Blister on outside of lip

The outer lip is skin with a visible border, so a fluid-filled cluster differs from a blister on the moist inner lip. Tingling followed by grouped blisters that break and crust suggests herpes simplex, while a single lesion after friction, heat, or a product exposure has other possible causes.

Do not squeeze or peel the blister, keep hands clean, avoid sharing cups or lip products, and protect the area from rubbing. Note when tingling or swelling began and whether new blisters are appearing.

Arrange an assessment if it does not begin settling, repeatedly returns, becomes extensive, develops pus, or affects the eye. Prompt care is important for severe illness or reduced immunity.

Ask whether the lesion is a cold sore, an irritation blister, or another skin problem. Ask whether a swab or treatment is needed and how to prevent contact transmission.