Cold sores or fever blisters are caused by the herpes simplex virus and are usually easy to identify.
There is another condition which can cause ulcers inside the mouth known as Canker sores. Canker sores are not a form of herpes but they are often confused and mistaken for cold sores.
Canker sores are ulcerations, especially of the lip or oral mucosa and can be caused by acute stress, trauma to the area in your mouth, allergies, or by a reaction to a particular bacteria.
Canker sores are not considered to be contagious. Cold sores on the other hand are a type of herpes simplex virus and can be very contagious.
If you are experiencing ulcerations on or inside of your mouth please visit your doctor for a professional diagnosis. These two conditions can appear very similar and should not be self-diagnosed. Remember, cold sores are a form of the herpes simplex virus and are very contagious while canker sores are not contagious. You can see why it is important to get a diagnoses.
There are many products available to treat cold sores. Dynamiclear and Zovirax are two of the most effective topically applied products. Dynamiclear is nonprescription.