Published: Jun 15, 2024

Mouth ulcers can make eating hard. They can make talking hurt. They can make brushing feel sharp.

Most mouth ulcers are not dangerous. Many heal on their own in 1 to 2 weeks. But some ulcers need medical or dental care.

For more simple health guides, visit our Health Hub, First Aid & Home Remedies Hub, Nutrition & Vitamins Hub, and Medical Tests & Screenings Hub.

Medical note: This article is for education only. It does not diagnose or treat mouth ulcers, mouth infections, immune disease, vitamin deficiency, or oral cancer. See a dentist or doctor if a mouth ulcer lasts more than 2 to 3 weeks, keeps coming back, is very large, bleeds, spreads, or comes with fever, weight loss, trouble swallowing, or a lump in the neck.

Quick Answer: What Are Mouth Ulcers?

Mouth ulcers are small sores inside the mouth.

They can appear on the:

• Inner cheeks
• Inner lips
• Tongue
• Gums
• Roof of the mouth
• Floor of the mouth

They may look white, yellow, gray, or red. They can sting or burn. They can hurt when you eat, drink, talk, or brush.

Many mouth ulcers heal without treatment. The primary goal is to reduce pain, protect the sore, and stop new ulcers from coming back.

Mouth Ulcers vs. Canker Sores vs. Cold Sores

These are not all the same.

Canker sores are a common type of mouth ulcer. They are not contagious.

Cold sores are different. They often form on the lip or around the mouth. They can spread to other people.

What Do Mouth Ulcers Feel Like?

A mouth ulcer may cause:

• Burning
• Stinging
• Sharp pain
• Pain when eating
• Pain when drinking
• Pain when brushing
• A sore spot on the tongue or cheek
• A round or oval sore
• A white or yellow center
• A red border

Some people feel tingling or burning before the ulcer appears.

Common Mouth Ulcer Causes

Mouth ulcers can happen for many reasons. Sometimes the cause is not clear.

Common causes and triggers include:

• Biting your cheek
• Biting your tongue
• Brushing too hard
• A sharp tooth
• Braces or dentures rubbing
• A broken filling
• Stress
• Lack of sleep
• Hormone changes
• Spicy foods
• Acidic foods
• Food sensitivity
• Toothpaste irritation in some people
• Low iron
• Low vitamin B12
• Low folate
• Some medicines
• Immune system conditions
• Digestive conditions such as inflammatory bowel disease or celiac disease

A single ulcer after biting your cheek is usually less worrying. Ulcers that keep coming back need more attention.

1. Mouth Injury

A small injury is one of the most common triggers.

This can happen from:

• Cheek biting
• Tongue biting
• Hard brushing
• Dental work
• Sharp food
• Braces
• Dentures
• A broken tooth
• A sharp filling

If one spot keeps getting ulcers, ask a dentist to check for rubbing, sharp edges, or bite problems.

2. Stress and Poor Sleep

Stress does not cause every ulcer. But it can be a trigger for some people.

You may notice ulcers after:

• Work stress
• Exams
• Poor sleep
• Travel
• Illness
• Emotional stress

A trigger diary can help you spot patterns.

3. Food Triggers

Some foods can sting an ulcer. Some may trigger ulcers in certain people.

Common problem foods include:

• Chili
• Hot sauce
• Citrus fruit
• Pineapple
• Tomatoes
• Vinegar foods
• Sharp crisps or chips
• Hard toast
• Very salty foods

Do not cut out many foods forever without a reason. First, track what happens.

4. Toothpaste or Mouthwash Irritation

Some people feel more mouth irritation with strong toothpaste or alcohol-based mouthwash.

Try a gentle toothpaste if ulcers keep coming back. Use an alcohol-free mouthwash if mouthwash burns.

Ask your dentist what is best for your teeth and gums.

5. Low Iron, Vitamin B12, or Folate

Repeated mouth ulcers can sometimes be linked with low iron, low vitamin B12, or low folate.

Other signs may include:

• Tiredness
• Pale skin
• Dizziness
• Shortness of breath
• Numbness or tingling
• Sore tongue
• Cracks at the corners

Do not guess. A blood test can help.

For nutrition support, visit our Nutrition & Vitamins Hub.

6. Medicines

Some medicines can cause mouth sores or make the mouth more sensitive.

This may happen with:

• Some pain medicines
• Some blood pressure medicines
• Some osteoporosis medicines
• Some cancer treatments
• Some immune medicines
• Some mouth sprays or inhalers, if used without rinsing

Do not stop prescribed medicine on your own. Ask your doctor or pharmacist.

7. Health Conditions

Repeated or severe ulcers may sometimes be linked with health conditions.

Examples include:

• Celiac disease
• Crohn’s disease
• Ulcerative colitis
• Behçet’s disease
• Lupus
• HIV
• Diabetes in some cases
• Low immune function
• Oral lichen planus

Most mouth ulcers are not from a serious illness. But repeated ulcers deserve a check.

How to Get Rid of Mouth Ulcers Fast

There is no safe instant cure for most mouth ulcers. But you can reduce pain and help the mouth heal.

Fast comfort steps include:

• Use warm salt water rinses.
• Drink cool fluids.
• Choose soft foods.
• Avoid spicy foods.
• Avoid acidic foods.
• Use a soft toothbrush.
• Do not pick at the ulcer.
• Use a protective oral gel if suitable.
• Ask a pharmacist about pain-relief mouth gel.
• Ask a dentist or doctor if ulcers are severe.

Small ulcers often heal with time. Treatment mainly helps with pain.

Safe Natural Relief for Mouth Ulcers

Natural care should be gentle. Do not burn the sore.

1. Salt Water Rinse

Mix half a teaspoon of salt in a cup of warm water. Swish gently. Spit it out.

Do not swallow it. Do not scrub the ulcer.

2. Cool Water or Ice Chips

Cold can numb pain for a short time.

Try:

• Cool water
• Ice chips
• Cold yogurt
• Cold smoothies that are not acidic

3. Soft Foods

Soft foods hurt less.

Try:

• Yogurt
• Oatmeal
• Scrambled eggs
• Soup that is not too hot
• Mashed potatoes
• Soft rice
• Banana
• Soft pasta

4. Gentle Brushing

Use a soft toothbrush. Brush slowly. Keep the mouth clean, but do not scrape the sore.

5. Trigger Diary

Write down:

• Foods eaten
• Stress level
• Sleep
• Toothpaste used
• Mouthwash used
• Menstrual cycle, if relevant
• Medicines
• Where the ulcer appears

This can help you find what starts outbreaks.

Pharmacy Treatments That May Help

Ask a pharmacist, dentist, or doctor what is safe for you.

Options may include:

• Protective pastes
• Pain-relief gels
• Numbing gels
• Antiseptic mouth rinses
• Alcohol-free mouthwash
• Anti-inflammatory mouth rinses
• Prescription steroid mouth rinse for severe cases
• Prescription medicine for repeated severe ulcers

Do not use adult numbing products on young children unless a healthcare professional says it is safe.

What to Eat With Mouth Ulcers

Choose foods that are soft and mild.

Good options include:

• Plain yogurt
• Milk
• Oatmeal
• Soft eggs
• Soft fish
• Soup that is warm, not hot
• Soft rice
• Soft pasta
• Avocado
• Banana
• Mashed vegetables
• Smoothies without citrus

Drink enough water. Dehydration can make the mouth feel worse.

Foods to Avoid Until It Heals

Some foods can sting and slow comfort.

Avoid or limit:

• Chili
• Spicy sauces
• Lemon
• Orange
• Grapefruit
• Pineapple
• Tomato sauce
• Vinegar
• Very salty snacks
• Hard chips
• Sharp toast
• Very hot drinks
• Alcohol

You can add foods back after the ulcer heals.

What Not to Put on a Mouth Ulcer

Some “fast cures” can make pain worse.

Do not put these directly on an ulcer:

• Undiluted hydrogen peroxide
• Lemon juice
• Vinegar
• Aspirin tablets
• Alcohol
• Harsh mouthwash
• Essential oils
• Tooth whitening products
• Very hot salt packs

If a remedy burns badly, stop. A painful burn is not healing.

How to Prevent Mouth Ulcer Outbreaks

You cannot prevent every ulcer. But you can reduce triggers.

1. Use a Soft Toothbrush

A soft brush can reduce injury. Brush gently.

2. Fix Sharp Teeth or Dental Rubbing

Ask a dentist to check braces, dentures, fillings, crowns, and sharp teeth.

3. Avoid Known Food Triggers

If a food clearly triggers ulcers, limit it.

4. Choose Gentle Mouth Products

If mouthwash burns, use alcohol-free options. Ask your dentist about toothpaste choices.

5. Manage Stress

Use small daily steps:

• Walk
• Breathe slowly
• Sleep on time
• Take breaks
• Write worries down
• Ask for support

6. Check for Deficiencies

If ulcers keep coming back, ask about blood tests for iron, B12, folate, and other checks.

7. Keep Good Oral Hygiene

Brush twice a day. Clean between teeth if your dentist advises. Keep dental checkups.

When Mouth Ulcers May Be More Serious

Most mouth ulcers are not cancer. But a sore that does not heal must be checked.

See a dentist or doctor if you have:

• An ulcer lasting more than 2 to 3 weeks
• A lump in the mouth
• A lump in the neck
• A red patch
• A white patch
• Bleeding that is not from brushing
• Pain that does not go away
• Trouble swallowing
• Trouble speaking
• Hoarse voice that does not go away
• Loose teeth without a clear reason
• Unexplained weight loss
• Ulcers that keep coming back

Do not panic. Many causes are not serious. But checking early is safer.

Mouth Ulcers in Children

Children can get mouth ulcers too.

Common causes include:

• Cheek biting
• Viral infections
• Hand, foot, and mouth disease
• Braces
• Hard foods
• Stress
• Not drinking enough

Call a healthcare professional if a child:

• Will not drink
• Has signs of dehydration
• Has a high fever
• Has many mouth sores
• Has a rash on hands or feet
• Has trouble breathing
• Has ulcers that last more than 2 weeks

Do not use adult mouth gels or numbing products in children unless a professional says it is safe.

Mouth Ulcers During Pregnancy

Some people get more ulcers during pregnancy because of hormone changes, stress, tiredness, or nutrient needs.

Do not start supplements or medicines without advice.

Ask a doctor, dentist, or pharmacist what is safe during pregnancy.

Mouth Ulcers and Braces or Dentures

Braces and dentures can rub the mouth and cause ulcers.

Helpful steps include:

• Ask your dentist to adjust the fit.
• Use orthodontic wax if advised.
• Keep dentures clean.
• Remove dentures at night if advised.
• Do not ignore repeated rubbing.

Repeated rubbing can keep an ulcer from healing.

Mouth Ulcers and Oral Cancer: How Are They Different?

Canker sores are often painful and shallow and heal within 1 to 2 weeks.

Oral cancer may not hurt at first. It may appear as a sore, lump, thick patch, red patch, white patch, or an area that does not heal.

You cannot always tell by looking.

See a dentist or doctor if a sore lasts more than 2 to 3 weeks or keeps getting worse.

How Doctors or Dentists Check Muth Ulcers

A dentist or doctor may:

• Look at the ulcer
• Ask how long it has been there
• Ask about pain and triggers
• Check your teeth and gums
• Check for sharp edges or rubbing
• Check your neck for lumps
• Ask about medicines
• Ask about diet
• Order blood tests if ulcers repeat
• Refer you for a biopsy if a sore looks unusual or does not heal

Tests may include iron, vitamin B12, folate, full blood count, celiac tests, or other checks based on your symptoms.

Questions to Ask Your Dentist or Doctor

• What type of mouth ulcer do I have?
• Could a tooth, filling, brace, or denture be rubbing?
• Do I need a blood test?
• Could I be low in iron, B12, or folate?
• Could my medicine be causing ulcers?
• What pain relief is safe for me?
• Should I change toothpaste or mouthwash?
• Do I need a prescription rinse?
• When should I come back if it does not heal?
• Do I need a biopsy or a specialist referral?

Simple 7-Day Mouth Ulcer Relief Plan

This is a comfort plan. It is not a cure for every cause.

Day 1: Remove Irritation

Avoid spicy, acidic, sharp, and hot foods. Use a soft toothbrush.

Day 2: Rinse Gently

Use a warm salt water rinse. Spit it out. Do not scrub the sore.

Day 3: Use Soft Foods

Eat yogurt, oatmeal, eggs, soup, soft rice, or a banana.

Day 4: Protect the Sore

Ask a pharmacist about a protective gel or paste.

Day 5: Check Triggers

Write down stress, sleep, foods, toothpaste, and where the ulcer is.

Day 6: Check Dental Rubbing

If the ulcer is near a sharp tooth, brace, or denture, book a dental check.

Day 7: Watch Healing

If it is not improving, is very painful, or keeps coming back, ask a dentist or doctor.

FAQ

What causes mouth ulcers?

Mouth ulcers can be caused by cheek biting, hard brushing, braces, dentures, sharp teeth, stress, poor sleep, spicy or acidic foods, food sensitivity, low iron, low vitamin B12, low folate, medicines, or health conditions.

How long do mouth ulcers last?

Many mouth ulcers heal within 1 to 2 weeks. See a dentist or doctor if an ulcer lasts more than 2 to 3 weeks or keeps coming back.

How can I get rid of mouth ulcers fast?

You cannot always make them vanish fast, but you can reduce pain. Use salt water rinses, soft foods, cool drinks, a soft toothbrush, and a protective mouth gel if suitable.

Are mouth ulcers contagious?

Canker sores are not contagious. Cold sores are different and can spread to other people.

What should I avoid with mouth ulcers?

Avoid spicy foods, acidic foods, sharp snacks, very hot drinks, alcohol, harsh mouthwash, and direct lemon, vinegar, or aspirin on the sore.

Can stress cause mouth ulcers?

Stress can trigger mouth ulcers in some people. It is not the only cause. A diary can help you find your personal triggers.

Can vitamin deficiency cause mouth ulcers?

Repeated ulcers can sometimes be linked with low iron, vitamin B12, or folate. A blood test can help find out.

When should I worry about a mouth ulcer?

Get checked if an ulcer lasts more than 2 to 3 weeks, is very large, bleeds, keeps returning, comes with a lump, red or white patch, trouble swallowing, fever, or weight loss.

Can mouth ulcers be a sign of cancer?

Most mouth ulcers are not cancer. But a sore that does not heal, a lump, a red or white patch, or ongoing mouth pain should be checked by a dentist or doctor.

What is the best treatment for mouth ulcers?

The best treatment depends on the cause. Small ulcers may need only gentle care. Severe or repeated ulcers may need mouth rinses, protective pastes, prescription medicine, dental fixes, or blood tests.

Related Reading

• Health Hub
• First Aid & Home Remedies Hub
• Nutrition & Vitamins Hub
• Medical Tests & Screenings Hub
• Digestive Health & Gut Hub
• Cancer Awareness & Prevention Hub
• Healthy Lifestyle Roadmap: 14 Practical Tips for Better Health
• Effect of Unhealthy Lifestyle: Warning Signs, Health Risks, and How to Reset
• Health Screening 101: Simple Guide to Medical Tests
• Calcium Deficiency: Causes, Symptoms, and How to Prevent It

Key Takeaway

Mouth ulcers are painful sores inside the mouth. Most are harmless and heal within 1 to 2 weeks.

Common triggers include mouth injury, hard brushing, braces, dentures, stress, spicy foods, acidic foods, and low iron, B12, or folate.

Fast relief means gentle care: salt water rinses, soft foods, cool drinks, soft brushing, and protective mouth gels when suitable.

Do not use harsh “fast cures” like lemon, vinegar, alcohol, or aspirin on the sore.

See a dentist or doctor if an ulcer lasts more than 2 to 3 weeks, keeps coming back, bleeds, is very large, or comes with a lump, red or white patch, trouble swallowing, fever, or weight loss.

Sources

• NHS — Mouth Ulcers
• NHS Inform — Mouth Ulcer
• NIDCR — Fever Blisters and Canker Sores
• MedlinePlus — Canker Sores
• MedlinePlus Medical Encyclopedia — Canker Sore
• Mayo Clinic — Canker Sore Symptoms and Causes
• Mayo Clinic — Canker Sore Diagnosis and Treatment
• Cleveland Clinic — Mouth Ulcer
• NHS — Mouth Cancer Symptoms
• NIDCR — Oral Cancer

Adel Galal

Health & wellness writer with 30+ years of experience in nutrition, fitness, and healthy aging. Founder of NextFitLife.com — evidence-based health guidance.