HomeAsk the allergist: Your questions answered – February 2020

Ask the allergist: Your questions answered – February 2020

February 7, 2020

Ask the allergist is a regular feature in our newsletters where Dr. Julia Upton answers your questions!

Dr. Julia Upton

Dr. Julia Upton is a Canadian allergist who is on staff at Toronto’s SickKids Hospital in the Immunology and Allergy Department. She is an Assistant Professor in the Department of Paediatrics at the University of Toronto and is the Section Chair of Food Allergy and Anaphylaxis with the CSACI. Dr. Upton is also a member of our Healthcare Advisory Board.

Please note: Dr. Upton is answering as an individual allergist and her answers do not constitute an official position of her affiliated organizations. Her responses are for informational purposes only and do not constitute specific medical advice, recommendations, diagnosis, or treatment. Please talk to your doctor about any concerns or questions you may have regarding your own health or the health of your child.

This month she answers your questions about epinephrine.

Once epinephrine is given, how quickly does it work?

Once an epinephrine auto-injector (e.g. EpiPen®) is injected into the mid-outer thigh, the medication starts working within a few minutes to open the airways and improve blood pressure. It is important to note the time of a first dose of epinephrine in case a second dose is needed. 

When should a second dose of epinephrine be given?

If there is no improvement in symptoms or symptoms are getting worse, a second dose of epinephrine can be given as early as 5 minutes after the first dose. The signs of a reaction worsening include more difficulty breathing or a decreased level of consciousness.

How long does a dose of epinephrine last, is it only 15 minutes?

The effects of intramuscular epinephrine are rapid and the highest amount (the peak) is delivered within 5-15 minutes and then it is cleared by your body over hours. Some people need two or more doses to control the allergic reaction. Or the allergic reaction may come back after the highest amount of epinephrine is gone. 

After you receive a dose of epinephrine, 9-1-1 or local emergency medical services should be called. You should then go to the hospital immediately (ideally by ambulance) for further treatment and/or evaluation. Medical advice is required to determine which further treatments and monitoring are needed. 

Anaphylaxis guidelines recommend that a second dose of epinephrine be given in 5 to 15 minutes after the first dose. This may be why some people think the dose lasts for 15 minutes.

Thank you, Dr. Upton, for your insightful and helpful answers!

Learn more about epinephrine on our treating reactions page and our topic sheet.

Do you have a question you’d like to ask Dr. Upton in the months to come? If so, please send it along to us at info@foodallergycanada.ca.

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