EMT-Basic Exam: The Basics of Medical Emergencies - Allergic Reactions

An allergic reaction is an exaggerated immune response to a substance. Substances that can cause allergic reactions are called allergens. Food, medications, plants, and insect stings and bites are some of the many allergens. Those who come into contact with allergens and suffer an allergic reaction have symptoms ranging from itchy eyes to life-threatening conditions.

1. Causes of Allergic Reactions
Many substances can cause an allergic reaction, but the most common are food, medications, plants, and insect stings and bites. The following lists some of the common allergic reactions that EMT-Basics should look out for in the field:
- Food-based allergic reactions associated with crustaceans and peanuts
- Medical allergies to drugs such as penicillin and sulfa compounds
- Allergic skin reactions caused by some plants, such as poison ivy, or certain materials, such as latex
- Allergic reactions caused by insect bites or stings



Common food allergens include (clockwise from top left) nuts, shellfish, milk, eggs, and wheat.

2. Signs and Symptoms of Allergic Reactions
Mild allergic reactions present with simple symptoms such as swelling, pain, headache, itchiness, watery eyes, and a runny nose.
Severe allergic reactions, or anaphylaxis, may produce life-threatening symptoms. A patient experiencing anaphylaxis may complain of a warm, tingling feeling or numbness in the extremities, mouth, face, and chest. The patient’s skin may become flushed and hives may appear. The patient’s face and neck may swell, which may lead to respiratory difficulty, so maintaining an open airway is vital.
Severe allergic reactions can also affect the heart. When hypoperfusion occurs, the heart rate increases in an attempt to maintain proper blood pressure. When the patient’s blood pressure decreases, the patient may suffer an altered mental status. This is often a key sign of a severe allergic reaction.

3. Emergency Care for Allergic Reactions
When you assess a patient experiencing an allergic reaction, determine the cause of the reaction and the patient’s history of allergies and note your general impression of the patient’s condition.
If the patient is having an allergic reaction that includes respiratory distress and has a prescribed epinephrine autoinjector, you may administer this medication with permission from the medical direction physician. Also remember to monitor the patient’s airway at all times.

Related Topics You Should Review:
- Epinephrine autoinjectors
- Respiratory distress