A drop (cold) or rise (heat) of temperature of the skin can cause hives in susceptible individuals. The source of the heat can be external or internal body heat. Since physical exertion can raise the core body temperature, exercise sometimes causes hives, known as cholinergic urticaria . The ability of (cold) temperature to cause histamine release can also be demonstrated by touching a patient’s skin with an ice cube (producing cold urticaria – see figure 1). Fatal, sudden fall of core temperature has been observed in patients with cold urticaria, diving into a cold stream or pool.
To ensure there is no active (hidden) infection causing the hives, some doctors have prescribed a course of antibiotics . In most cases, these did not resolve the cholinergic urticaria symptoms. However, in at least one case reported, an individual reported symptoms resolving after a course of antibiotics. However, more research would need to be conducted to rule out coincidental remission, which happens very frequently with cholinergic urticaria. This condition often spontaneously disappears, which can lead one to believe it was the result of the treatment (which may not be the case).