Food and other particles are picked up by your taste buds that communicate a message to your brain through nerves. You’re born with over 10,000 taste buds that can pick up on five different sensations: sweet, sour, bitter, salty, and umami. Persistent unpleasant taste in your mouth can affect anyone and presents as a “foul, salty, rancid, or metallic taste sensation.”
You can experience a bad flavor from the dysfunction of any of the parts involved with tasting: the taste buds themselves, the nerves that carry the message, and your brain itself. It can also be caused by medications, vitamins, or other culprits that release bad-tasting chemicals into your saliva or mouth.
Helpful tip: If any of these sound scary to you, rest assured that the cause of your unpleasant taste is usually benign (harmless) unless it presents alongside other symptoms, according to the Cleveland Clinic.