Adrenaline 1:1000 (1mg/mL) 0.5 mg IM (= 500 micrograms = 0.5 mL of 1:1000) should be given, (give IM unless experienced with IV adrenaline). Further doses can be given at about 5-minute intervals according to the patient's response.
Adrenaline auto-injectors, pre-assembled syringe with a needle suitable for rapid (IM) administration, are available for patients at risk of anaphylaxis.
After initial resuscitation:
Chlorphenamine 10mg injected slowly intravenously or intramuscularly may be given after the adrenaline. In the community, intramuscular injection may be used.
Hydrocortisone injection 200mg injected slowly intravenously or intramuscularly, taking care to avoid inducing further hypotension. Its onset of action is delayed for several hours, but it may prevent further deterioration in severely affected patients. In the community, intramuscular injection may be used.