Mouth Ulcers & Cold Sores

Cold sores vs mouth ulcers

They're different things. Cold sores appear on or around the lips, are caused by the herpes simplex virus, and respond best to antiviral creams like aciclovir used at the first tingle. Mouth ulcers are small, painful sores inside the mouth with many causes; treatments form a protective layer or numb the area to ease pain while they heal. Most clear on their own within a week or two.

Frequently Asked Questions

When should I apply cold sore cream?

Antiviral cold sore creams work best applied as early as possible — ideally at the first tingling or itching, before the blister fully forms.

How long do mouth ulcers last?

Most mouth ulcers heal within one to two weeks. See your dentist or doctor if an ulcer lasts longer than three weeks, is unusually large, or keeps recurring.

Are cold sores contagious?

Yes — avoid close contact like kissing and sharing utensils or towels while a cold sore is active, and wash your hands after applying cream.