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Signs and Symptoms of Allergy Attacks

An allergy is a reaction to a usually harmless substance, such as pollen or peanuts. The body mistakenly identifies the trigger as an invader and produces antibodies to fight the substance, causing symptoms that range from uncomfortable to life-threatening. The Mayo Clinic says the most common triggers include inhaled allergens, food, insects and medication.

  1. Respiratory Symptoms

    • When histamine is released in response to a suspected intruder, it affects several of the body's systems. One of the most common effects is on the respiratory system. According to Pharmacorama.com, histamine causes smooth muscles to contract. When smooth muscles surrounding the airway contract, they constrict airflow to the throat, trachea and lungs, causing difficulty breathing, wheezing and shortness of breath. When capillaries become more permeable, fluid leaks out, causing the nose to run. Other respiratory symptoms can include nasal congestion, sneezing and coughing.

    Digestive Symptoms

    • Histamine receptors cause the stomach to produce more acid, often resulting in digestive complaints. The University of Maryland Medical Center states that some common symptoms of food allergies include nausea, vomiting, diarrhea and stomach cramps. The National Institutes of Health note that nausea is a common allergic reaction as well as vomiting. Diarrhea, with loose, watery stools more than three times in a day, is another symptom and is often accompanied by cramping of the intestines.

    Skin-related Symptoms

    • Itching is a primary symptom in an allergic reaction. The Mayo Clinic lists itching as a symptom in almost every allergy. Sites of itching can include the eyes, nose, throat and, most commonly, skin. Because of histamine's effect on the permeability of capillaries, blood fluid leaks into the space between cells around blood vessels in the skin, according to the American Academy of Dermatology. This causes itchy, swollen areas called hives (urticaria). Hives are a common symptom in food, drug and insect allergies. Swelling, also caused by the release of histamine, can occur near the eyes as well as in the nasal passages, tongue or a localized site.

    Other Symptoms

    • The American Academy of Allergy, Asthma and Immunology says that anaphylaxis is a severe allergic reaction that can quickly lead to an emergency medical situation. Symptoms appear within 30 minutes of exposure to the allergen and include a red, itchy rash with hives, swelling of the airways or other parts of the body, chest tightness, wheezing, dizziness, loss of consciousness and a hoarse voice. If these symptoms occur, call 911 immediately.

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