Constantly Biting the Inside of Your Cheek? Causes, Warning Signs, and When to Worry

Almost everyone bites the inside of the cheek once in a while, especially when chewing too fast or talking while eating. That occasional “ouch” usually heals in a few days and is rarely serious.

But if you constantly bite or chew your inner cheek – sometimes without even noticing – it may be a sign of a deeper issue:

• A chronic habit linked to stress or anxiety
• A misaligned bite or sharp tooth
• Teeth grinding and jaw problems
• A body-focused repetitive behaviour that needs attention

In medical and dental language, chronic cheek biting is called morsicatio buccarum. It is a condition where repeated biting or nibbling injures the lining of the cheek and creates ragged, white, or sore patches inside the mouth.^[1–3]

The good news: most cheek biting is benign and treatable. The important part is knowing when it is just a nuisance and when it might be a warning sign that needs prompt evaluation.

Morsicatio buccarum describes chronic irritation of the cheek lining from repeated biting or chewing. It is common enough that some studies find cheek-biting lesions in a noticeable number of adults at any given time.^[3,4]

Typical features include:

• Rough, shredded, or ragged white patches on the inner cheek
• Often on both sides, along the line where the upper and lower teeth meet (occlusal plane)
• Mixed areas of whiteness, redness, and sometimes small ulcers
• Loose bits of soft tissue that sometimes peel away^[3,5,6]

Many people are only vaguely aware of biting their cheeks; some are completely unaware until a dentist points out the lesions.^[6]

Chronic cheek biting is now recognised as a body-focused repetitive behaviour in mental health classifications. It can be related to stress, anxiety, boredom, or obsessive–compulsive tendencies and often overlaps with habits like lip biting, nail biting, or skin picking.^[1,3,7,8]

Signs that your cheek biting behaves like a body-focused repetitive behaviour:

• You do it automatically while reading, driving, working, or scrolling on your phone
• You feel a brief sense of relief or “release” when you bite
• You feel guilty, embarrassed, or ashamed afterward^[7,9]

Most people have more than one contributing factor. Understanding the mix in your case helps guide treatment.

Stress and anxiety are major drivers of awake cheek biting. When the nervous system is “on edge,” many people clench their teeth, brace their jaw, or chew the inner cheek without realising it.^[7,10,11]

Key points:

• Cheek biting often intensifies during exams, deadlines, relationship stress, or emotional distress
• It becomes part of a habit loop: trigger → tension → cheek bite → brief relief → guilt → more tension
• Because it is partly soothing in the short term, the brain learns to repeat it, even though it is harmful in the long run.

Sometimes the structure of the teeth and bite is the main issue.

• A misaligned bite (malocclusion) can cause the inner cheek to bulge between the teeth during chewing or talking, making it easier to bite accidentally.^[12,13]
• Jagged fillings, broken teeth, or sharp edges after dental work can repeatedly catch and tear the cheek lining.
• Ill-fitting dentures, crowns, or orthodontic appliances that shift the way teeth come together may also contribute.^[3,5,14]

If you noticed cheek biting after a filling, crown, or denture, or if it always happens in the same spot against a sharp tooth, a dental alignment or smoothing problem is very likely.

Cheek biting is commonly linked with bruxism – repeated teeth grinding or clenching during sleep or while awake.^[10,11,15]

• People who grind or clench often have other mouth habits like tongue thrusting or cheek chewing.
• Tight jaw muscles and disorders of the temporomandibular joint can change the way the teeth move, increasing the chance of catching cheek tissue.
• Night-time bruxism can cause cheek biting during sleep, and you may wake up with sore cheeks or ridges along the bite line.^[10,14]

Some cheek biters report that they bite most when:

• Reading or watching screens for a long time
• Driving long distances
• Working at a desk, especially when concentrating intensely

In these situations, cheek biting functions like nail biting: a mindless, repetitive behaviour that keeps the mouth busy.

In a smaller group of people, cheek biting may be associated with:

• Learning difficulties or neurodevelopmental conditions
• Certain rare genetic syndromes
• Severe psychiatric conditions where self-injury is part of the picture^[3,5,6]

In such cases the behaviour can be more intense and damaging, and professional support is essential.

When the inner cheek is repeatedly rubbed or crushed against the teeth, the mucosa responds by thickening its surface layer. This is called frictional keratosis – a reactive white lesion caused by chronic mild trauma.^[4,16]

Typical features:

• White or greyish patch on the cheek along the bite line
• Slightly rough, thickened surface
• Often bilateral (on both cheeks) in people who habitually chew both sides

Dental studies suggest that frictional keratosis from chronic mechanical irritation is very common and, importantly, does not carry a risk of becoming cancer on its own.^[16,17,18]

If you bite deeply or pull tissue away:

• Painful sores and ulcers can form on the inside of the cheek
• Repeated healing and re-injury can leave a thickened ridge or white line called linea alba along the bite level^[9,19]

Chronic cheek biting can also cause:

• Redness and small tears in the mucosa
• Swelling that makes the cheek more likely to get caught again
• Emotional distress and embarrassment about the appearance of the inner cheek^[9,19,20]

In a few cases, habitual cheek biting may even begin to shift tooth positions slightly over time, especially if the pressure is always in one direction.^[20]

Most cheek biting lesions are harmless frictional changes, but it is critical not to ignore certain red flags.

You should seek prompt dental or medical evaluation if you notice:

• A mouth sore that does not heal within about two or three weeks, or keeps getting worse, is a major warning sign. Persistent ulcers can occasionally indicate precancerous or cancerous changes in the oral mucosa.^[21–24]

While frictional keratosis is benign, there is another condition called leukoplakia – a persistent white patch that cannot be rubbed off and is not explained by another disease. Leukoplakia can be precancerous.^[25–27]

You should be checked if you notice:

• A white, red, or red-and-white patch that stays for weeks and does not improve
• Thickened or raised areas on the inner cheek that feel different from the surrounding tissue

Health organisations emphasise that persistent white, red, or dark patches, lumps, or thickened regions in the mouth deserve professional examination.^[25–28]

Seek help if you experience:

• Difficulty chewing or swallowing
• Pain that radiates to the ear or jaw
• Trouble opening the mouth fully

These may reflect more serious underlying problems that are not just simple cheek biting.^[21,26]

• A new lump, mass, or hard area inside the cheek, or swelling on one side of the face, needs evaluation to rule out infection, salivary gland problems, or oral cancer.^[21,23,26]

This is a very common fear.

Recent reviews of the scientific evidence suggest that chronic mechanical trauma by itself does not appear to be a direct cause of oral cancer.^[17,29]

Key points:

• Frictional keratosis from cheek biting is considered a reactive lesion with no malignant potential when the trauma stops.^[16,17]
• However, if a suspicious white or red patch in the mouth does not go away after removing the source of trauma and giving time to heal, it must be evaluated for other causes such as leukoplakia or early cancer.^[25–28]

So:

• Occasional cheek biting is not a cause of cancer.
• Chronic friction alone probably does not turn normal tissue into cancer.
• Persistent, unexplained changes in the mouth always deserve a professional check-up.

First, rule out simple mechanical issues:

• Ask your dentist to look for sharp edges, broken fillings, or high points after recent dental work.
• Have your bite assessed for significant misalignment or tooth crowding.^[12,13,24]

Treatment may include:

• Smoothing sharp edges or polishing restorations
• Adjusting new crowns or dentures
• Orthodontic treatment in cases of significant malocclusion

If you grind or clench your teeth:

• A custom occlusal guard or mouth guard worn at night can protect the cheeks and teeth.
• Jaw relaxation techniques, physical therapy, and stress management can reduce bruxism intensity.^[10,11,15]

Some case reports also describe using specially designed acrylic appliances that cover biting surfaces to protect the cheek and help break the habit.^[5,17]

Because cheek biting is often partly behavioural, habit-breaking strategies are very useful:

• Awareness training:
  • Keep a small log of when and where you bite your cheek (while driving, at the computer, during arguments, etc.).
  • This helps you see patterns and triggers.
• Competing responses:
  • When you notice the urge, gently close your teeth together and press your tongue to the roof of your mouth instead.
  • Some people chew sugar-free gum briefly to redirect the urge away from the cheeks (if your dentist approves).
• Environmental cues:
  • Place a small sticker on your laptop or steering wheel to remind you to check jaw tension and cheek position.

Behavioural therapies such as habit reversal training and cognitive behavioural therapy have shown benefit for body-focused repetitive behaviours, including cheek and lip biting.^[5,17,22]

While you are working on the underlying causes:

• Use a bland saltwater rinse or alcohol-free mouthwash to keep the area clean.
• Avoid spicy, very hot, acidic, or rough foods that sting the sore region.
• Ask your dentist or doctor about protective gels or coatings that can temporarily shield the ulcer.

This helps reduce pain and swelling, which in turn lowers the chance of re-biting the same area.

Because stress and anxiety are central triggers for many people:

• Build simple stress-relief habits: walking, stretching, deep breathing, or brief relaxation breaks during the day.
• If cheek biting is tied to intense worry, perfectionism, or compulsive tendencies, consider speaking with a mental health professional.

Health resources emphasise that chronic cheek biting can be a sign of underlying mental health concerns, and therapy can help reduce both the biting and the distress around it.^[7,22,24]

You should book an appointment if:

• You cannot control the biting, and your cheeks are frequently sore or bleeding
• You have visible white, red, or mixed patches that have not improved in two or three weeks
• There is a lump, thickened area, or one-sided swelling inside your cheek
• Cheek biting started suddenly after dental work or trauma and has not settled
• You feel ashamed, anxious, or depressed about the habit and it is affecting your social life^[9,21,26,30]

A dentist or oral medicine specialist can usually diagnose frictional lesions just by examining your mouth. Biopsy is sometimes used if the lesion looks atypical, persists despite removing trauma, or if there is concern about leukoplakia or early cancer.^[4,16,25]

• Constantly biting the inside of your cheek is common but not normal. It is often a mix of habit, stress, and bite mechanics.
• Chronic cheek biting causes frictional keratosis – a thickened, often white patch that is usually benign and not precancerous by itself.
• You should worry – and get checked – if sores, patches, or lumps do not heal within a couple of weeks, change rapidly, or are associated with pain, difficulty chewing, or swelling.
• Most people can dramatically reduce cheek biting with a combination of dental care, habit-breaking strategies, stress management, and, when needed, psychological support.

If you are stuck in a cycle of biting, soreness, and worry, you do not have to just “live with it.” A timely evaluation and a few targeted changes can protect both your mouth and your peace of mind.

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