You suspect a gustatory hallucination in a patient. Before revealing the answer, decide how you would assess for this.

Ask specifically whether a taste is present with nothing in the mouth, food, drink, or substance to account for it, and characterise its quality, since metallic or bitter unpleasant tastes are most commonly described. Ask separately about smell, given how closely the two senses interact and how frequently they occur together, without assuming the two symptoms are the same experience. Ask carefully, and without leading, whether the patient has linked the taste to a belief about being poisoned, since this would represent a separate, delusional elaboration layered on top of the perceptual experience rather than the hallucination itself.