Anaphylaxis
Anaphylaxis is a sudden, severe allergic reaction that can affect breathing and blood pressure. It is a medical emergency.
About anaphylaxis
Anaphylaxis is a sudden, severe allergic reaction that can affect breathing and blood pressure. It is a medical emergency.
What can cause it?
Common triggers include foods, medicines, insect stings, and latex; sometimes no trigger is found.
Anaphylaxis can cause airway swelling, breathing difficulty, low blood pressure, and symptoms in several body systems within minutes.
What a patient may notice
Symptoms vary from person to person. Possible signs may include:
- Trouble breathing, wheezing, or throat tightness
- Swelling of the lips, tongue, face, or throat
- Hives with dizziness, vomiting, or fainting
How clinicians find the cause
Anaphylaxis is diagnosed from the sudden symptom pattern and exposure history; treatment should not wait for blood tests. After recovery, an allergist may use skin or blood tests to identify the trigger.
Treatment and next steps
- 1
Give prescribed intramuscular epinephrine immediately and call 911.
- 2
A second dose may be included in the patient's emergency plan if symptoms persist and emergency help has not arrived.
- 3
Emergency monitoring and additional treatment are needed because symptoms can recur.
Supporting recovery
- Lay the person flat with legs raised when possible unless breathing is easier sitting up or vomiting requires a side position.
- Do not allow the person to stand or walk suddenly.
- Antihistamines and inhalers do not replace epinephrine.
What to expect
Symptoms often improve with immediate epinephrine and emergency treatment, but anaphylaxis can become fatal when treatment is delayed. Symptoms may return after appearing to resolve, so emergency evaluation and observation are required even when the person feels better. Future exposure can cause another severe reaction.
Possible complications
- Blocked airway or respiratory arrest
- Dangerously low blood pressure, shock, cardiac arrest, or injury from fainting
- A second phase of symptoms after the initial reaction improves
When to Contact a Medical Professional
This condition can be life-threatening. Call 911 or go to the nearest emergency department. Do not delay care to visit urgent care.
Use prescribed epinephrine immediately if available, then call 911. Do not wait for symptoms to improve.Get emergency help for severe trouble breathing, new chest pressure, fainting, seizure, sudden weakness on one side, uncontrolled bleeding, blue or gray lips, or a person who is difficult to wake.
Ways to lower risk
- Avoid the confirmed trigger and carry two epinephrine devices when prescribed.
- Check expiration dates and teach family, coworkers, or school staff how to help.
- Wear medical identification and keep a written emergency plan.
Trusted health information
This CHS patient-education page uses original wording and links to MedlinePlus for additional information.