NewMouth is reader supported. We may earn a commission if you purchase something using one of our links. Advertising Disclosure.
In this article
If you have a small, painful sore in your mouth, it may be a mouth ulcer. Also known as canker sores or aphthous ulcers, mouth ulcers commonly appear as shallow lesions inside your mouth.
Unlike cold sores, most mouth ulcers aren’t contagious, and they usually go away on their own within two weeks. Let’s discuss more about mouth ulcers, their symptoms, causes, and when you should see a doctor.
What Does a Mouth Ulcer Look Like?
Mouth ulcers look like round or oval sores on the soft tissues inside your mouth. They usually appear on the lips or cheeks but can also develop:
On the sides of the tongue
Beneath the tongue
Around the gums
On the upper palate
A mouth ulcer can be white, yellow, grey, or red and may appear swollen. You can have a single ulcer or many, and they’re typically small and shallow.
Three types of mouth ulcers are categorized by size and how long they last:
Minor aphthous ulcers — These are smaller than 5 mm and heal within 7 to 14 days. 80% of mouth ulcers are minor.
Major aphthous ulcers — These are larger than 5 mm and heal slowly over several weeks or months. Major ulcers often cause scarring.
Herpetiform ulcers — Multiple ulcers that appear as a cluster of 10 to 100 pinpoints and usually heal within one month.
The primary symptom of a mouth ulcer is the appearance of a small sore inside your mouth. Other symptoms can include:
Pain that worsens when eating spicy, sour, or salty foods
Loss of appetite due to mouth pain
Discomfort while brushing your teeth
Swelling around the sore
Mouth ulcer symptoms may worsen during periods of stress, illness, or lack of sleep.
What Causes Mouth Ulcers?
Although mouth ulcers are common, the exact cause remains unknown. Factors contributing to mouth ulcers include:
Minor oral tissue trauma — Examples include accidentally biting the inside of the cheek, sharp edges on dental appliances or teeth, or sports injuries.
Food sensitivities — Coffee, chocolate, eggs, nuts, and spicy or acidic foods are common culprits.
Nutritional deficiencies — Not getting enough iron, folate (folic acid), zinc, or vitamin B-12 may increase the risk of mouth ulcers.
Sodium lauryl sulfate — Some toothpaste and mouth rinses contain this ingredient.
Allergies — Certain bacteria can cause an allergic reaction in your mouth.
Hormonal changes — These often occur during puberty, pregnancy, and menopause.
Health conditions — Mouth ulcers are linked to medical conditions like diabetes, inflammatory bowel disease, and immune disorders.
Stress and smoking can make you more prone to developing mouth ulcers. We also recommend paying attention to any foods that seem to trigger your ulcers. Common triggers include:
Acidic fruits (citrus, tomatoes)
Spicy foods
Chocolate
Coffee
Difference Between a Mouth Ulcer and a Cold Sore
Canker sores and cold sores are not the same. Mouth ulcers appear inside your mouth. They’re caused by various factors like vitamin deficiency, injury, and irritation.
Cold sores are blisters that appear on your lips or around the mouth. They’re caused by a virus and are contagious.
When to See a Doctor for a Mouth Ulcer
See a doctor or dentist if you experience any of the following:
Canker sores that last three weeks or more — Mouth ulcers typically last one to two weeks. If they last longer than this, see a doctor.
Unusual sores — If you are used to getting canker sores repeatedly, you know what typical sores look like. If you notice a different type developing in your mouth, take extra caution.
Sores that spread rapidly — This may be a sign of oral cancer.
Extremely large or painful sores — Severe pain or unusually large sores can signify a more serious condition.
A fever accompanies them — Mouth ulcers are not usually accompanied by a fever, so if they are, consider medical attention.
Bad breath — The bad breath may be caused by food debris that remains in your mouth for a long time. If you leave this untreated for a long time, an infection can develop.
We recommend seeing your doctor or dentist if you have a mouth ulcer or cluster of sores that are unusually large, extremely painful, or last longer than three weeks. A mouth sore that doesn’t go away or grows larger may be a sign of oral cancer.
How are Mouth Ulcers Diagnosed?
A mouth ulcer is diagnosed through a simple visual exam. However, further tests may be needed if you have other worrisome symptoms.
If your oral health expert cannot identify the origin of your mouth ulcers, or if the ulcers do not respond to standard treatments, you may need a biopsy of the ulcer and some surrounding tissue.
A biopsy is a process that involves the removal of a tissue sample for examination under a microscope and diagnosis.
Effective Treatments for Mouth Ulcers
Mouth ulcers can make eating, drinking, and even talking uncomfortable. While they often heal on their own within a week or two, knowing how to manage symptoms and prevent future outbreaks can make a big difference.
Listen In Q&A Format
Mouth Ulcers: Causes, Symptoms & Treatment
NewMouth Podcast
When a mouth ulcer strikes, several over-the-counter products and home remedies can provide relief:
Topical anesthetics — Gels or liquids containing benzocaine or lidocaine can temporarily numb the area, reducing pain.
Antiseptic mouthwashes — Rinsing with an antiseptic mouthwash can help prevent infection and promote healing.
Protective pastes — Applying a paste made from baking soda and water or magnesia milk can create a protective barrier and soothe the ulcer.
Saltwater rinse — Gargling with warm salt water can reduce inflammation and promote healing.
Ice chips — Sucking on ice chips can numb the area and provide temporary relief.
Honey — Applying honey to the ulcer can help soothe and promote healing due to its antibacterial properties.
Diet changes — Avoid acidic or spicy foods that can irritate the ulcer and delay healing.
Some people find relief by applying a small amount of aloe vera gel to the ulcer. Staying well-hydrated can help prevent dry mouth, which can sometimes contribute to ulcers.
If OTC treatments or home remedies don’t work, it’s best to see your healthcare provider for treatment suggestions. Some options they may talk to you about include:
Prescription-strength topical corticosteroids
Oral medications
Cauterization of the ulcer
Don’t hesitate to seek professional help if you have concerns about persistent or recurring ulcers.
All NewMouth content is medically reviewed and fact-checked by a licensed dentist or orthodontist to ensure the information is factual, current, and relevant.
We have strict sourcing guidelines and only cite from current scientific research, such as scholarly articles, dentistry textbooks, government agencies, and medical journals. This also includes information provided by the American Dental Association (ADA), the American Association of Orthodontics (AAO), and the American Academy of Pediatrics (AAP).
