Canker sores and cold sores are not the same thing. Canker sores occur inside the mouth, and cold sores (fever blisters) usually occur outside the mouth, usually on or near the lips.
A canker sore is a small ulcer with a white or gray base and red border. There can be one or a number of sores in the mouth. Canker sores are very common and recur often.
Canker sores, like all ulcers, are very difficult to treat. There is no proven technique that will eliminate ulcers or speed the recovery time once they appear. There are a few medications that will give temporary relief from the pain, but they need to be started as soon as symptoms appear. Over-the-counter topical anesthetics may provide relief. Canker sores usually heal in about a week or two.
A cold sore, which is also called fever blister and is caused by the “herpes simplex” virus, is composed by groups of painful, fluid-filled blisters that often erupt around the lips and sometimes under the nose or the chin.
Cold sores usually heal in about a week. Over-the-counter topical anesthetics may provide temporary relief and prescription antiviral drugs may reduce the occurrence of these kinds of viral infections.