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When should I go to the emergency room (ER) for an allergic reaction?

If you have an allergic reaction, call 911 or go to the hospital emergency room for:

  • Swelling of the face or throat
  • Trouble swallowing
  • Trouble breathing
  • Being dizzy or passing out
  • Coughing and vomiting

These are signs of a dangerous allergic reaction. Get medical help right away!

Call or go to the doctor or clinic if:

  • Your whole body has reacted strongly to a bite or sting (bee, wasp, hornet, fire ant, and so on)
  • Your body has had a bad reaction to food or medicine

Allergic reactions vary by severity and how they look. You may have a rash only in a small area, which gets better with over-the-counter (OTC) medication. You may not need an emergency room (ER) visit.

Another allergic reaction—called anaphylactic reaction—may be life threatening and requires prompt treatment. Go to the ER immediately if you have:

  • shortness of breath
  • swelling to lips or tongue
  • a feeling that your throat is closing 

You should also go to the ER if you have an unknown rash and severe itching and have tried OTC medication without relief. Allergic reactions may start mild and get worse. It’s always important to monitor your symptoms. If you have any concerns, doctors are always available to treat you in the emergency room.

Allergic reactions should be taken seriously. We recommend being seen by a doctor for any allergic reactions that concern you. Symptoms that should prompt an immediate emergency room visit include any difficulty breathing, swelling of the throat or mouth, difficulty swallowing and lightheadedness. Other significant reactions include rash, diarrhea, abdominal pain and itching.

Any severe allergic reaction that compromises breathing or the heart should be immediately transported to the emergency room. If the patient has injectable epinephrine at home and knows how to use this, that should be injected. The patient then should be taken to the emergency room. Other reactions such as severe hives, swelling, gastrointestinal problems that do not respond to medications should also should be transported to the emergency room.

If you have an allergic reaction you should go to the emergency room (ER) for red flag symptoms that may indicate anaphylaxis, which essentially prevents you from being able to breathe. You should get to the ER as soon as you can. These symptoms include:

  • wheezing
  • shortness of breath
  • throat feels like it's swelling
  • abdominal pain
  • nausea
  • diffuse rash

If you just have a simple rash, it'll probably respond really well to diphenhydramine. You could try that before coming to the ER. But if you're worried at all about an allergic reaction, it's better to be safe than sorry. Go to the ER.

Dr. Alan Young, MD
Family Practitioner

You should go to the emergency room (ER) for an allergic reaction if you have been exposed to something you know you have a severe allergy to, facial, lip or tongue swelling or trouble breathing. Allergic reactions often cause hives, but that's not a reason to go to the ER.

Trinity Health is a Catholic health care organization that acts in accordance with the Catholic tradition and does not condone or support all practices covered in this site. In case of emergency call 911. This site is educational and not a substitute for professional medical advice, always seek the advice of a qualified health care provider.

You should go to the emergency room (ER) for an allergic reaction right away if any of the following symptoms are present:

  • a rash, such as hives
  • nausea and vomiting
  • swelling of the eyes
  • swelling of the mouth and the throat, which can eventually cause your airway to close off

Allergic reactions can come on rapidly and without much warning. They can also be life-threatening, whether it's caused by a bee sting, an ant bite, a peanut or even a strawberry. Various things can cause allergic reactions that can be quite serious.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.