Mouth sores

Mouth sores can develop for several reasons, and they usually go away on their own. Our doctors help you pinpoint their cause and manage your symptoms.

What are mouth sores?

Mouth sores are bumps or blisters in or around your mouth. They can develop in several spots, including the:

• Bottom of your mouth
• Gums
• Inner cheeks
• Lips
• Roof of your mouth
• Tongue

Cause of mouth sores

Mouth sores can have several causes. They can develop from tissue irritation, such as if you:

• Accidentally bite your lip, tongue or cheek
• Burn your mouth from a hot food or drink
• Chew tobacco
• Eat too many acidic foods
• Have a sharp or broken tooth
• Have braces
• Wear poorly fitting retainers or dentures

They can also result from certain illnesses or health problems, such as:

• Allergic reaction
• Autoimmune disease
• Herpes simplex virus
• Infections, such as cold or flu
• Mouth cancer
• Vitamin deficiency or hormone changes
• Weakened immune system

Symptoms of mouth sores

Mouth sores can look and feel different depending on the type. They may look like small red, yellow or white bumps. They may be filled with fluid or dry and blistery.

Depending on the type, a mouth sore may cause:

• Itching
• Pain and discomfort, especially when eating, drinking or talking
• Redness and swelling around the area
• Tenderness
• Tingling or burning sensation

Most mouth sores go away naturally within two weeks of appearing.

Types of mouth sores

Mouth sores range from harmless bumps that go away on their own to signs of a larger health problem. Common types of mouth sores include canker sores, cold sores and oral thrush.

Canker sores

Canker sores, also called aphthous ulcers, develop as white or yellow bumps. They usually have a red outer ring.

You may have one or several small canker sores at the same time. Canker sores aren’t contagious and usually go away within a couple of weeks.

Cold sores

Cold sores, also called fever blisters or oral herpes, are contagious mouth sores. They’re caused by an infection with the herpes simplex virus. This virus can live in your body for years, but it doesn’t always cause symptoms.

Cold sores develop as blisters and crust over with time. They commonly appear on or around your lips, on your gums or on the roof of your mouth.

You may develop a sore throat, fever and swollen glands before cold sores appear. The area may also feel tender and have a tingling or burning sensation.

Oral thrush

Oral thrush is a fungal infection that develops in your mouth. It happens when a type of yeast called Candida, which lives naturally in your mouth, grows out of control.

The infection creates a white coating or white patches in your mouth. It also causes underlying redness and bleeding.

Mouth sore diagnosis

Your doctor will ask about your symptoms and medical history. Then they’ll examine the mouth sore.

Your doctor can diagnose most mouth sores based on their appearance and your symptoms. You may need a blood test or mouth swab if your doctor thinks a health issue may be causing your mouth sores.

Some conditions, such as perioral dermatitis, cause bumps and red rashes around your mouth that may look similar to mouth sores. Your doctor will rule out this and other conditions to determine what treatment you may need.

Mouth sore risk factors

Mouth irritation can increase your chance of developing canker sores. You may face a higher risk if you:

• Chew tobacco
• Eat a lot of acidic food
• Wear braces, retainers or dentures

Certain illnesses, infections and other factors can also make you more likely to develop mouth sores, including:

• Autoimmune diseases
• Fever
• Hormone changes, such as during your period or pregnancy
• Infections, including from the herpes simplex virus
• Stress
• Sun exposure
• Vitamin deficiencies
• Weakened immune system, whether from an illness or from medical therapies like chemotherapy

Mouth sore prevention

Talk to your doctor about what may be causing mouth sores if you get them regularly. If irritation is leading to canker sores, you may be able to prevent them by:

• Brushing your teeth with a softer-bristled toothbrush
• Chewing slowly to avoid biting your lip, cheek or tongue
• Reducing stress in your daily life
• Taking vitamin supplements if you have a deficiency
• Waiting for hot food and drinks to cool down before consuming them

To prevent cold sores and their spread, make sure you keep your lips moisturized and apply sunscreen to them before sun exposure. You should avoid:

• Having oral sex if you have an active cold sore, especially if it looks blistery
• Sharing food or drinks if you or someone else has a cold sore
• Touching cold sores

Treating canker sores

Your doctor may recommend several ways to help prevent and treat canker sores. Some therapies may ease symptoms and prevent more mouth irritation, including:

• Applying ice to the mouth sore
• Gargling with salt water or cold water
• Using over-the-counter medication, such as acetaminophen, Orabase, Blistex or Campho-Phenique
• Using gels, creams, pastes or mouthwash specially made to reduce swelling and other symptoms