I had been taking Tetracycline on and off for many years as an acne treatment. Very recently after taking a single dose I had what seemed like an an allergic reaction. Side effects included hives, high blood pressure, skin irritation. I found this very odd and I recalled the container of pills had gotten wet inside. Is it possible that exposure to water made the pills toxic or is it more likely that after years of taking Tetracycline I developed a severe allergy to it?