Dysgeusia is commonly used to refer to any type of distortion or reduced ability to taste. If the cause of the condition is unknown, it is called idiopathic dysgeusia.

Specific taste disorders include:

• Hypogeusia. Reduced ability to taste. This may be a temporary condition or it may persist. This is a common type of taste disorder.
  
  
• Ageusia. Inability to detect taste. This may apply to just one of the basic taste sensations (e.g., total loss of ability to taste anything bitter), or it may involve all (e.g., anything consumed has no detectable taste). Most often, this is a temporary condition that resolves once its cause (e.g., upper respiratory infection) goes away or is treated. True (permanent) ageusia is rare and involves unidentified or untreatable causes (e.g., nerve damage) .
  
  
• Parageusia. A persistent bad taste in the mouth or altered sense of taste. The taste is commonly described as metallic, salty, foul or rotten. This can be a debilitating type of taste disorder. It is usually a temporary condition that can have many different causes, including poor dental hygiene and many dental conditions (e.g., abscess, periodontal disease). Alternatively, the taste of foods may change. For example, a formerly pleasant-tasting food may become unpleasant. Parageusia  most often appears later in life. This term is sometimes used interchangeably with dysgeusia.