A serious allergic reaction is called anaphylaxis. This is a medical emergency. If you suspect someone is experiencing anaphylaxis you should give them adrenaline straight away using an adrenaline pen.
Giving adrenaline
- Positioning is very important, the person experiencing anaphylaxis should be lying down with their legs raised. Always take the medication to them, they should never get up or walk to find help.
The videos below show you how to use an EpiPen and a Jext pen. Both brands do the same job but you use them slightly differently.
How to use an EpiPen
How to use a Jext pen
Symptoms of anaphylaxis
The main symptoms of anaphylaxis are often remembered by the initials ABC.
Airway
Problems with the airway may present as:
- Persistent coughing
- A hoarse voice
- Difficulty swallowing
- A swollen tongue
Breathing
Signs of breathing problems include:
- Noisy breathing
- Difficult breathing
- Wheezing
- Coughing
Circulation
Signs of problems with circulation or consciousness include:
- Feeling dizzy
- Going pale or floppy
- Becoming very sleepy
- Collapse or falling unconscious
If someone is experiencing anaphylaxis they will not always display signs of a less severe allergic reaction (eg. hives) first.
You can read more about the symptoms of allergic reactions here.
Steps for treating anaphylaxis:
LIE PERSON DOWN WITH LEGS RAISED
The person being treated should be lying down with their legs raised. If they are having trouble breathing they can sit. Small children may need to be held on your lap.
GIVE ADRENALINE
Use an adrenaline pen (adrenaline auto-injector) to deliver adrenaline into the upper, outer thigh muscle. Make a note of the time.
CALL 999
Call for an ambulance and say you are responding to anaphylaxis (pronounced: ANA_FILL_AXIS). This will trigger a priority response.
MONITOR AND PREPARE TO USE SECOND ADRENALINE PEN
If, after 5 minutes, the person having the allergic reaction is not showing signs of improvement or their symptoms are getting worse, give them another dose of adrenaline using a second adrenaline pen. Call 999 again and tell them you have administered a second dose of adrenaline.
STAY WITH PERSON AND KEEP THEM LYING DOWN
Do not let the person stand up and walk around, even if they are feeling better. They should stay lying down until the emegency services arrive. If they carry an inhaler, this can be used to reduce wheezing but give this after you have administered adrenaline.
Giving adrenaline FAQs:
If a second dose of adrenaline is needed, should it be given in the opposite thigh?
The most important thing is to deliver the second dose of adrenaline if needed. You can give the second dose in either leg.
Context: The question about whether it is better to give a second dose of adrenaline in the opposite leg to allow for maximum absorption of adrenaline was raised at the inquest into the death of Natasha Ednan-Laperouse.
At one of our Q&As Prof Adam Fox said
"When you give adrenaline it causes what's called vasoconstriction where it has been injected. This means that it narrows blood vessels in order to push the blood pressure up, which is what you're wanting the adrenaline to do. It pulls the blood supply away from the peripheries, i.e. your arms and your legs and particularly the area where the adrenaline was injected. So, if there's less blood supply going to that leg because you just put a slug of adrenaline in there, if you put another one in there's not going to be as much blood to pick it up and circulate it. So the suggestion is to use the other one. But this is not in current guidelines because there isn’t enough evidence to support it. So, it's not a problem at all putting it in the other one, but likewise it's no problem putting it in the same one. The important thing? Give the adrenaline five minutes later and worry less about which leg it's going into."
If someone recovers after receiving adrenaline do they still need to go to hospital?
Yes. Someone who has been given adrenaline should always go to hospital. They need to be monitored in case of a secondary allergic reaction. They also need to be prescribed with replacement adrenaline pens.
Will you notice other symptoms eg. hives before anaphylaxis occurs?
Not always. Allergic reactions do not always progress in a linear way from a mild to more serious situation. Anaphylaxis can happen very quickly without any prior symptoms related to a less serious reaction. As soon as you suspect any symptoms of anaphylaxis you should give adrenaline.
Reviewed March 2025 (AF)