Hives are often misdiagnosed because they can be caused by an underlying condition or medications. The underlying conditions that may cause hives include food or drug allergies, stress, heat/cold sensitivity, and sweating. As for medications in particular, the most common culprits are aspirin and antibiotics. Side effects of medications, exposure to toxins, chemicals, or other substances may also provoke development of hives. Consequently, they become possible underlying causes of hives but are often misdiagnosed or overlooked as a cause.
For a comprehensive list of medications that can cause hives, click here (http://cureresearch.com/intro/medic.htm)