Mouth sores (sometimes called mouth ulcers) can be identified by their location. Canker sores only occur inside the mouth, whereas cold sores form on the outside of your mouth, usually on the skin near your lip.

Cold sores are caused by a virus and are therefore contagious. Canker sores, on the other hand, are instigated by a variety of factors but cannot be spread.

Most mouth sores heal on their own. Usually, they are harmless, unless your immune system has been compromised by a chronic illness such as cancer or HIV/AIDS.

If you have a mouth sore that does not go away for several weeks, or if your symptoms are recurring, you should contact your doctor. Some sores can be indicators of mouth or neck cancer, or they may be the result of an infection.

Canker Sores

Canker sores can develop on the soft tissue inside your mouth. They do not form on your gums or the roof of your mouth, though they may develop along the base of your gums. You’ll often find canker sores on the inside of your lip or the wall of your mouth.

Canker sores start as a raised bump and then turn into an open sore. These sores make it difficult to eat or drink, and they also make brushing and flossing a challenge. Thankfully, canker sores don’t last long, typically any more than two weeks. They should go away on their own, though there are some strategies you can use to monitor the pain:

  1. Use a topical gel or patch. This helps protect the sore from spicy, hot, or acidic foods and other irritants, i.e. if the affected area is bumped or jostled.
  2. Take vitamin supplements. Canker sores have been linked with a B-12 vitamin deficiency. Consider taking supplements if you are having routine troubles with canker sores.
  3. Avoid irritating foods. These can be acidic foods like tomatoes or citrus fruits, spicy dishes, hot beverages and foods with a rough or crunchy texture.
  4. Use mouth rinses. You can mix water with a teaspoon of salt for a basic salt rinse. However, medicated mouthwashes may be more effective. You should be able to purchase a medicated rinse in your local pharmacy without a prescription.

Canker sores have been linked with vitamin and sleep deficiencies, stress, and hormone changes (often menstruation or pregnancy). They also often result from injuries in the mouth, such as burns from hot foods or cuts from orthodontic appliances or sports.

Canker sores are also caused by food allergies. They are often paired with chronic illnesses like celiac or inflammatory bowel disease. People with drier mouths have a higher risk of developing canker sores.

Cold Sores

Cold sores form along the outside of your mouth, usually near your lip. They can also form inside your mouth or nostrils.

These sores can be caused by the herpes simplex virus HSV-1. This is not the same as HSV-2, genital herpes, though the two illnesses are related. Once you contract HSV-1, it will live in your system throughout your lifetime. The virus will remain dormant, but you may periodically experience flare-ups due to stress, hormone changes, or a lowered immune system from illness or surgery.

Cold sores have several stages. First, you may feel tingling or itching around your mouth before a small blister develops. These blisters may spread to other spots around your mouth and will eventually burst before they ooze and crust over. Cold sores are very contagious, so you should avoid touching the affected area for fear of spreading it.

Cold sores usually heal on their own within seven to ten days. You shouldn’t need to contact your doctor unless your symptoms persist longer than usual. If your immune system is compromised by cancer treatment or HIV/AIDS, you need to take action against cold sores immediately to avoid serious complications.


If you have cold sores, you should consider:

  • Antiviral ointments. Topical creams like acyclovir and penciclovir can shorten recovery times, but they must be used as soon as you experience itching or tingling, otherwise, they may not help.
  • Antiviral medications. Valacyclovir, acyclovir, and famciclovir are commonly used to shorten your recovery time for cold sores. People with routine outbreaks will often turn to these medicines.
  • Topical ointments to relieve discomfort. While these creams cannot speed up your recovery, they will soothe pain and keep the sore moisturized. Be sure to wash your hands after applying the ointment and do not share the medication with others.
  • Painkillers. Ibuprofen and Tylenol can help relieve discomfort.
  • Avoiding contagion. To avoid spreading the virus to others, do not share food or utensils and avoid physical contact near the mouth. Wash your hands with soap and warm water if you touch the affected area. Be careful not to touch other sensitive areas of your body where the virus could easily spread, such as the eyes or genitals.