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Overview
Cold sores often start with tingling.
They're contagious until healed.
When to get medical care
Call 911Not an emergency.
Get care todayNear the eye. Weak immune system.
See a doctor soonFrequent outbreaks.
Causes
Caused by herpes simplex virus.
OwieClear has pages on 1 condition that can cause cold sore or blister on the lip. Each shows how soon to get care.
Common causes
- Cold soresOften treated at home
Small, painful blisters on or around the lips caused by a common virus.
What you can do at home
- Don't touch it.
- Avoid kissing.
Medicines
Antiviral creams or pills.
At the doctor
Diagnosed by exam.
Questions you may be asked
- Outbreaks
The exam
A lip exam.
Tests
- None
Prevention
Prevent outbreaks.
- Use lip balm with sunscreen
Check your symptoms
Most symptoms have more than one possible cause. The symptom checker looks at all of your symptoms together, plus your age, and shows how soon to get care.
Sources
Last updated 2026-11-13.