A cold sore is contagious from the moment symptoms like tingling or itching begin, and remains contagious until the sore is fully healed, which typically takes about two weeks. The highest contagiousness occurs when the cold sore blisters are fluid-filled and actively oozing, but even after the sore has scabbed over, it can still potentially spread the virus until the scab falls off and the skin completely heals. Avoiding close contact during this entire period is advised to prevent transmission.
Key Points on Contagiousness Duration
- Contagious from first symptoms (tingling, itching) to complete healing.
- Peak contagiousness when blisters burst and ooze fluid.
- Contagiousness decreases after scab formation but is not zero until scab falls off.
- Healing usually takes two weeks (up to 10-15 days).
- Virus can spread through saliva, skin contact, and sharing objects.
Recommendations to Avoid Spread
- Avoid kissing and close contact.
- Do not share towels, dishes, or utensils.
- Wash hands regularly after touching the sore.
- Avoid oral sex and contact sports during an outbreak.
In summary, a cold sore is no longer contagious once it has completely healed and the skin has returned to normal, which typically happens after about two weeks.
