Blister from cold
A cold sore is a cluster of fluid-filled blisters usually caused by herpes simplex near the lip border.
The short answer
A cold sore is a cluster of fluid-filled blisters usually caused by herpes simplex near the lip border. It often tingles or burns before blistering, then crusts as it heals.
What is the direct answer?
What does this question mean?
The virus can remain in nerve tissue and reactivate after illness, sun exposure, stress, or local irritation. Similar-looking lesions can have other causes, especially when they occur inside the mouth.
What can you do next?
Keep the area clean, avoid picking it, wash hands after touching it, and do not share lip products, cups, or towels while it is active. Ask promptly about antiviral treatment when tingling begins.
When should you seek dental care?
Seek assessment if the lesion is severe, recurrent, spreading toward the eye, not healing, or affecting eating or drinking. A clinician should assess extensive lesions or sores in someone with reduced immunity.
What should you ask the dentist?
Ask whether the appearance and location fit a cold sore or another lesion. Ask whether a swab, antiviral medicine, or review of triggers is needed.
Frequently asked questions
Are cold sores contagious?
Yes, active lesions can spread through close contact and shared items.
Can a cold sore occur inside the mouth?
A lesion inside the mouth has several possible causes and should be assessed if persistent.