When you have been treated for anaphylaxis, you will be kept under clinical observation for at least four hours after the last injection of adrenaline. Adrenaline has a short duration of action and wears off quickly.
Occasionally, some people have another episode of anaphylaxis without coming in contact with their allergic trigger and require further treatment with adrenaline. This is called ‘biphasic anaphylaxis’. A clinician will review your risk of recurrence of anaphylaxis and re-exposure before you are discharged.
In some cases, you may need to be admitted overnight for observation after having anaphylaxis if:
- You have received more than one dose of adrenaline to treat your anaphylaxis
- You have a history of severe asthma
- You have arrived late in the evening
- You live alone or a long way from healthcare services
- Your adrenaline injector cannot be replaced before you get home and you do not have another one.