<unk>  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<unk>  or temperature (either hot or cold) may also act as triggers through their direct effects on mast cells. Events caused by exercise are frequently associated with cofactors such as the ingestion of certain foods or taking an NSAID. 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<unk> ." Six vaccines (MMR, varicella, influenza, hepatitis B, tetanus, meningococcal) are recognized as a cause for<unk> , and HPV may cause<unk>  as well. Food Many foods can trigger<unk> ; this may occur upon the first known ingestion. Common triggering foods vary around the world due to cultural cuisine. In Western cultures, ingestion of or exposure to peanuts, wheat, nuts, certain types of seafood like shellfish, milk, fruit and eggs are the most prevalent causes. Sesame is common in the Middle East, while rice and chickpeas are frequently encountered as sources of<unk>  in Asia. Severe cases are usually caused by ingesting the allergen, but some people experience a severe reaction upon contact. Children can outgrow their allergies. By age 16, 80% of children with<unk>  to milk or eggs and 20% who experience isolated<unk>  to peanuts can tolerate these foods. Medication Any medication may potentially trigger<unk> . The most common are β-lactam antibiotics (such as penicillin) followed by aspirin and NSAIDs. Other antibiotics are implicated less frequently. Anaphylactic reactions to NSAIDs are either agent specific or occur among those that are structurally similar meaning that those who are allergic to one NSAID can typically tolerate a different one or different group of NSAIDs. Other relatively common causes include chemotherapy, vaccines, protamine and herbal preparations. Some medications (vancomycin, morphine, x-ray contrast among others) cause<unk>  by directly triggering mast cell degranulation. The frequency of a reaction to an agent partly depends on the frequency of its use and partly on its intrinsic properties.<unk>  to penicillin or cephalosporins occurs only after it binds to proteins inside the body with some agents binding more easily than others.<unk>  to penicillin occurs once in every 2,000 to 10,000 courses of treatment, with death occurring in fewer than one in every 50,000 courses of treatment.<unk>  to aspirin and NSAIDs occurs in about one in every 50,000 persons. If someone has a reaction to penicillin, his or her risk of a reaction to cephalosporins is greater but still less than one in 1,000. The old radiocontrast agents caused reactions in 1% of cases, while the newer lower osmolar agents cause reactions in 0.04% of cases. Venom Venom from stinging or biting insects such as Hymenoptera (ants, bees, and wasps) or Triatominae (kissing bugs) may cause<unk>  in susceptible people. Previous reactions that are anything more than a local reaction around the site of the sting, are a risk factor for future<unk> ; however, half of fatalities have had no previous systemic reaction. Risk factors People with atopic diseases such as asthma, eczema, or allergic rhinitis are at high risk of<unk>  from food, latex, and radiocontrast agents but not from injectable medications or stings. One study in children found that 60% had a history of previous atopic diseases, and of children who die from<unk> , more than 90% have asthma. Those with mastocytosis or of a higher socioeconomic status are at increased risk.
Anaphylaxis
Asthma
Heat urticaria
Allergy
Cholinergic urticaria
Carcinoid syndrome
Tachyphylaxis
Angioedema