Herpes labialis

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  • Cause of the common "cold sore"
  • Sores typically heal within 2–3 weeks, but the herpes virus remains dormant in the facial nerve branches, following orofacial infection, periodically reactivating (in symptomatic people) to create sores in the same area of the mouth or face at the site of the original infection.
    • Frequency varies from rare episodes to 12 or more recurrences per year (typically 1-3 attacks per year)
    • The frequency and severity of outbreaks generally decreases over time.
  • Treatment does not affect dormant virus in nerve ganglions → recurrent disease remains possible

Clinical Features

Herpes labialis
  • typically umbilicated vesicles, painful, that unroof and crust over
  • typically localized to the vermillion border

Classic Phases

  • Prodromal (day 0–1): Tingling, itching, and reddening of the skin around the infected site
  • Inflammation (day 1): Swelling and redness
  • Pre-sore (day 2–3): Tiny, hard, inflamed papules and vesicles that may itch and are painfully sensitive to touch.
  • Open lesion (day 4): Vesicles break open and merge to create one big, open, weeping ulcer. May develop a fever and lymphadenopathy
  • Crusting (day 5–8): A honey/golden crust starts to form from the syrupy exudate.
  • Healing (day 9–14): New skin begins to form underneath the scab. A series of scabs will form over the sore (called Meier Complex), each one smaller than the last. Irritation, itching, and some pain are common.
  • Post-scab (12–14 days): A reddish area may linger at the site of infection.

Differential Diagnosis

Herpes Simplex Virus-1

Oral rashes and lesions


  • Clinical diagnosis, based on history and physical exam
  • Available laboratory studies (not required for diagnosis)[1]:
    • Viral culture (gold standard)
    • Direct immunofluorescence
    • Tzanck smear (poor specificity)


Anti-viral Treatment

Normal Host

  • Options:
    • Acyclovir
      • 400 mg PO 5x/day (q4hrs while awake) x 5 days, OR
      • 40-80mg/kg PO divided in 3-4 doses for 5-7 days, OR
        • Can also be used as a cream or oral suspension (swish and swallow)[1]
    • Famciclovir 500mg PO BID x 7 days, OR
    • Valacyclovir 2gm PO q12 x 1 day


  • Options:


  • Discharge if uncomplicated
  • Consider admission if immunocompromized, critically ill, or with large necrotic ulcers

See Also

External Links


  1. 1.0 1.1 Mohan RPS, Verma S, Singh U, Agarwal N. Acute primary herpetic gingivostomatitis. BMJ Case Reports. 2013;2013:bcr2013200074. doi:10.1136/bcr-2013-200074.