How long does a cold sore last?
Last updated September 3, 2026.
Up to 2 to 3 weeks from tingle to healed skin - and the blister days are the most contagious. The stages run tingle, blister, weep, crust, heal. MedlinePlus notes oral herpes spreads most easily from an active sore, so no kissing or shared lip products during an outbreak. Antivirals work best started at the first tingle, before the blister forms - frequent sufferers can keep a supply on hand.
What to do
- Treat at the tingle. Antivirals started before the blister forms shorten the episode the most.
- Quarantine the sore, not yourself. No kissing, shared lip balm, towels, or razors during the outbreak.
- Hands off. Touching the sore spreads virus to eyes and other people - wash hands after any contact.
- Escalate the exceptions. Eye involvement, sores past two weeks, or any outbreak while immunocompromised: see a doctor.
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