Anaphylaxis is a severe, sometimes life-threatening, allergic reaction. The reaction includes facial swelling, low blood pressure, and breathing difficulties.



The symptoms of anaphylaxis usually occur within minutes after exposure to an allergen, but can occur hours later. Symptoms may include hives and itching; swelling, redness, stinging or burning, especially on the face, mouth, eyes, or hands; lightheadedness, caused by a drop in blood pressure; obstruction of the nose, mouth, and throat ; severe respiratory distress; chest tightness, shortness of breath, wheezing; nausea, vomiting, cramping, diarrhea, heart arrhythmias; convulsion and shock.


Substances that cause anaphylaxis are often called allergens or triggers. Common triggers include medications, including antibiotics, seizure medications, and muscle relaxants; insect stings or bites; vaccines; injected dyes used in some types of x-rays; foods and food additives, especially eggs, peanuts, seafood, cow's milk, soy, and sulfites; blood products and latex products (gloves, condoms, etc.)


Diagnosis of anaphylaxis is based on the symptoms. Anaphylaxis will be suspected if there are symptoms and the patient has been exposed to a likely allergen.


Anaphylaxis is a medical emergency that requires immediate medical treatment, including epinephrine (Adrenaline) injection to make blood vessels contract, relax the airway, stops itching and hives, and relieves gastrointestinal cramping. Other medications such as cortisone drugs, or antihistamines may be given after the epinephrine to help prevent the return of acute symptoms. Cardiac measures such as oxygen, intravenous (IV) fluids, and cardiac monitoring will ensure that the heart, lungs, and blood pressure remain stable. Severe anaphylaxis may require mechanical ventilation, until swelling is brought under control.


Avoiding substances that trigger anaphylaxis is the best prevention. In addition allergy shots can decrease the risk of anaphylaxis and reduce the severity of the reactions.

It is important to inform health professionals about history of allergies before taking any medication. When possible, it is also important to ask that medications be taken as pills since allergic reactions can be more severe with injected medications. It is advised to always remain in the health professional's office 15 minutes after receiving an injection.


Complications of anaphylaxis can vary low blood pressure, syncope, shock, heart failure , and death.


Risk factor include previous mild allergic reaction to the substances listed above; history of eczema, hay fever, or asthma; and children who have spina bifida and urogenital defects.


Most people will take 2 or 3 days to recover from anaphylactic shock and feel quite unwell and drained for up to a week.