Oral Thrush (Candidiasis): This is the most common cause of white patches on the tongue, especially in immunocompromised individuals, those with poor oral hygiene, or users of inhaled corticosteroids. The patches can be wiped off, but they may bleed underneath.

Leukoplakia: A condition where thick, white patches or lesions develop on the tongue, often associated with chronic irritation or tobacco use. It can be a precursor to oral cancer, so it's crucial to monitor these lesions.
Oral Lichen Planus: An autoimmune condition that can cause white, lacy patches on the tongue and other mucous membranes. It's often associated with other symptoms like redness and discomfort.
Trauma or Irritation: White patches can appear due to mechanical irritation from sharp teeth, dental appliances, or accidental biting of the tongue.

Oral Cancer: Although less common, white patches on the tongue can be an early sign of oral cancer, particularly if they are persistent, grow in size, or are accompanied by other symptoms like difficulty swallowing or a lump in the neck.
Syphilis (Secondary): In rare cases, secondary syphilis can cause white patches on the tongue, along with other systemic symptoms. Missing this diagnosis can have significant health implications if left untreated.

Pemphigus Vulgaris: A rare autoimmune disease that can cause blistering of the skin and mucous membranes, including the tongue, sometimes presenting with white patches.
Lichenoid Drug Reaction: Certain medications can cause lichenoid reactions, which might include white patches on the tongue, similar to oral lichen planus.
White Sponge Nevus: A rare genetic condition that affects the mucous membranes, causing white, thickened patches on the tongue and sometimes other areas. It's usually benign but can be a part of a syndrome with other systemic manifestations.