Angular cheilitis on one side

The affected corner may look red, cracked, crusted or softened by saliva. Opening the mouth can reopen the split and cause stinging.

A one-sided patch can reflect saliva collecting unevenly, lip licking, rubbing, dental appliances or a tooth shape that changes how the lips meet. Yeast or bacteria can grow in already damaged, damp skin, so appearance alone does not identify the cause.

Other problems, including contact irritation, a cold sore or a persistent skin lesion, may resemble angular cheilitis. Location on one side does not by itself make the problem dangerous, but persistence deserves examination.

Gently rinse away food, pat the corner dry and apply a plain fragrance-free barrier ointment. Avoid licking, picking, strongly flavoured lip products and foods that noticeably sting the split. Check whether a mask, denture or other item repeatedly rubs that side.

Do not assume every crack needs an antifungal, antibiotic or steroid. Using the wrong product may irritate the skin or obscure the diagnosis; a pharmacist or clinician can match treatment to the suspected cause.

Arrange medical review if the area keeps returning, fails to settle with gentle barrier care, spreads beyond the corner or develops marked swelling, pus, worsening crusting or increasing pain. Seek prompt help for rapidly spreading redness, fever, difficulty swallowing or swelling that affects breathing.

A clinician may inspect the mouth, teeth and any appliances, and may consider infection, eczema, contact allergy or nutritional and health factors when episodes recur.

Ask what features support angular cheilitis rather than another lip condition, whether an appliance or product is contributing, which barrier product is suitable and whether a targeted medicine is needed.