Treatment algorithm

Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer

ACUTE

anaphylactic reaction

1st line – airway management and oxygen

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ACUTE
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anaphylactic reaction
1st line – 

airway management and oxygen

Airway management and oxygenation supersedes all other aspects of management.

Endotracheal intubation may be necessary in severe cases of upper airway obstruction.

Plus – epinephrine

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ACUTE
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anaphylactic reaction
Plus – 

epinephrine

Treatment recommended for ALL patients in selected patient group

Epinephrine given by intramuscular injection in the lateral thigh is the treatment of choice for significant systemic symptoms.

Any symptoms of anaphylaxis, such as systemic reaction of pruritus, erythema, urticaria, and angioedema alone, and any other systemic symptom including those not involving vital organs, should be treated immediately and as necessary with appropriate doses of intramuscular epinephrine in an attempt to prevent more severe anaphylaxis from occurring.[82]​​[83]

Confusion, syncope, hypotension, and shock necessitate laying the person flat with their legs elevated.

Primary options

epinephrine (adrenaline): children: 0.01 mg/kg (1:1000 solution) intramuscularly every 5 minutes; adults: 0.3 to 0.5 mg (1:1000 solution) intramuscularly every 10-15 minutes

Plus – intravenous fluids

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ACUTE
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anaphylactic reaction
Plus – 

intravenous fluids

Treatment recommended for ALL patients in selected patient group

Appropriate venous access is required to allow high-volume fluid resuscitation (e.g., lactated Ringer solution or isotonic saline) of shock and bolus intravenous administration of medication.

Consider – corticosteroid

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ACUTE
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anaphylactic reaction
Consider – 

corticosteroid

Treatment recommended for SOME patients in selected patient group

Use of corticosteroids to limit biphasic anaphylaxis is controversial; evidence to support their use is lacking.[51]​[84]​​

Primary options

methylprednisolone sodium succinate: children and adults: 1-2 mg/kg/day intravenously

Consider – vasopressor

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ACUTE
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anaphylactic reaction
Consider – 

vasopressor

Treatment recommended for SOME patients in selected patient group

Vasopressors may be required to treat persistent hypotension associated with anaphylaxis.[51] Seek advice from critical care specialists.

Consult specialist for guidance on choice of regimen and dose.

Consider – glucagon

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ACUTE
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anaphylactic reaction
Consider – 

glucagon

Treatment recommended for SOME patients in selected patient group

Used in patients taking beta-blockers and not responsive to epinephrine.[51]

Glucagon is thought to reverse refractory hypotension and bronchospasm by activating adenylate cyclase independent of the beta-receptor; however, the occurrence and importance of this mechanism of action in anaphylaxis is unproved.

Airway protection must be ensured because glucagon frequently causes emesis.[85]

Primary options

glucagon: see local protocol for dosing guidelines

Consider – atropine

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ACUTE
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anaphylactic reaction
Consider – 

atropine

Treatment recommended for SOME patients in selected patient group

Blocks the action of acetylcholine at parasympathetic sites in smooth muscle, secretory glands, and the central nervous system; increases cardiac output, dries secretions.

Atropine reverses the muscarinic effects of cholinergic poisoning. The primary goal in cholinergic poisonings is reversal of bronchorrhea and bronchoconstriction.

Atropine has no effect on the nicotinic receptors responsible for muscle weakness, fasciculations, and paralysis.

In patients with anaphylaxis it may be used to treat symptomatic bradycardia.[51]

Primary options

atropine: children: 0.02 mg/kg intravenously every 5 minutes when required, maximum 1 mg/total dose; adults: 0.5 to 1 mg intravenously every 5 minutes when required, maximum 2 mg/total dose

Consider – cardiopulmonary resuscitation

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ACUTE
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anaphylactic reaction
Consider – 

cardiopulmonary resuscitation

Treatment recommended for SOME patients in selected patient group

For cardiopulmonary arrest during anaphylaxis, high-dose epinephrine and prolonged resuscitation efforts are encouraged, if necessary.[84]

cutaneous symptoms

1st line – antihistamine + H2 antagonist

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ACUTE
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cutaneous symptoms
1st line – 

antihistamine + H2 antagonist

Diphenhydramine, an antihistamine, competes with histamine for H1-receptor sites on effector cells in the gastrointestinal tract, blood vessels, and respiratory tract. Oral antihistamines may not be effective in more severe allergic reactions because they are relatively slow to act and principally relieve cutaneous symptoms rather than the cardiorespiratory problems that make anaphylaxis a life-threatening emergency.[84]

H2 antagonists (e.g., cimetidine) work by competitive inhibition of histamine at H2-receptors of the gastric parietal cells, which inhibits gastric acid secretion and reduces gastric volume and hydrogen ion concentration. Do not affect pepsin secretion, pentagastrin-stimulated intrinsic factor secretion, or serum gastrin.

Treatment with a combination of an antihistamine H1 and H2 antagonist has been reported to be more effective in lessening the cutaneous manifestations of anaphylaxis than treatment with antihistamines alone.[85]

Primary options

diphenhydramine: children: 5 mg/kg/day orally/intravenously given in divided doses every 6-8 hours, maximum 300 mg/day; adults: 25-50 mg orally/intravenously every 6-8 hours when required, maximum 400 mg/day

and

cimetidine: children: consult specialist for guidance on dose; adults: 300 mg intravenously as a single dose

bronchospasm

1st line – bronchodilator

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ACUTE
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bronchospasm
1st line – 

bronchodilator

Bronchodilators are effective when wheezing is present, and may be given in a nebulized form with supplemental oxygen if needed.[51]

Relaxes bronchial smooth muscle by action on beta-2 receptors with little effect on heart rate.

For purposes of differentiating local versus systemic reactions, anaphylaxis herein is defined as an acute, severe, life-threatening allergic reaction in presensitized people, leading to a systemic response caused by the release of immune and inflammatory mediators from basophils and mast cells.

Primary options

albuterol inhaled: (90 micrograms/dose metered dose inhaler) children and adults: 360-720 micrograms (4-8 puffs) every 20 minutes for 3 doses, then every 4-6 hours when required

OR

albuterol inhaled: children: 0.15 mg/kg nebulized every 20 minutes for 3 doses, then every 1-4 hours when required; adults: 2.5-5 mg nebulized every 20 minutes for 3 doses, then every 1-4 hours when required

rhinoconjunctivitis

1st line – antihistamine

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ACUTE
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rhinoconjunctivitis
1st line – 

antihistamine

Treatment with oral antihistamine is sufficient.

Primary options

diphenhydramine: children: 5 mg/kg/day orally/intravenously given in divided doses every 6-8 hours, maximum 300 mg/day; adults: 25-50 mg orally/intravenously every 6-8 hours when required, maximum 400 mg/day

ONGOING

following stabilization

1st line – avoidance and allergy action plan

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ONGOING
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following stabilization
1st line – 

avoidance and allergy action plan

Ingestion of hidden ingredients is a particular concern. For example, milk may be variously listed as casein, whey, caseinate, or lactalbumin. Food allergy education for patients and caregivers is vital.

Intervention at the first sign of a severe allergic reaction offers the best chance of resolution. The most common manifestations of an allergic reaction involve cutaneous, respiratory, and gastrointestinal symptoms.

At minimum, patients and caregivers should know where to locate and how to activate public emergency notification systems.

An individualized written allergy action plan may be beneficial to patients, parents/caregivers, and healthcare providers in preparing for treatment of an allergic reaction to food.[80]​​ AAP: allergy and anaphylaxis emergency plan Opens in new window

Plus – portable epinephrine auto-injectors for home use

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ONGOING
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following stabilization
|
with anaphylactic episode
Plus – 

portable epinephrine auto-injectors for home use

Treatment recommended for ALL patients in selected patient group

A prescription for two epinephrine auto-injectors must be given after any episode of anaphylaxis.[86][89] The patient or carer should carry both at all times and be familiar with their use.​[83]

Primary options

epinephrine (adrenaline): children <30 kg body weight: 0.15 mg intramuscularly as a single dose; children ≥30 kg body weight and adults: 0.3 mg intramuscularly as a single dose

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Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups. See disclaimer

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