Mouth Pain: Reasons, Causes and When to Worry

What mouth pain feels like and what it can mean

Mouth pain covers several different feelings, and the type of pain is often the best clue to the reason:

• Sharp, stinging pain when eating acidic or spicy food usually comes from an ulcer or raw patch of lining.
• Throbbing, constant pain that keeps you awake, especially when lying down, points to an infected tooth.
• Short, sharp twinges with cold, hot or sweet food suggest a cavity, a crack or exposed tooth roots.
• Burning across the tongue or palate with no visible cause suggests burning mouth syndrome, a deficiency or dry mouth.
• Electric-shock jabs lasting seconds, triggered by touching the face or brushing, suggest trigeminal neuralgia.
• A dull ache in the jaw and teeth on waking points toward clenching or grinding.

A sign of mouth pain in a baby or young child is usually behavior rather than words: refusing food or drink, drooling more, crying when feeding, or rubbing the face.

Mouth pain causes by location

Where the pain sits narrows down the reason quickly.

Common reasons for mouth pain

Mouth ulcers (canker sores)

Aphthous ulcers are the single most common reason for a sore mouth. They are round or oval, shallow, white or yellow in the middle with a red rim, and appear on the soft inner lining of the cheeks, lips, tongue or floor of the mouth. They are not contagious. Most are smaller than 1 cm and heal in 7 to 14 days. Triggers include minor injury, stress, hormonal changes, and some toothpastes containing sodium lauryl sulfate. Frequent ulcers can be linked to iron, folate or vitamin B12 deficiency, celiac disease or inflammatory bowel disease.

Tooth decay and cracked teeth

A cavity is painless until it reaches the inner dentin, then causes sensitivity to sweet, hot and cold. If decay reaches the pulp (the nerve), the pain becomes spontaneous and lingering. A cracked tooth hurts sharply when you bite and release, often on one particular cusp. See toothache for more on tooth pain patterns.

Dental abscess

An abscess is a pocket of pus at the root tip or in the gum. It causes severe, throbbing pain that may spread to the ear, jaw or neck, a tooth that feels "high" or tender to touch, a swollen gum or face, and sometimes fever. A dental abscess will not go away without dental treatment, and it can spread.

Gum disease

Gingivitis makes gums red, swollen and prone to bleed. It is rarely very painful. Advanced periodontitis can cause aching gums, loose teeth and gum abscesses. Wisdom teeth that are partly through the gum can cause pericoronitis: a painful, swollen flap of gum at the back of the mouth, often with a bad taste and pain on opening wide.

Injuries and burns

Biting the cheek or tongue, burns from hot drinks or pizza, sharp food such as chips, a broken tooth edge and new braces or dentures all cause localized pain. These heal within 1 to 2 weeks once the source of rubbing is removed.

Viral infections

• Cold sores and primary herpes: recurrent cold sores occur on the lip. A first herpes infection, common in young children, causes herpes simplex stomatitis: fever and many painful ulcers on swollen, bleeding gums.
• Hand, foot and mouth disease: small painful ulcers at the back of the mouth with spots on the hands and feet, mainly in children under 5.
• Shingles: a band of painful blisters on one side of the palate or face.

Oral thrush

A yeast overgrowth that causes creamy white patches which wipe off to leave red, sore areas, or a burning red mouth. It is common in babies, denture wearers, people using inhaled steroids, people with diabetes and anyone taking antibiotics. See oral thrush.

Dry mouth

Saliva protects the mouth lining. Dry mouth from medicines (antidepressants, antihistamines, blood pressure tablets), radiotherapy, Sjögren's syndrome or mouth breathing causes soreness, burning and a higher risk of decay and thrush.

Less common but important causes

• Burning mouth syndrome: a persistent burning, usually of the tongue tip, in a mouth that looks normal. It is most common in women after menopause and often worsens through the day. Doctors diagnose burning mouth syndrome only after ruling out deficiencies, thrush, dry mouth, diabetes and reflux.
• Nutritional deficiencies: low iron, B12, folate or zinc can cause a sore, smooth, red tongue and cracks at the mouth corners.
• Lichen planus: an immune condition causing white lacy streaks or painful raw areas on the cheeks and gums.
• Medicines and cancer treatment: chemotherapy and radiotherapy commonly cause mucositis, a painful, widespread inflammation of the lining.
• Nerve pain: trigeminal neuralgia causes brief, severe, shock-like pain in the cheek, jaw or teeth.
• Referred pain: sinusitis can make the upper back teeth ache, and jaw joint disorders cause pain in front of the ear. Angina occasionally causes pain felt in the jaw.
• Oral cancer: usually painless at first. Any ulcer, lump or red or white patch lasting more than 3 weeks, especially in smokers or heavy drinkers, needs examination to rule out oral cancer.

Symptoms that come with mouth pain

When to worry about mouth pain

Mouth pain itself is rarely dangerous. Worry when it comes with spreading swelling, fever, difficulty swallowing or breathing, or when a sore fails to heal. Infections of the floor of the mouth can rapidly block the airway, and an abscess in an upper tooth can spread toward the eye. Any sore present for 3 weeks or more should be seen by a dentist or doctor, whatever it looks like.

Can a dentist diagnose mouth pain?

Yes. A dentist is usually the best first stop for mouth pain, because most causes involve the teeth, gums or lining. A dentist will:

1. Ask where the pain is, what triggers it (hot, cold, biting), how long it lasts and whether it wakes you.
2. Examine the teeth, gums, tongue, cheeks, palate and floor of the mouth, and feel the neck glands.
3. Tap and test teeth with cold to see which nerve is inflamed.
4. Take dental X-rays to find decay, abscesses and bone loss.
5. Take a swab or biopsy of a persistent sore or patch.

See a primary care doctor if the soreness involves the whole mouth, comes with other body symptoms, or keeps returning. Blood tests can check blood count, iron, B12, folate and blood sugar.

How to relieve mouth pain

Home care

• Warm salt-water rinse: half a teaspoon of salt in a cup of warm water, swished and spat out several times a day.
• Avoid triggers: spicy, acidic, salty and very hot foods, crunchy snacks, alcohol and tobacco.
• Soft, cool foods such as yogurt, smoothies and mashed vegetables. Drink through a straw if sores are at the front.
• A soft toothbrush and toothpaste without sodium lauryl sulfate if you get frequent ulcers.
• Keep hydrated, especially children with viral mouth sores.

Over-the-counter treatments

• Pain relievers: acetaminophen (paracetamol) or ibuprofen. Follow the label dose. Do not give aspirin to children or teenagers, and do not place aspirin against the gum, which burns the tissue.
• Protective and numbing gels: barrier pastes cover an ulcer while it heals. Benzocaine gels give short relief for adults but should not be used in children under 2.
• Antiseptic mouthwash: chlorhexidine reduces infection in ulcers and sore gums. It can stain teeth if used for long periods.

Medical and dental treatment

• Fillings, root canal treatment or extraction for decay and abscesses. Antibiotics are added when infection spreads or you have a fever, but they do not replace dental treatment.
• Professional cleaning and gum treatment for periodontitis.
• Antifungal medicine for thrush and antiviral medicine for severe herpes.
• Steroid mouthwashes or pastes for severe or recurrent ulcers and lichen planus.
• Correcting any deficiency, and reviewing medicines that dry the mouth.

Preventing mouth pain

• Brush twice a day with fluoride toothpaste and clean between teeth daily.
• See a dentist regularly, so decay is found before it reaches the nerve.
• Wear a mouthguard for contact sports and a night guard if you grind your teeth.
• Avoid tobacco and limit alcohol, which raise the risk of gum disease and oral cancer.
• Rinse your mouth after using a steroid inhaler.

Frequently asked questions

What is the most common reason for mouth pain?

Mouth ulcers (canker sores) and dental problems such as decay and gum disease are the most common reasons. Minor injuries like burns and cheek bites come next. The location helps: pain in one tooth suggests a dental cause, while sores on the soft lining usually mean an ulcer, injury or infection.

What is a sign of mouth pain in a child?

Young children often show mouth pain by refusing food or drink, drooling, crying while feeding, putting hands in the mouth or being irritable. Look for ulcers, swollen gums or spots on the hands and feet. Seek care if your child will not drink or passes little urine.

Can a dentist diagnose mouth pain?

Yes. Dentists diagnose most mouth pain, because it usually comes from teeth, gums or the mouth lining. They examine the whole mouth, test teeth and take X-rays. If they suspect a medical cause such as a deficiency or immune condition, they refer you to a doctor or oral medicine specialist.

Why does my whole mouth hurt?

Pain throughout the mouth usually comes from a viral infection, thrush, dry mouth, a reaction to a new toothpaste or medicine, or cancer treatment. Burning without visible changes suggests burning mouth syndrome or a vitamin deficiency. A doctor can check with an examination and blood tests.

How long should mouth pain last before I see a dentist?

See a dentist within a few days for any tooth pain, because decay and infection do not heal on their own. Sores and minor injuries should improve within 1 to 2 weeks. Any sore, lump or patch that is still there after 3 weeks needs a professional check.

Can stress cause mouth pain?

Yes, indirectly. Stress is a common trigger for canker sores and for clenching or grinding the teeth, which causes jaw and tooth aching. Stress and anxiety are also linked with burning mouth syndrome. The pain is real and treatable, but other causes should be ruled out first.