What is a red sore under your lip?

There are a few possible conditions that could cause a red sore under your lip. Here are a few of the most common:

* Canker sore: This is a small, round or oval sore that can occur anywhere in the mouth, including under the lip. Canker sores are usually white or yellow in the center with a red border. They can be painful, especially when they are touched or irritated.

* Herpes simplex virus (HSV-1): This is a common virus that can cause cold sores. Cold sores are small, fluid-filled blisters that typically occur on the lips or around the mouth. They can be painful and contagious.

* Angular cheilitis: This is a condition that causes inflammation and cracking at the corners of the mouth. It can be caused by a variety of factors, including vitamin B deficiencies, dry skin, and yeast infections.

* Actinic cheilitis: This is a precancerous condition that is caused by sun exposure. It typically affects the lower lip and can cause redness, scaling, and cracking.

* Squamous cell carcinoma: This is a type of skin cancer that can occur anywhere on the body, including the lips. It can appear as a red, scaly patch or a firm, painless lump.

If you have a red sore under your lip, it's important to see a doctor or dentist to get a diagnosis and appropriate treatment.