Suddenly everything you eat is bitter in your mouth is usually caused by abnormal taste sensation, which may be caused by local oral irritants, oral mucosal diseases, and damage to the peripheral nervous system, as follows. 1. Oral local irritants: poor restorations in the oral cavity may lead to traumatic ulcers and microbial infections, which can cause abnormal taste, as well as chemical exposure factors, such as tobacco, toothpaste and so on, can also cause taste abnormalities. 2. Oral mucosal diseases: such as lichen planus and herpetic diseases can damage peripheral nerve endings and taste buds, while secreting purulent substances, resulting in abnormal taste. 3. Damage to the peripheral nervous system: trauma or surgical injury to the lingual pharyngeal nerve, tympanic cord, the lingual branch of the mandibular nerve may cause taste abnormalities. There may be other reasons why your mouth is suddenly bitter when you eat anything, so it is recommended that you go to the hospital in time for early targeted treatment.