Usually not: most cold sores heal on their own within one to two weeks, though a few situations do need prompt medical care.
Cold sores come from herpes simplex virus, most often type 1, which stays in the body and can reactivate after illness, stress, sun exposure, or hormonal changes. The answer changes when the virus reaches places it should not go, such as the eye, broken eczema skin, or a newborn, and when your immune system is suppressed by medication or illness. Prescription antiviral pills like acyclovir or valacyclovir shorten an outbreak most when you start them at the first tingle, before blisters form. Keeping the area clean, using lip balm with sunscreen, and not touching or picking the sore lowers the chance of spreading it to others or to your own eyes. Cold sores are contagious through kissing, shared drinks, utensils, towels, and oral sex, including in the days before a blister appears.
When to worry
Common questions
Is cold sores serious?
Most cold sores are not serious. They typically blister, crust over, and heal within one to two weeks without scarring, and many people manage them with over the counter creams and cool compresses. The virus stays in your body afterward and can come back. A cold sore does need prompt medical attention in specific situations: pain, redness, or a sore near the eye, a spreading rash if you have eczema, any blister in a baby under 3 months, sores that last longer than two weeks, or an outbreak in someone with a weakened immune system. Antiviral pills such as acyclovir or valacyclovir work best when started at the first tingle.