Oral lichen planus is a chronic inflammatory condition affecting the tissue lining inside the mouth, causing white patches, redness, or painful sores that come and go over time. This condition cannot be spread from person to person and, while it has no cure, treatments can help manage symptoms and improve quality of life.

Understanding Oral Lichen Planus

Oral lichen planus affects the mucous membranes, which are the thin tissues that line the inside of the mouth. These membranes normally protect the cheeks, gums, tongue, and other parts of the mouth. With oral lichen planus, however, inflammation damages these tissues for reasons that doctors do not fully understand. The condition creates abnormal patches or lesions, which are areas of damaged or changed tissue, that can appear in different patterns and cause varying levels of discomfort.^[1]

The name “lichen planus” comes from two sources. The word “lichen” refers to a moss-like plant that grows on rocks with a web-like appearance, which resembles how the condition looks in the mouth. “Planus” is Latin for “flat,” describing the flat-topped nature of the lesions.^[4] This condition is not dangerous in itself, but it requires regular monitoring by healthcare professionals because it can cause discomfort and, in rare cases, may be associated with other health concerns.^[2]

Epidemiology

Oral lichen planus affects approximately 2 percent of the general population worldwide.^[3] The condition does not discriminate based on geography, but certain demographic patterns emerge when looking at who develops this disease. Women are significantly more likely to develop oral lichen planus than men, with females being 3 to 4 times more affected.^[2] This gender difference is consistent across different populations, though researchers do not yet understand why women are more vulnerable.

The disease can appear at any age, but it most commonly affects middle-aged and older adults. Most people who receive a diagnosis are between 30 and 70 years old, with women over the age of 50 being the most commonly affected group.^[3] The average age of onset is around 56 years.^[13] While oral lichen planus can occur in children and young adults, these cases are relatively uncommon. The condition appears to develop most frequently during the middle and later years of life, suggesting that age-related changes in the immune system or accumulated environmental exposures may play a role.

Causes

The exact cause of oral lichen planus remains incompletely understood by medical science. However, researchers have identified that the condition is related to how the immune system functions. Under normal circumstances, the immune system protects the body by releasing immune cells that attack harmful invaders like bacteria and viruses. In oral lichen planus, something goes wrong with this protective mechanism. The immune cells, particularly a type called T cells, which are white blood cells that help fight infections, become confused and attack the tissue lining inside the mouth instead of protecting it.^[2]

Evidence suggests that oral lichen planus is a T-cell–mediated autoimmune disease, meaning it involves the immune system mistakenly attacking the body’s own tissues. Specifically, CD8+ T cells, a specialized type of T cell, trigger the death of cells in the oral epithelium, which is the layer of cells that lines the mouth. These T cells recognize something on the surface of mouth cells as foreign, even though it is part of the body. After this recognition, the T cells activate and cause the mouth cells to die through a process called apoptosis, or programmed cell death.^[5]

The dense accumulation of immune cells beneath the surface layer of mouth tissue in oral lichen planus consists of T cells and macrophages, which are cells that normally clean up debris and help coordinate immune responses. There are also increased numbers of T cells within the epithelium itself, concentrated near the damaged cells at the base layer. These activated CD8+ T cells may release chemical messengers called cytokines that attract even more immune cells to the area, creating a cycle of inflammation and tissue damage.^[5]

Research has shown that lesions of oral lichen planus contain increased levels of tumor necrosis factor (TNF)-α, a powerful cytokine involved in inflammation. Both the cells lining the mouth and the T cells in the tissue beneath express TNF, and studies have found elevated levels of this substance in both the blood and saliva of people with oral lichen planus.^[5] These findings suggest that TNF plays an important role in causing and maintaining the inflammation seen in this condition.

Although the specific trigger that sets off this immune reaction is unknown, it may be a self-peptide or an altered version of a normal body protein. If this is the case, oral lichen planus would be classified as an autoimmune disorder where the body attacks its own proteins. However, because no specific triggering substance has been definitively identified, some experts are cautious about calling it fully autoimmune and prefer to describe it as a cell-mediated immune response.^[3]

Risk Factors

Several factors increase the likelihood of developing oral lichen planus. Being female is one of the strongest risk factors, as women develop the condition 3 to 4 times more often than men.^[2] Age also matters, with the disease most commonly appearing in people between 30 and 70 years old, suggesting that middle age and beyond represent periods of increased vulnerability.^[2]

Certain medications appear to be associated with oral lichen planus or can trigger reactions that look very similar to the disease. These medicines include antifungals used to treat fungal infections, antiparasitic drugs, antiseizure medications for epilepsy, beta-blockers for heart conditions, diuretics that help remove excess fluid, and nonsteroidal anti-inflammatory drugs (NSAIDs) used for pain and inflammation.^[2] When medications cause mouth changes that resemble lichen planus, the condition is called a lichenoid reaction rather than true oral lichen planus.^[3]

Some systemic diseases appear more frequently in people with oral lichen planus, though the exact relationship is not fully understood. Hepatitis B and hepatitis C, which are viral infections affecting the liver, show an association with oral lichen planus. A comprehensive analysis of multiple studies found that people with hepatitis C virus infection have a statistically significant increased likelihood of developing oral lichen planus.^[13] Human papillomavirus (HPV) and primary biliary cirrhosis, a chronic liver disease, have also been reported in connection with oral lichen planus, but more research is needed to understand these relationships.^[2]

Beyond medications and diseases, several environmental and physical factors can trigger symptom flare-ups in people who already have oral lichen planus. Allergic reactions to certain foods, toothpaste ingredients, dental floss components, or materials used in dental procedures can worsen symptoms. Dental problems such as a misaligned bite, having rough or jagged teeth that rub against mouth tissues, or sharp edges on dental work can also trigger flare-ups. Mouth injuries from accidentally biting the cheek or tongue, mouth infections, and emotional stress or anxiety are additional triggers that many patients learn to recognize over time.^[2]

Genetics may play some role, as genes and immunity appear to be involved in the disease process.^[3] However, oral lichen planus does not seem to run strongly in families, and it is not considered an inherited condition that parents pass directly to children.^[6] The involvement of genetic factors more likely relates to how an individual’s immune system is programmed to respond rather than a specific gene that causes the disease.

Symptoms

The symptoms of oral lichen planus vary considerably depending on which type a person has and where in the mouth the lesions appear. There are two main types of oral lichen planus, each with distinct characteristics and levels of discomfort. The reticular type is the most common form and appears as white patches or thread-like lesions that can look lacy or web-like. These white lines or patches are slightly raised and commonly appear on the inside of the cheeks, though they can also occur on the gums, tongue, and inner lips.^[1] These lacy white lines are sometimes called Wickham’s striae, named after the physician who first described them.^[3]

The reticular form usually does not cause pain or other discomfort. Many people with this type of oral lichen planus only discover they have the condition during a routine dental examination, as they experience no symptoms that would prompt them to seek medical attention. Some patients may notice a slight roughness when they run their tongue over the affected areas, but this mild texture change typically does not interfere with daily activities like eating or speaking.^[1]

The erosive type of oral lichen planus is more severe and troublesome. This form appears as bright red, swollen tissues or open sores in the mouth. The red appearance results from the loss of the top layer of the mucous membrane in the affected area.^[3] Unlike the reticular type, erosive oral lichen planus often causes significant discomfort. People with this form experience a burning sensation or pain, particularly when eating or drinking. The symptoms worsen with certain types of food and beverages, especially those that are hot, acidic, crunchy, salty, or spicy.^[2]

Additional symptoms of erosive oral lichen planus include bleeding and irritation during toothbrushing, sensitivity that makes maintaining oral hygiene difficult, and inflammation of the gums. In severe cases, ulcers, which are deeper open sores, can develop on the gums, tongue, or roof of the mouth. These ulcers may cause pain even when not eating or drinking.^[2] The chronic pain and sensitivity can become so severe that some people avoid eating, potentially leading to weight loss and nutritional problems.^[2]

Less common forms of oral lichen planus include the papular type, which appears as small raised bumps; the plaque-like type, which shows as a dense thickening of the mouth tissue similar to white patches but with more substance; and the bullous type, which involves blister formation.^[5] These variations can sometimes overlap, with a patient experiencing more than one pattern at the same time or transitioning between types over the course of the disease.

Symptoms typically come and go in cycles of flare-ups and remissions. During a flare-up, symptoms worsen or new lesions appear. During remission, symptoms decrease or disappear entirely, only to return later. This pattern of relapsing and remitting makes oral lichen planus a chronic condition requiring long-term management.^[4] Early symptoms may include dryness in the mouth and a metallic or burning taste.^[8]

People with oral lichen planus may also develop lichen planus on other parts of the body. Approximately 15% of patients develop skin lesions, which typically appear as violaceous (purple-colored) itchy bumps with overlying white lines, most commonly on the trunk, wrists, or ankles.^[4] Around 20% develop lesions on the genitals, which can affect the vulva in women or the penis in men, causing similar symptoms of redness, white patches, and discomfort.^[4]

Prevention

Because the exact cause of oral lichen planus is not known, there is no way to completely prevent the condition from developing in the first place.^[6] However, once someone has been diagnosed with oral lichen planus, several preventive strategies can help reduce the frequency and severity of symptom flare-ups and minimize the risk of complications.

Maintaining excellent oral hygiene is one of the most important preventive measures. Studies have reported significant improvement in patients who receive regular professional teeth cleaning to remove calculus deposits and reduce sharp edges, combined with conscientious home care.^[5] Brushing teeth twice daily and flossing once daily helps keep the mouth clean and reduces inflammation. Using a soft-bristled toothbrush and gentle technique prevents further irritation to sensitive tissues.^[10]

Avoiding triggers that cause symptom flare-ups plays a crucial role in prevention. Many people with oral lichen planus find it helpful to keep a diary or log of factors that seem to worsen their condition, such as certain spicy or citrus foods, flavoring agents like peppermint or cinnamon, and stressful events.^[22] Once triggers are identified, avoiding them can lead to fewer and less severe flare-ups. Some patients report fewer ulcerations and less sensitivity when they switch from tartar control toothpastes to milder formulations.^[5]

Addressing dental issues promptly helps prevent physical trauma that can trigger or worsen oral lichen planus. Any sharp teeth, broken dental restorations, or prostheses that might cause physical trauma to areas of redness or erosion should be treated with conventional dental measures. Having teeth professionally scaled to remove calculus deposits and reduce sharp edges also helps.^[16] For patients who have lesions adjacent to dental fillings and test positive for metal allergies through skin patch testing, removing or replacing the offending dental material may lead to healing of the lesion.^[16]

Managing stress through relaxation techniques, counseling, or other stress-reduction strategies may help prevent flare-ups, as stress and anxiety are known triggers for many patients.^[16] Regular follow-up appointments with a dentist or healthcare provider allow for early detection and treatment of any changes, which can prevent minor problems from becoming severe complications.^[1]

To reduce the overall risk of serious mouth diseases, whether or not someone has oral lichen planus, certain lifestyle measures are recommended. Not smoking and avoiding smokeless tobacco products protects oral tissues from damage and reduces cancer risk. Limiting alcohol consumption also helps protect mouth tissues. Eating plenty of fresh fruits and vegetables provides nutrients that support tissue health and immune function.^[6]

For patients undergoing treatment, it is important to be aware that some topical corticosteroid therapies may increase the risk of developing oral fungal infections. While these infections are rarely symptomatic and generally do not complicate the healing of erosions, antifungal medications may be prescribed when an infection is present.^[16] Being aware of this possibility and reporting any unusual changes to a healthcare provider allows for prompt treatment if needed.

Pathophysiology

Pathophysiology refers to the changes in normal bodily functions that occur when a disease is present. Understanding what goes wrong at the cellular and tissue level helps explain why oral lichen planus causes the symptoms it does. The fundamental problem in oral lichen planus involves an immune-mediated attack on the cells lining the mouth. This process begins when CD8+ T cells, a type of immune cell, mistakenly recognize normal mouth cells as foreign or dangerous.^[5]

These T cells interact with keratinocytes, which are the main type of cell in the epithelium or lining layer of the mouth. The T cells recognize an antigen, which is a protein or molecule that triggers an immune response, in association with MHC class I molecules on the surface of keratinocytes. MHC class I molecules normally display pieces of proteins from inside the cell so that the immune system can check for infections. In oral lichen planus, the T cells incorrectly identify these displayed proteins as threatening.^[5]

Once activated, the CD8+ T cells trigger the keratinocytes to undergo apoptosis, which is a form of programmed cell death where cells systematically dismantle themselves. This explains why the erosive form of oral lichen planus shows loss of the top layer of tissue—the cells have been killed by the immune attack. At the same time, the activated T cells and possibly the keratinocytes themselves release cytokines, which are chemical messenger molecules that coordinate immune responses. These cytokines attract additional immune cells to the area, creating a dense infiltrate of T cells and macrophages just beneath the epithelium.^[5]

The specific cytokines involved in oral lichen planus pathophysiology have been studied extensively. Tumor necrosis factor-alpha (TNF-α) appears to play a central role. This powerful inflammatory molecule is present at increased levels in oral lichen planus lesions. Both the keratinocytes at the site of damage and the T cells in the inflammatory infiltrate produce TNF-α. Furthermore, these cells express increased levels of TNF receptors, which are proteins on cell surfaces that respond to TNF signals.^[5]

Beyond the lesion site itself, systemic changes can be detected. Serum and saliva from patients with oral lichen planus contain elevated levels of TNF-α, indicating that the inflammatory process has effects throughout the body, not just locally in the mouth.^[5] Other inflammatory molecules are also elevated. Patients with the erosive form of oral lichen planus show increased concentrations of interleukin-6 (IL-6) and neopterin in their saliva and blood, suggesting these substances may be particularly involved in the more severe variant of the disease.^[5]

Some research suggests that other molecules such as osteopontin, CD44, and survivin may also be involved in how oral lichen planus develops and progresses.^[5] Additionally, researchers have found that microRNA 4484 (miR-4484), which is a small piece of genetic material that regulates gene expression, is significantly elevated in the saliva of patients with oral lichen planus, suggesting it might serve as a marker of disease activity.^[5]

The visible changes in oral lichen planus result from this complex immune process. The characteristic white lines of reticular oral lichen planus, known as Wickham’s striae, represent areas of thickened keratin layer (hyperkeratosis) and increased granular layer (hypergranulosis) in the epithelium. Beneath this thickened surface lies the lichenoid inflammatory infiltrate—a band-like accumulation of T cells and macrophages mixed with cells containing melanin pigment.^[14] In the erosive form, the epithelium breaks down, creating the red, raw appearance as the underlying blood-rich tissue becomes exposed.^[3]

The pathophysiology explains why oral lichen planus is chronic and prone to flare-ups. The immune system has developed a pattern of responding inappropriately to antigens in the mouth tissues. Even when inflammation subsides during remission, the underlying immune programming remains unchanged. When triggered by stress, certain foods, physical trauma, or other factors, the immune response activates again, causing symptoms to recur. This cycle continues because the fundamental cause—the immune system’s misrecognition of mouth tissue as foreign—persists over time.^[4]