Recognizing anaphylaxis
Anaphylaxis is likely in either of two situations: sudden skin or mucosal signs together with breathing difficulty, low blood pressure, collapse or severe gut symptoms; or, after a likely allergen, sudden low blood pressure, bronchospasm or throat involvement, even without skin signs.
Hives or itching with no other system involved is not anaphylaxis. Treat with an antihistamine and observe, and give IM epinephrine at once if breathing, circulation or gut symptoms appear.
IM epinephrine dose
Epinephrine is the only first-line treatment. Use epinephrine 1 mg/mL (1:1,000) at 0.01 mg/kg, which is 0.01 mL/kg, into the mid-anterolateral thigh. The maximum single dose is 0.5 mg. Repeat every 5 to 15 minutes if symptoms continue. Never delay epinephrine to give antihistamines or steroids.
| Weight | IM dose (mg) | Volume of 1 mg/mL | Autoinjector |
|---|---|---|---|
| 5 kg | 0.05 mg | 0.05 mL | Draw up 0.01 mg/kg (below 7.5 kg) |
| 10 kg | 0.1 mg | 0.1 mL | 0.1 mg |
| 15 kg | 0.15 mg | 0.15 mL | 0.15 mg |
| 20 kg | 0.2 mg | 0.2 mL | 0.15 mg |
| 25 kg | 0.25 mg | 0.25 mL | 0.15 mg |
| 30 kg | 0.3 mg | 0.3 mL | 0.3 mg |
| 40 kg | 0.4 mg | 0.4 mL | 0.3 mg |
| 50 kg | 0.5 mg | 0.5 mL | 0.3 mg |
| 60 kg | 0.5 mg (max) | 0.5 mL | 0.3 mg |
Autoinjector dose by weight
When drawing up a dose is not possible, use an autoinjector in the same thigh site and repeat in 5 to 15 minutes if needed.
- Below 7.5 kg: draw up 0.01 mg/kg instead
- 7.5 to under 15 kg: 0.1 mg
- 15 to under 30 kg: 0.15 mg
- 30 kg or more: 0.3 mg
First steps and supportive care
For hypotension or poor perfusion, give a 20 mL/kg 0.9% saline bolus IV (maximum 1,000 mL), repeated up to 60 mL/kg. For bronchospasm after epinephrine, nebulized albuterol 2.5 mg under 20 kg or 5 mg at 20 kg or more, repeated as needed. Antihistamines treat only itch and hives, and glucocorticoids are not recommended routinely to prevent biphasic reactions.
- Give IM epinephrine immediately
- Lay the child flat with legs raised; sit up if breathing is hard; do not let the child stand or walk
- Give oxygen, start monitoring and get IV access
- Remove the trigger, for example stop an infusion or remove a stinger
If symptoms persist after 2 doses
Anaphylaxis that is still present or worse after 2 doses of IM epinephrine 5 to 15 minutes apart is refractory. Start an epinephrine infusion at 0.1 to 1 mcg/kg/min, titrated to blood pressure and symptoms. A child on a beta-blocker can be given glucagon 20 to 30 mcg/kg IV over 5 minutes (maximum 1 mg), then an infusion of 5 to 15 mcg/min. Repeat fluid boluses, add vasopressors if still hypotensive, and admit to intensive care.
Observation and discharge
Observe for at least 4 to 6 hours after symptoms resolve, and longer, or admit, if 2 or more doses were needed or the reaction was severe. A severe reaction means admission or extended observation.
Discharge with 2 epinephrine autoinjectors of the right strength, a written action plan and teaching, and refer to an allergist with advice to avoid the trigger. A serum tryptase 30 minutes to 2 hours after onset helps if the diagnosis is uncertain.
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Recognition, IM epinephrine and autoinjector doses by weight, refractory treatment and discharge.
Open Anaphylaxis →Common questions
What is the epinephrine dose for a child with anaphylaxis?
0.01 mg/kg IM of the 1 mg/mL solution (0.01 mL/kg), maximum 0.5 mg, into the outer thigh. It can be repeated every 5 to 15 minutes.
Which autoinjector strength does my child need?
0.1 mg for 7.5 to under 15 kg, 0.15 mg for 15 to under 30 kg, and 0.3 mg for 30 kg or more. Below 7.5 kg, a dose of 0.01 mg/kg is drawn up instead.
Should antihistamines be given first?
No. Epinephrine comes first and should never be delayed. Antihistamines only treat itch and hives, not airway problems or shock.
How long should a child be watched after anaphylaxis?
At least 4 to 6 hours after symptoms resolve, and longer or with admission if 2 or more epinephrine doses were needed or the reaction was severe.
Sources
Golden DBK, Wang J, Waserman S, et al. Anaphylaxis: a 2023 practice parameter update. Ann Allergy Asthma Immunol 2024;132(2):124-176.; Cardona V, et al. World Allergy Organization anaphylaxis guidance 2020. World Allergy Organ J 2020;13:100472.
For education only, not medical advice. Always confirm against current guidelines and your local protocols. Pedemy is independent and not affiliated with or endorsed by the organizations cited.