This article is a case report of a female patient in whom sour and spicy foods evoked trigeminal neuralgia (TN). An attempt to reveal the underlying pain mechanism is described and discussed. The 81-year-old woman had been suffering from classical TN since the age of 50. Attacks occurred spontaneously or in response to mechanical stimuli. In addition, sour and spicy foods also evoked TN attacks and were therefore avoided for years. Medical treatment was initially effective, but two radiofrequency ablations of the gasserian ganglion were required later on and yielded good, albeit incomplete, pain relief. Sensory examination consisted of application of a mechanical stimulus and sweet, salty, sour, and spicy solutions to the anterior part of the tongue and the mandibular mucosa on both sides. Mechanical stimuli were felt but produced no pain. When applied to the tongue, the tastes of all solutions were identified but produced no pain. When applied to the mucogingival line, none of the solutions was identified but the sour and the spicy solutions provoked TN immediately following their application. These findings suggest that in this patient, sour and spicy solutions may have evoked TN attacks by direct activation of trigeminal C-nociceptors, possibly via interactions with transient receptor potential vanilloid 1 receptors.