Background: Combined ingestion of caffeine and nicotine may elicit complex neurovascular and psychosomatic responses in susceptible individuals.Methods: A single-subject, self-monitored challenge involving 382 mg caffeine and 9 mg nicotine was performed, with real-time physiological and symptom tracking.Results: The subject developed vasomotor instability, anxiety, sensory hypersensitivity, and a delayed migraine-like state. Re-exposure to nicotine intensified symptoms.Conclusion: These findings suggest a reproducible post-stimulant phenomenon involving dopaminergic-cholinergic dysregulation and inflammatory activation, which may be relevant to psychopharmacology and stress-induced sensitization syndromes.