- Incidence: 20.00 cases per 100,000 person-years
- Peak incidence: 20-30 years
- Sex ratio: 1:1
- food (e.g. nuts) - the most common cause in children
- venom (e.g. wasp sting)
Adrenaline is by far the most important drug in anaphylaxis and should be given as soon as possible.
The recommended doses for adrenaline, hydrocortisone and chlorphenamine are as follows:
|< 6 months||150 micrograms (0.15ml 1 in 1,000)||25 mg||250 micrograms/kg|
|6 months - 6 years||150 micrograms (0.15ml 1 in 1,000)||50 mg||2.5 mg|
|6-12 years||300 micrograms (0.3ml 1 in 1,000)||100 mg||5 mg|
|Adult and child > 12 years||500 micrograms (0.5ml 1 in 1,000)||200 mg||10 mg|
Adrenaline can be repeated every 5 minutes if necessary. The best site for IM injection is the anterolateral aspect of the middle third of the thigh.
Management following stabilisation:
- patients who have had emergency treatment for anaphylaxis should be observed for 6–12 hours from the onset of symptoms, as it is known that biphasic reactions can occur in up to 20% of patients
- sometimes it can be difficult to establish whether a patient had a true episode of anaphylaxis. Serum tryptase levels are sometimes taken in such patients as they remain elevated for up to 12 hours following an acute episode of anaphylaxis.