See a doctor if a cold sore has not healed after two weeks, if outbreaks keep returning, if symptoms reach your eye, or if your immune system is weakened.
A typical cold sore tingles or itches first, blisters, crusts over, and clears in about 7 to 10 days without treatment. What changes the answer is how long it lasts, how often it returns, where it shows up, and your overall health. Prescription antiviral pills such as acyclovir or valacyclovir shorten an outbreak only when you start them at the first tingle, usually within 48 hours, so it helps to ask for a prescription before your next flare rather than during it. Keep the area clean, do not pick the scab, wash your hands after touching your face, and skip kissing and sharing cups, towels, or lip balm until the sore has fully crusted and healed.
When a cold sore needs a doctor
Common questions
When should you see a doctor for cold sores?
Most cold sores clear on their own in 7 to 10 days, so a visit is not always needed. Contact a doctor if a sore has not healed after two weeks, if outbreaks return often enough to bother you, if the area spreads or looks infected with pus and increasing redness, or if you have eczema or a weakened immune system from cancer treatment, transplant medicines, or HIV. Get same-day care for eye pain, light sensitivity, or blurred vision, since a herpes infection near the eye can affect sight. Seek emergency care for a baby under 3 months with a fever or blisters. Antiviral prescriptions work best started at the first tingle.