Canker Sores Symptom: Causes, and the Best Treatment Options

Written by Medicover Team and Medically Reviewed by Dr Nikitha Reddy

Canker sores are small, painful ulcers that develop inside the mouth, often making eating, drinking, and talking uncomfortable. While generally harmless, they can be bothersome and may recur frequently. Understanding their symptoms, diagnosis, and treatment options can help manage and reduce their impact on daily life.

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Types of Canker Sores

Canker sores can be classified into three main types based on size and healing time:

Minor Canker Sores

Most common and smallest type
Less than 1 cm in diameter
Heal within 7–10 days without scarring.

Major Canker Sores

Larger and deeper, often more painful
It may take several weeks to heal.
Can leave scars

Herpetiform Canker Sores

Cluster of tiny sores (not caused by the herpes virus)
May merge into one large ulcer
Heal within 1–2 weeks.

Symptoms of Canker Sores

Canker sores often start with a tingling or burning sensation, followed by the appearance of a sore. Common symptoms include:

A small, round or oval sore with a white or yellow center and red border
Pain or sensitivity when eating, drinking, or brushing teeth
Tingling or burning sensation before the sore appears
Symptoms may include fever, swollen lymph nodes, or general malaise in severe cases.

Causes and Triggers of Canker Sores

While the exact cause of canker sores is not fully understood, several factors may trigger or contribute to their development:

Injury: Biting the inside of the cheek, braces, or sharp teeth
Stress: Emotional stress or anxiety
Nutritional Deficiencies: Low levels of iron, folic acid, or vitamin B12
Hormonal Changes: Menstruation or pregnancy-related changes
Food Sensitivities: Citrus fruits, spicy foods, or acidic foods
Allergic Reactions: To certain oral hygiene products (e.g., sodium lauryl sulfate)
Underlying Medical Conditions: Celiac disease, Crohn's disease, or immune system disorders

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When Should You See a Doctor for a Canker Sore?

Most canker sores are minor and heal without complications. However, consult a healthcare provider if:

The sore is unusually large or painful.
It doesn't heal within two weeks.
You experience frequent or recurring outbreaks.
There are signs of infection (pus, fever, spreading redness).
Difficulty eating, drinking, or speaking becomes severe.

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Diagnosis of Canker Sores

Canker sores are typically diagnosed through:

Physical Examination

A healthcare provider examines the mouth to identify the sore's size, location, and appearance.

Medical History

Discussing symptoms, triggers, diet, and family history helps determine the cause or frequency.

Blood Tests

If sores are frequent or severe, blood tests may be ordered to check for:

Nutritional deficiencies (iron, folic acid, B12)
Underlying systemic conditions like autoimmune disorders or infections

Biopsy (Rare)

In persistent or unusual cases, a small sample may be taken to rule out more serious conditions such as oral cancer or other types of ulcers.

Treatment Options for Canker Sores

While canker sores usually heal independently, treatments can ease pain and speed up recovery.

Topical Treatments

Over-the-counter gels or pastes (e.g., benzocaine, hydrogen peroxide)
Antiseptic mouthwashes to prevent infection
Prescription corticosteroid ointments for severe sores

Oral Medications

Pain relievers such as ibuprofen or acetaminophen
In severe cases, oral steroids or immune-modulating drugs may be prescribed.

Cauterization

Chemical or laser cauterization may be used to reduce healing time and pain.

Home Remedies for Canker Sores

Several natural remedies can help soothe the discomfort and promote the healing of canker sores:

Salt Water Rinse

Mix 1 teaspoon of salt in warm water and rinse your mouth to clean the sore and reduce inflammation.

Baking Soda Rinse

Dissolve 1 teaspoon of baking soda in water to neutralize acids and soothe irritation.

Honey Application

Apply raw honey to the sore for its antibacterial and healing properties.

Aloe Vera Gel

Use natural aloe vera gel directly on the sore to promote healing and reduce pain.

Chamomile Tea Compress

Place a cooled chamomile tea bag on the sore to reduce inflammation.

Avoid Trigger Foods

Avoid acidic, spicy, or salty foods that can worsen the pain or delay healing.

Ice Chips

Suck on ice chips to numb the area and reduce swelling.

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Frequently Asked Questions

To eliminate canker sores, use topical treatments, oral rinses, and over-the-counter pain relievers for immediate relief.

Canker sores usually heal in one to two weeks without treatment. Using home remedies will help you recover early. If you have more sores, it's better to visit the doctor nearby.

To prevent canker sores, avoid foods that irritate your mouth, manage stress, and maintain good oral hygiene.

A canker sore on gums is a small, painful ulcer that develops on the gum tissue.

Salt water helps canker sores by reducing inflammation and bacteria, promoting healing.

Applying salt directly to a canker sore can reduce bacteria but may cause intense pain. A better option is rinsing with a saltwater solution to promote healing without excessive discomfort.

A canker sore is a small, shallow ulcer inside the mouth, often white or yellow with a red border. It causes discomfort while eating or talking but is usually not contagious.

Canker sores can be caused by stress, mouth injuries, nutritional deficiencies (B12, iron, folic acid), hormonal changes, food allergies, spicy or acidic foods, and conditions like autoimmune disorders or gastrointestinal diseases.