The symptoms of lichen planus are a bit similar to the effects of overexposure to materials used in color photography such as developers, gold, bismuth, and arsenic. When lichen planus infects the mouth, it is often mistaken for allergic reactions to certain candy, chewing gums, dental hygiene products, filling material, or medications. The symptoms of lichen planus have the tendency to appear instantly, though in some cases, they may surface gradually, especially if the lesions appear on the patient’s arms or legs. Once the lesions become apparent, the patient may experience burning sensations, dryness, and a "metallic" taste in the mouth.

The lesions will gradually become flat and glistening, and then they will become purplish with white spots or lines. The patient may experience mild to severe itching sensations. Alternately, if the lesion is whitish and lacy, it might be not as itchy and painful as a purple lesion. However, if the lesion becomes eroded, one must expect that it will be painful and will often cause a burning sensation. If the lesions occurred in the mouth of the patient, they may undergo six different forms. Typically, the lesions in the mouth may appear as eroded ulcers, white plaques, or lacy white streaks. Also, the gums will be affected by these lesions. Lesions may make the patient’s gums peel off, thus exposing raw and red gums.