How long does anaphylaxis last?

how long does anaphylaxis last

You’re allergic to peanuts and you’ve just bitten into a chocolate that contains traces of peanuts. Your whole body breaks out in hives, your face and throat are swelling and tightening. You feel sick and dizzy and your breathing is wheezing and difficult. You’re experiencing an anaphylactic reaction. You take out your EpiPen and administer the adrenaline. What happens next? How long does anaphylaxis last?

Most people with Anaphylaxis know how to recognise the symptoms and how to give adrenaline but what happens next? How long does it take before the adrenaline starts to work? Should your symptoms disappear straight away? Should you call for an ambulance or use your second EpiPen?

How long does it take symptoms to go away after taking adrenaline?

Typically, serious symptoms of an anaphylactic reaction such as wheezing, difficulty in breathing and throat tightness improve within minutes of a dose of adrenaline. If serious symptoms aren’t improving or recur you may need that second dose but this is less common.

Other symptoms such as rashes and abdominal pain can take longer to go away. They usually improve over the course of an hour or so. Swelling, such as swollen eyelids or lips can take even longer before it’s gone down completely.

Adrenaline Pen Cases

How long does it take for adrenaline to wear off?

The effects of adrenaline may wear off after 10 – 20 minutes. By this time, the worst of your symptoms should have passed. If not, make sure you use your second adrenaline pen.

Should you call for an ambulance?

It’s always recommended that you call for an ambulance as soon as possible. You should call directly after you have administered your adrenaline. A biphasic reaction is when the symptoms go away at first, but hours later they come back. Sometimes they are more severe than the initial symptoms. This is why it’s important to go to the hospital and stay under observation for at least 4 hours.

Most people feel a lot better after a few hours or by the next day after an anaphylactic reaction. If you don’t, make sure you get checked out by your doctor. You could also check in with your allergist soon afterwards. Make sure you’ve identified the trigger and review your avoidance strategies and emergency action plan. It’s important to get a new adrenaline pen as soon as possible.


Our Anaphylaxis Emergency Response Kit comes with guides on how to recognise the symptoms of anaphylaxis, the use of an adrenaline pen and what you should do after. This makes it easier to know what to do in an emergency when you’re panicked or may need assistance from someone else before you receive medical attention.  It’s also a handy way to store and carry your meds.

Insulated EpiPen Case



Image Credit: Spencer

Disclaimer: The information provided is for informational purposes only and is not intended to be a substitute for professional medical advice, diagnosis or treatment. Allergy Lifestyle Limited (t/a) Allergy Lifestyle) uses reasonable endeavours to check the accuracy of information provided however no warranty is given that they are error-free.

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5 thoughts on “How long does anaphylaxis last?

  1. elizabeth says:

    Please cam anyone tell me how lpmg the rash continues after an anaphyletic attack..i am on my 4th day after treatment and am taking antihystmines. The rash isnt ichy anymore but looks more ir less the same with a little reduction in the redness. Thank you

  2. Bridie says:

    I was in Lydal one day and they had a container with scoops containing s variety of nuts these were left uncovered as the covers were broken I of course reported this and weeks later just the same android was not only in one store

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