Even small traces of peanuts can cause deadly reactions in people with severe peanut allergies. Constriction of the airways, a drop in blood pressure, a racing heart and dizziness are signs of anaphylaxis, which requires an emergency injection of epinephrine.

Tree nuts like walnuts, pecans, cashews and pistachios can also cause anaphylaxis in people with allergies. Some people can tolerate certain nuts, but are sometimes advised to avoid all nuts just in case.

Wheat and its glue-like protein gluten can cause itchiness and swelling of the mouth, throat and skin, as well as gastrointestinal symptoms like nausea, cramping and diarrhea in people with allergies. Severe wheat allergies can trigger anaphylaxis. The best treatment is to avoid exposure, a tall order for such a common ingredient.

Weeds tend to release their pollen in late summer or early fall. Ragweed, a common culprit, can trigger allergic rhinitis, better known as hay fever, a miserable set of symptoms that includes runny nose, watery eyes and sore throat.

Milk allergies can cause wheezing, hives, vomiting, diarrhea and anaphylaxis, a life-threatening reaction. The only way to prevent milk allergy symptoms is to avoid milk, and replace it with another good source of calcium.

Soy allergies can cause hives and, in rare cases, life-threatening anaphylaxis. Most children grow out of soy allergies, but some have to avoid the bean for life.

Allergic reactions to shellfish like shrimp, crab, lobster and squid can range from hives and nasal congestion to anaphylaxis. Antihistamines can quell the more mild symptoms, but people with severe allergies should carry an epinephrine injector at all times.

Bony fish like cod, haddock, halibut, mackerel, trout and salmon can trigger rashes, hives, digestive symptoms and anaphylaxis in people with fish allergies. Some people can tolerate certain kinds of fish and not others.

Egg allergies can trigger hives, nasal inflammation, vomiting and, in severe cases, anaphylaxis. Some people can tolerate eggs when cooked into foods like cookies, but others have to avoid them altogether.

Most trees release their pollen in late winter or early spring, wreaking havoc on the sinuses of seasonal allergy sufferers. The worst offenders include ash, birch, cedar, elm, oak and willow trees.

Mold can grow outside in compost piles and rotting leaves, as well as inside in moist crevices, triggering a runny nose, itchy throat and eyes, and coughing in people with allergies. The best treatment is avoidance.

Pets can trigger allergic reactions through their dander, saliva or urine. People with pet allergies can opt for animals without fur or ones that don't shed dander. When visiting pet owners, antihistamines can help keep mild allergy symptoms at bay.

Allergic reactions to drugs can cause rashes and hives, wheezing and swelling and, in severe cases, anaphylaxis. Treatments range from antihistamines to emergency epinephrine. Penicillin is the most common drug allergen.

Latex can cause skin rashes and hives as well as asthma symptoms in people with allergies. In severe cases, the natural rubber can trigger anaphylaxis. Avoidance of the stretchy material, commonly used in medical supplies, is key.

Most grasses release their pollen in late spring or early summer. Pollen maps can help allergy sufferers prepare by for a day outside with antihistamines.

Dust can trigger a runny nose, itchy eyes and sneezing in people with allergies, not to mention asthma symptoms like wheezing and shortness of breath. Non-carpet flooring and HEPA air filters can help minimize exposure.

Bug bites and stings can trigger swelling, hives and difficulty breathing in people with allergies. They can also trigger a drop in blood pressure, dizziness and cardiac arrest. People with severe allergies should carry an epinephrine injector.