Because cold sores and canker sores can look so much alike, and both types of sores are usually seen either on or inside the mouth, it is easy to get the two confused. Cold sores and canker sores are actually two completely different types of conditions, with different causes. Cold sores are caused by the herpes simplex virus type 1, but canker sores are not a result of contact with the herpes virus. Here are the details about cold sores and canker sores, and how to tell them apart.

Cold Sores

Cold sores, also called fever blisters, develop as a result of the herpes simplex virus type 1. The herpes virus stays in the body permanently once contracted, but will usually only result in an outbreak sporadically. It is very common to come in contact with the herpes simplex type 1 virus during childhood. While the herpes virus may not cause an immediate outbreak, certain conditions may cause cold sores to erupt. If a person who is carrying the herpes simplex virus type 1 is exposed to excess sunlight, has any type of injury to the mouth, has a cold or other illness, or even has any type of general stress, a cold sore outbreak may occur.

Typically, a cold sore eruption will begin as a single or group of fluid filled sores up to around 3 mm wide. The cold sores will break open as they come to maturation, and will then form a crust over the sore. As the crust begins to fall away, new pink skin underneath will be revealed. Under normal circumstances a cold sore will heal within about one week to 10 days. Cold sores can be painful, but the pain is not generally excessive. Many people find that they experience itching, especially as the sores begin to heal.

Canker Sores

Canker sores may look similar to cold sores in some cases, but the two types of sores are actually unrelated. While the case of cold sores is known to be the herpes simplex virus type 1, the cause of canker sores is not known. Canker sores are actually a type of ulcer called a recurrent aphthous ulcer, and they appear inside the mouth. Canker sores are most often seen on the tongue, the lower regions of the mouth, or the inner lining of the cheeks and lips. It is known that canker sores do not result from infection, and that they may arise as a result of an inflammation.

Canker sores range in size from very small, around cold sore size, up to quite large. Canker sores can be very painful and may interfere with a person's ability to drink, eat or even talk normally when they are quite large and developed. In the majority of cases, canker sores will heal on their own within about two weeks. In some cases a topical medication, such as a product containing benzocaine, can be used to provide pain relief. Saline rinses are also used sometimes to help soothe pain and inflammation.