Throat Swelling and Trouble Breathing After Allergy: Call 911 Now

This is an emergency — what do I do first?

1. Use epinephrine if an auto-injector is available. Inject it into the outer thigh — through clothing is fine. Epinephrine is the only medication that effectively reverses anaphylaxis 1Ref 1Lieberman P, Mink L, et al. (Joint Task Force on Practice Parameters, AAAAI/ACAAI) (2023).Anaphylaxis: A 2023 practice parameter update.Epinephrine as the only first-line treatment for anaphylaxis; delayed epinephrine as the most consistent factor in anaphylaxis deaths; antihistamines inadequate as sole treatment; beta-blocker risk; biphasic reaction requiring ER observation. 2. Call 911 immediately. Tell the dispatcher this may be anaphylaxis. Do not drive to the hospital. 3. Lay the person flat and elevate their legs to maintain blood pressure — unless lying flat makes breathing worse, in which case keep them sitting up slightly. 4. Stay on the line with the dispatcher and do not leave the person alone. 5. A second dose of epinephrine can be used after 5–15 minutes if symptoms do not improve and a second auto-injector is available.

Antihistamines like diphenhydramine (Benadryl) are not adequate to stop anaphylaxis. They act too slowly and should only be used as an add-on after epinephrine 1Ref 1Lieberman P, Mink L, et al. (Joint Task Force on Practice Parameters, AAAAI/ACAAI) (2023).Anaphylaxis: A 2023 practice parameter update.Epinephrine as the only first-line treatment for anaphylaxis; delayed epinephrine as the most consistent factor in anaphylaxis deaths; antihistamines inadequate as sole treatment; beta-blocker risk; biphasic reaction requiring ER observation2Ref 2Cardona V, Ansotegui IJ, Ebisawa M, El-Gamal Y, Fernandez Rivas M, Fineman S, et al. (2020).World allergy organization anaphylaxis guidance 2020.Anaphylaxis recognition criteria — multi-system involvement, timing after allergen exposure, common triggers including food, stings, and medications; epinephrine as first-line treatment.

What are the warning signs of anaphylaxis?

Anaphylaxis typically involves more than one body system appearing together — often within minutes to a couple of hours of exposure 2Ref 2Cardona V, Ansotegui IJ, Ebisawa M, El-Gamal Y, Fernandez Rivas M, Fineman S, et al. (2020).World allergy organization anaphylaxis guidance 2020.Anaphylaxis recognition criteria — multi-system involvement, timing after allergen exposure, common triggers including food, stings, and medications; epinephrine as first-line treatment:

• Throat tightness, hoarseness, or a sense that the airway is closing
• Swelling of the tongue, lips, throat, or face
• Severe difficulty breathing, wheezing, or stridor (a high-pitched sound when inhaling)
• Skin turning pale, blue, or gray
• Sudden drop in blood pressure — dizziness, fainting, or feeling like passing out
• Rapid or weak pulse
• Loss of consciousness
• Severe vomiting or diarrhea combined with any of the above

When the airway is involved, treat as anaphylaxis — do not wait for other symptoms to confirm it.

What triggers anaphylaxis?

Common triggers include foods (peanuts, tree nuts, shellfish, fish, milk, eggs), insect stings (bees, wasps, hornets), medications (penicillin, aspirin, NSAIDs), latex, and — less commonly — exercise 2Ref 2Cardona V, Ansotegui IJ, Ebisawa M, El-Gamal Y, Fernandez Rivas M, Fineman S, et al. (2020).World allergy organization anaphylaxis guidance 2020.Anaphylaxis recognition criteria — multi-system involvement, timing after allergen exposure, common triggers including food, stings, and medications; epinephrine as first-line treatment. Symptoms typically appear within minutes but can occasionally be delayed up to a couple of hours. Knowing your trigger is important for prevention and for informing emergency responders.

What makes anaphylaxis more dangerous?

• Delay in using epinephrine is the most consistent factor in anaphylaxis deaths. When in doubt, use it 1Ref 1Lieberman P, Mink L, et al. (Joint Task Force on Practice Parameters, AAAAI/ACAAI) (2023).Anaphylaxis: A 2023 practice parameter update.Epinephrine as the only first-line treatment for anaphylaxis; delayed epinephrine as the most consistent factor in anaphylaxis deaths; antihistamines inadequate as sole treatment; beta-blocker risk; biphasic reaction requiring ER observation.
• Asthma significantly worsens the respiratory component of anaphylaxis and requires especially prompt treatment.
• Beta-blocker medications (used for blood pressure and heart conditions) can blunt the response to epinephrine and make anaphylaxis harder to treat. Tell emergency responders if you take a beta-blocker.
• A prior anaphylactic episode is the strongest predictor of future severe reactions. Anyone with a prior episode should carry a standing epinephrine prescription and have a written action plan.

What happens after the emergency — how do I prevent it happening again?

After a severe allergic reaction, follow-up with an allergist is important 3Ref 3American College of Allergy, Asthma and Immunology (2024).Anaphylaxis — Symptoms, Diagnosis, Treatment & Management.Post-anaphylaxis follow-up with an allergist: standing epinephrine prescription, allergen testing, written action plan, and immunotherapy assessment. Skin prick or blood tests can identify the specific trigger. The allergist can prescribe a standing epinephrine auto-injector, create a written anaphylaxis action plan, and assess whether allergy immunotherapy is an option for your trigger. Consistent access to epinephrine and avoidance of the known trigger are the two most effective safeguards.