Causes
Anaphylaxis can occur in response to almost any foreign substance. Common triggers include venom from insect bites or stings, foods, and medication. Foods are the most common trigger in children and young adults while medications and insect bites and stings are more common in older adults. Less common causes include: physical factors, biological agents such as semen, latex, hormonal changes, food additives such as monosodium glutamate and food colors, and topical medications. Physical factors such as exercise (known as exercise-induced anaphylaxis) or temperature (either hot or cold) may also act as triggers through their direct effects on mast cells. Exercise induced events are frequently associated with the ingestion of certain foods. During anesthesia, neuromuscular blocking agents, antibiotics, and latex are the most common causes. The cause remains unknown in 32-50% of cases, referred to as "idiopathic anaphylaxis".
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