Fever from caffeine.

Since childhood, a 53-year-old women had developed chills, high-grade fever, myalgia, and cephalea after the ingestion of coffee, tea, cola beverages, and some oral "antiflu" compounds. Skin prick tests performed with all the implicated substances were negative. Single-blind oral challenges with both caffeine and theophylline were positive, reproducing exactly the same clinical symptoms and fever. Oral challenge with pentoxifylline was negative. We report a case of caffeine-induced fever in which we have demonstrated cross-reactivity with theophylline, but not with pentoxifylline.