Allergies and Irritation
Sometimes, a lip sore is caused by an allergic reaction or irritation from things you use every day. Common causes include cosmetics, dental products, and certain foods. For example, some people might get contact dermatitis, which causes redness and swelling, after using a new lip balm or toothpaste. The best way to deal with this is to figure out what’s causing the problem and stop using it. Switching to hypoallergenic products can help your lips heal.
