Fever blister corner of mouth
A fever blister is a grouped, fluid-filled sore caused by herpes simplex virus, often appearing on the lip edge or mouth corner.
The short answer
A fever blister is a grouped, fluid-filled sore caused by herpes simplex virus, often appearing on the lip edge or mouth corner. It may tingle or burn before blisters form, then crust as it heals.
What is the direct answer?
What does this question mean?
The mouth corner can split from saliva, irritation, or angular cheilitis, which may resemble a fever blister. A clinician distinguishes these by the lesion pattern, location, recurrence, and examination.
What can you do next?
Keep the area clean, avoid picking the crust, and wash hands after touching it. Do not share lip products, cups, or towels while a blister is present, and ask promptly about antiviral treatment if it is new or recurring.
When should you seek dental care?
Seek assessment if the sore is near the eye, spreads widely, lasts unusually long, or occurs with severe illness or a weakened immune system. A persistent crack at the mouth corner also needs evaluation for another cause.
What should you ask the dentist?
Ask whether the appearance fits herpes labialis or another condition, whether a swab is useful, and when treatment should begin. Ask how to protect the eye and reduce transmission at home.
Frequently asked questions
Is every mouth-corner crack a fever blister?
No. Saliva irritation, angular cheilitis, trauma, and other conditions can look similar.
Should I pop the blister?
No. Popping can injure the skin and spread fluid to nearby tissue.