Anaphylactic shock--also called anaphylaxis--occurs when a patient develops a severe allergic reaction to a particular allergen, such a specific food or medicine. The signs and symptoms of this reaction typically develop within seconds or minutes after exposure to a particular allergen, warns the Mayo Clinic. Anaphylactic shock can be life-threatening and require immediate emergency medical intervention.
Swelling, Hives and Itching
The most common signs and symptoms of anaphylactic shock are hives and itching. Exposure to an allergen elicits a sudden, severe inflammatory response by the immune system. As a result, patients can exhibit significant swelling of the face, throat, tongue, lips or extremities, explain health officials with the British Broadcasting Corporation (BBC), a leading global news information company. Certain patients can also develop hives across the skin. The affected skin can appear red or irritated, and may be warm to the touch. Severe itching can also occur, causing the patient to scratch at the affected skin.
Low Blood Pressure and Dizziness
Anaphylactic shock can cause a sudden drop in the blood pressure, reports the BBC. When this occurs, a patient can appear confused, anxious, nervous or unstable due to sensations of severe lightheadedness or dizziness, explains Medline Plus, a health information website established by the National Institutes of Health. Patients may also have an abnormally weak, fast pulse due to an increased heart rate. These symptoms may occur in conjunction with slurred speech or loss of consciousness.
Airway Constriction and Difficulty Breathing
This type of allergic reaction can cause airway constriction in certain patients. When the airway passages narrow, patients can experience difficulty breathing. Wheezing--a high-pitched squeaking noise caused by air passing through tight airway spaces--can also occur, explain doctors at the Mayo Clinic. Some patients may begin to cough or gasp for air. Nasal congestion may also occur, which can contribute to breathing difficulties. If immediate treatment is not received, some patients may stop breathing due to anaphylactic shock.
Vomiting and Nausea
Patients who experience anaphylactic shock following ingestion of an allergen can develop stomach upset symptoms, warn Mayo Clinic doctors. These symptoms can include nausea, vomiting or diarrhea, which may occur in conjunction with abdominal cramping or bloating. Stomach upset symptoms can be uncomfortable and often develop within several minutes following exposure to an allergen.
