I Have a Blister Inside My Cheek β€” Is It Cancer?

Finding a blister inside your cheek can make you worry. Here's what it typically means.

A blister inside the cheek is almost never cancer. In fact, it is one of the most common and least concerning findings in the mouth. Possible causes:

  • Trauma blister β€” from accidentally biting your cheek, eating something too hot, or irritation from braces or sharp foods. These heal quickly on their own
  • Blood blister β€” a dark red or purple blister caused by a pinch or minor injury, harmless
  • Mucocele β€” a clear or bluish blister from a blocked salivary gland, common on the lower lip and inner cheek
  • Pemphigus or pemphigoid β€” rare autoimmune conditions that cause blisters in the mouth; these need medical treatment but are not cancer
  • Herpes simplex β€” cold sores can appear inside the cheek but are more common on the lips

What to Look For

  • Usually not serious:
  • Clear, red, or dark purple fluid-filled blister
  • Appeared after eating, biting your cheek, or hot food
  • Heals within 1–2 weeks without treatment
  • Painful or tender (normal for a blister)
  • No other symptoms
  • Worth having checked:
  • Blister that does not heal after 2 weeks
  • Multiple blisters that keep coming back
  • Blisters with no clear cause that spread
  • Blisters accompanied by sores elsewhere on your skin
  • Painful blisters that make eating or drinking difficult

When to See a Doctor

  • See a dentist or doctor if:
  • The blister has not healed after 2 weeks
  • You have blisters on your skin as well as in your mouth
  • You have trouble eating or drinking because of the blisters
  • You have a fever or feel unwell along with mouth blisters

Clinical Guidance