 hours, then grouped vesicles on an erythematous base at the vermilion border, which rupture, ulcerate and crust over 7 to 10 days.

• Primary episode: fever, painful gingivostomatitis, cervical lymphadenopathy, drooling and poor oral intake in children.
• Differential diagnosis: impetigo, angular cheilitis, contact dermatitis, aphthous ulcer, herpes zoster of the maxillary division, hand foot and mouth disease, erythema multiforme, squamous cell carcinoma of the lip, syphilitic chancre.
• Complications: bacterial superinfection, eczema herpeticum, herpetic keratitis, herpetic whitlow, erythema multiforme, disseminated infection and oesophagitis in immunosuppression, dehydration in primary disease.

Clinical in typical cases.

• HSV PCR of vesicle fluid or swab for atypical, severe or immunosuppressed presentations; viral culture or direct immunofluorescence where PCR is unavailable.
• HIV testing for severe, prolonged or recurrent disease; glucose.
• Tzanck smear is insensitive and not specific.

Antivirals shorten the episode only when started at the prodrome or within 72 hours of onset.

• Supportive: simple analgesia (paracetamol 1 g up to four times daily), cool compresses, petroleum jelly to prevent cracking, avoid kissing and sharing utensils or towels until crusted, hand washing, avoid touching the eyes, adequate oral fluids.
• Pharmacological: episodic oral therapy with valaciclovir 2 g twice daily for 1 day, or famciclovir 1500 mg as a single dose, or aciclovir 400 mg five times daily for 5 days. Topical aciclovir 5 percent cream five times daily for 5 days or penciclovir 1 percent cream every 2 hours while awake for 4 days. Primary gingivostomatitis: aciclovir 200 mg five times daily for 5 to 7 days (children under 2 years 100 mg, older children 200 mg), with oral rehydration. Immunosuppressed: aciclovir 400 mg five times daily for 7 to 10 days; severe or disseminated disease, aciclovir 5 mg/kg IV every 8 hours until improving, then oral therapy.
• Procedures: none; drain and dress large secondarily infected lesions.
• Special groups: pregnancy, aciclovir or valaciclovir are acceptable for symptomatic episodes; neonates exposed to maternal lesions need urgent paediatric review; renal impairment, reduce the aciclovir dose by creatinine clearance; HIV, treat early and optimise antiretroviral therapy.
• Red flags: lesions near the eye or on the nose tip, eczema herpeticum, widespread vesicles, fever with confusion, inability to drink, immunosuppression, lesions not healing after 2 weeks.
• Follow-up: review if not healed in 10 to 14 days; assess recurrence frequency and sun protection.