
They are white lesions inside the cheeks, but also affect the lips, gums and tongue. It can affect other parts of body like skin and genital area. The word lichen refers to the lichen plant which grows on rocks or trees, while the word planus in Latin means “flat”.
The streaks are not usually painful or itchy. There may be redness and blistering of the gums. Painful ulcers can develop which is called erosive lichen planus. The patient’s sense of taste may become affected. Some experience a metallic taste and dryness of mouth. Spicy foods, crispy foods, and tomato products can exacerbate symptoms.
Oral lichen planus is more common in women than in men. The first attack may continue for weeks, and even months, while recurrences can go on for years – recurrences are more common in cases of oral lichen planus.
The exact cause of lichen planus is unknown. However, it is likely to be related to an allergic or immune reaction. Sometimes lichen planus may occur as a reaction to some medicines, such as beta-blockers, anti-inflammatory medications, phenothiazines (a group of tranquilizing drugs with antipsychotic actions) etc.
Diagnoses oral lichen planus by taking a punch biopsy.

Any Treatment?
Lichen planus is not a curable condition. However, when it affects the skin it usually clears within several months or sometimes this may take years. Treatment focuses on easing symptoms until the rash clears.
Treatments may include:
and Antihistamines
and Lidocaine mouthwashes
and Topical corticosteroids or oral corticosteroids such as prednisone to reduce swelling and suppress immune responses. Corticosteroids may be injected right into a lesion.
and Laser Treatment: white lesions if they persist can be removed by laser as shown in the video
Complications
Mouth ulcers that are there for a long time may develop into oral cancer but rare.