Mouth problems range from common tooth decay and bleeding gums to infections and suspicious ulcers. Many conditions share similar symptoms, so appearance alone may not identify the cause. Persistent pain, swelling, bleeding, colour changes or sores should be assessed by a dentist or appropriate healthcare professional.
Reviewed by Dr. Manish Pandey, BDS. This guide is educational and is not a diagnosis.
Quick warning signs
Seek urgent dental care for severe uncontrolled pain, rapidly increasing swelling, fever with dental swelling, pus, trauma, or difficulty opening your mouth. Difficulty breathing or swallowing, swelling around the eye or neck, or uncontrolled bleeding requires emergency medical help. Have any mouth ulcer lasting more than three weeks, unexplained red or white patch, or persistent lump examined promptly.
1. Dental cavities (tooth decay)
Decay develops when plaque bacteria use sugars and starches to produce acids that repeatedly remove minerals from teeth. Early damage may appear as a chalky white area; a developed cavity can cause sensitivity, pain, food trapping or a visible hole. Advanced decay can infect the pulp and form an abscess.
Treatment depends on depth and may include fluoride support for a non-cavitated early lesion, a filling, root canal treatment or extraction. Learn more in our dental cavities guide.
2. Gingivitis and periodontitis
Gingivitis commonly causes red, swollen gums that bleed during brushing or interdental cleaning. It is usually reversible when plaque and tartar are controlled. Periodontitis is more advanced gum disease involving loss of the bone and attachment supporting teeth; warning signs can include gum recession, deep pockets, loose teeth or bite changes.
Do not wait for pain—gum disease can progress quietly. See our evidence-based guide to gingivitis symptoms and treatment.
3. Tooth sensitivity
A brief sharp sensation from cold, heat, sweets or brushing may occur when dentine becomes exposed through enamel wear or gum recession. Sensitivity can also come from decay, a cracked tooth, a leaking restoration, whitening products or recent dental work.
Desensitising toothpaste may help some cases, but continuing or one-sided sensitivity needs a dental examination. Severe lingering pain after temperature changes can indicate inflammation inside the tooth rather than simple sensitivity.
4. Chipped or cracked teeth
Teeth may chip or crack from trauma, biting hard objects, decay, large fillings or grinding. A small enamel chip may feel rough without pain; deeper damage may cause pain when biting, temperature sensitivity or a visible split. A crack can extend beneath the gum even when little is visible.
Save any broken fragment, avoid chewing on the area and arrange dental care. Facial trauma, uncontrolled bleeding, a displaced permanent tooth or a tooth knocked out requires urgent assessment.
5. Dental abscess
An abscess is a collection of pus caused by infection, often from an infected tooth or gum pocket. Symptoms can include severe throbbing pain, pain on biting, a gum boil, bad taste, facial swelling, fever or tender lymph nodes.
An abscess does not reliably disappear without treating its source. Dental treatment may involve drainage, root canal therapy, periodontal treatment or extraction. Antibiotics are used selectively when infection is spreading or systemic signs are present; they do not replace definitive dental care.
6. Mouth ulcers (canker sores)
Aphthous ulcers are painful, round or oval sores that occur inside the lips, cheeks or elsewhere on movable oral tissue. They are not the same as cold sores and are not contagious. Minor ulcers often heal within one to two weeks. Trauma, stress, nutritional deficiency and some systemic conditions or medicines may contribute.
Avoid irritating spicy or acidic foods and use gentle oral hygiene. Seek assessment for unusually large, frequent or severe ulcers, ulcers with other illness, or any sore lasting more than three weeks.
7. Cold sores
Cold sores are caused by herpes simplex virus and usually develop as clusters of fluid-filled blisters on or around the lips. Tingling or burning may occur before the blister appears. Unlike aphthous ulcers, cold sores are contagious, particularly while active.
Avoid kissing, oral contact and sharing lip products, utensils or towels during an outbreak. Antiviral treatment may shorten symptoms when started early; ask a pharmacist or clinician what is appropriate. Seek care for severe, frequent or eye-area symptoms, or if immunity is reduced.
8. Oral thrush
Oral thrush is an overgrowth of Candida yeast. It may produce creamy white patches that can wipe away and leave a red or sore surface, altered taste, burning or cracks at the mouth corners. Risk is higher with dentures, recent antibiotics, inhaled corticosteroids, dry mouth, diabetes or weakened immunity.
White patches have several possible causes, so confirmation is important. Treatment may include an antifungal medicine plus addressing denture hygiene, inhaler technique, dryness or glucose control. Read the full oral thrush guide.
9. Dry mouth
Persistent dry mouth, or xerostomia, means there is not enough saliva to keep the mouth comfortable. It can make speaking, chewing and swallowing difficult and increases the risk of decay and fungal infection. Common causes include medicines, dehydration, Sjögren’s disease, diabetes and head-and-neck cancer treatment; it is not simply a normal part of ageing.
Sip water, avoid tobacco and excess alcohol, and consider sugar-free gum if safe for you. Do not stop prescribed medicine without medical advice. A dentist or doctor can investigate the cause and recommend saliva-support and fluoride measures.
10. Persistent patches, ulcers or lumps
Most mouth changes are not cancer, but early oral cancer can resemble a harmless ulcer or patch. Warning signs include an ulcer lasting more than three weeks, unexplained red or white patch, a lump in the mouth or neck, persistent mouth or throat pain, unusual bleeding, numbness, hoarseness, or difficulty chewing, swallowing or speaking.
Tobacco and alcohol increase risk, and some oropharyngeal cancers are associated with human papillomavirus (HPV). Do not diagnose a suspicious lesion from a photograph. Arrange an in-person examination; earlier assessment matters.
What symptoms can overlap?
| Symptom | Possible causes |
|---|---|
| Toothache | Decay, crack, pulp inflammation, abscess, gum disease |
| Bleeding gums | Gingivitis, periodontitis, trauma, medicine or systemic factors |
| White patch | Thrush, friction, inflammatory disorders, precancerous change |
| Bad breath | Plaque, gum disease, dry mouth, infection, tongue coating |
| Facial swelling | Dental infection, salivary disease, trauma or other medical causes |
This overlap is why a symptom list cannot replace examination, gum measurements, vitality tests, X-rays or laboratory investigation when indicated.
How to reduce common mouth problems
- Brush twice daily with fluoride toothpaste and clean between teeth every day.
- Limit frequent sugary food and drinks, particularly between meals.
- Do not use tobacco and limit alcohol.
- Attend dental check-ups based on your individual risk.
- Clean dentures daily and remove them as advised.
- Discuss persistent dry mouth and medication side effects with a clinician.
- Use a mouthguard for contact sport and a professionally advised appliance when grinding is diagnosed.
- Check your mouth periodically and seek assessment for persistent changes.
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