Cold Sores (Herpes Labialis)
Cold sores (herpes labialis) are recurrent oral HSV-1 outbreaks, managed per AAFP guidance on common oral lesions and the Cochrane review of herpes labialis treatment.
Symptoms
A tingling or burning sensation (prodrome) followed by small, painful, fluid-filled blisters that cluster, burst, and crust over on or around the lips, typically healing within 7-10 days.
Causes and risk
Herpes simplex virus type 1, reactivated by triggers such as sun exposure, stress, illness, or menstruation; the virus stays latent in nerve tissue between outbreaks and remains contagious even when no sore is visible.
How it is evaluated
Diagnosis is usually clinical from the classic blister pattern and prodrome; viral culture or PCR is used when the diagnosis is unclear.
Treatment
Antivirals are most effective when started at the first tingle: valacyclovir 2 g every 12 hours for one day, or famciclovir 1500 mg as a single dose, per FDA labeling (valacyclovir) and (famciclovir). Daily suppressive therapy is an option for frequent outbreaks (roughly six or more a year).
When to seek care
Sores near the eye, spreading beyond the lip, or occurring in someone immunocompromised need prompt evaluation -- immunocompromised patients follow separate guidance from the NIH/OARAC HIV opportunistic infection guidelines.