Canker Sore or Cold Sore?

In or out? That's the first question to ask when you're trying to figure out whether you have a canker sore or a cold sore. If it's inside your mouth, it's most likely a canker sore; outside, probably a cold sore.

The two may seem similar, but the similarity ends with the fact that both are connected with the mouth and both cause pain and discomfort. So knowing which one you have is the first step to knowing how it's caused and how to treat it.

 Cold sores, also known as fever blisters, are tiny, clear, fluid-filled blisters that form around the mouth and are caused by the herpes simplex virus (usually type 1, or HSV-1) living inside your nerve tissue. Cold sores usually do not last longer than two weeks. However, the sores are highly contagious and tend to recur when the virus is reactivated by a trigger such as stress, sunlight, fever or illness.

 Most cold sores are mild and do not require treatment. Antiviral medications can reduce the frequency, duration and severity of outbreaks. Medications with a numbing agent, such as benzyl alcohol, can help alleviate a cold sore's burning, itching and pain. Emollients can reduce cracking and soften scabs. Applying aloe vera balm three times a day to the cold sore also can help fight the infection and enhance healing.

Like cold sores, canker sores, also known as aphthous ulcers can be quite painful and often recur. While cold sores are caused by a virus, the formation of a canker sore is unknown and may be triggered by multiple factors such as stress, food allergies or a weakened immune system. A canker sore forms in the soft tissues of your mouth and is not contagious.

Pain from a canker sore generally lessens in a few days, and the sores usually heal without treatment in about a week or two. If sores are large, painful, or persistent, your dentist may prescribe an antimicrobial mouth rinse, a corticosteroid ointment, or a prescription or over-the-counter solution to reduce the pain and irritation.