Hello, Thanks for writing to us. Hives, also known by their medical name of Urticaria, are raised, flat-topped bumps that are smooth to the touch and typically red in colour. Some hives are caused by allergies to such things as foods, medications, and insect stings, but in the majority of cases, no specific cause for them is ever found. Rarely, angioedema of the throat, tongue, or lungs can block the airways, causing difficulty breathing. Testing will depend on your medical history and a thorough exam by your primary care doctor or dermatologist. I do hope that you have found something helpful and I will be glad to answer any further query.