Responses (1) Itching skin from caffeine sensitivity is most likely caused by an allergic reaction in the body. There's a difference between being sensitive to caffeinated beverages and foods and having an allergy. Itching skin is a sign of an allergic reaction caused by increased histamine levels in the skin. If you notice that your skin becomes inflamed, itchy and irritated after consuming caffeine, make an appointment with an allergist for testing and a clinical diagnosis.