If your field of study is inflammation or if you try to keep on top of drug safety issues such as drug hypersensitivity you might have come across this term.
Simply put, urticaria is another word for hives (not The Hives) or skin rash which is sometimes one of the symptoms of drug-hypersensitivity (ie. a drug induced allergic response) . This type of reaction is usually triggered by mast cells that are located in the connective tissue of skin, gut, and respiratory and gastrointestinal tract. Mast cells can be stimulated to release histamine and other immune enhancing agents by a number of mechanisms, either through antibody (IgE) binding or direct exposure to offending agents, although the former mechanism is what most people are familiar with. However some drugs elicit a mast cell response by direct stimulation and avoid the immune system altogether. There are a number of drugs which fall into this category including opiates, codeine, amphetamines, atropine, muscle relaxants, pentamidine….