Treatment of Allergic Reaction with Itching and Shortness of Breath
Inject intramuscular epinephrine immediately into the mid-outer thigh—this is the only first-line treatment for anaphylaxis and must never be delayed or replaced by antihistamines. 1, 2, 3
Immediate Recognition and Action
The combination of itching (skin manifestation) and shortness of breath (respiratory involvement) represents anaphylaxis, a life-threatening systemic allergic reaction requiring immediate treatment. 1
Critical first steps:
- Administer epinephrine 0.3-0.5 mg intramuscularly (1:1000 concentration) for adults immediately 1, 2, 3, 4
- For children: 0.01 mg/kg (maximum 0.3 mg for prepubertal children, 0.5 mg for adolescents >50 kg) 3
- Inject into the vastus lateralis (mid-outer thigh) for optimal absorption 2, 3
- Call 911 or activate emergency medical services simultaneously 3
- Position patient supine with legs elevated (unless vomiting or severe respiratory distress prevents this) 3
Why Epinephrine Must Come First
Delay in epinephrine administration is directly associated with anaphylaxis fatalities and increased risk of biphasic reactions. 2 Epinephrine works immediately through multiple mechanisms: vasoconstriction, bronchodilation, positive inotropic effects, and mast cell stabilization—none of which antihistamines or other adjunctive medications can provide. 2, 5
The American Heart Association guidelines emphasize that in anaphylactic shock, epinephrine should take priority over all other interventions, with standard BLS and ACLS measures as needed. 1
Adjunctive Treatments (Only AFTER Epinephrine)
These medications are supplementary and should never delay or replace epinephrine: 1
H1 Antihistamines
- Diphenhydramine 25-50 mg IV or orally can be given after epinephrine 1, 6
- These only address itching and urticaria—they do NOT treat shortness of breath, airway swelling, or cardiovascular collapse 1, 2
- Onset of action is 30-60 minutes, far too slow for acute anaphylaxis 2
- Critical pitfall: First-generation antihistamines cause sedation that can mask worsening symptoms 1, 2
Bronchodilators
- Albuterol nebulizer or MDI for persistent bronchospasm not responsive to epinephrine 1, 3
- Important limitation: Albuterol does NOT relieve laryngeal edema or airway swelling 1
Supplemental Oxygen
- Provide to all patients with respiratory symptoms 3
IV Fluid Resuscitation
Repeat Dosing and Monitoring
- Epinephrine can be repeated every 5-15 minutes if symptoms persist or recur 1
- A second dose should be considered if the patient remains symptomatic 5 minutes after the first injection 1
- Monitor continuously for biphasic reactions (recurrence without re-exposure) 1, 7
Critical Pitfalls to Avoid
Never use antihistamines or inhalers as first-line treatment—this is a dangerous practice that delays life-saving epinephrine. 1, 2 The NIAID expert panel explicitly states: "Asthma inhalers and/or antihistamines cannot be depended on in anaphylaxis." 1
Never allow the patient to stand, walk, or run—this can precipitate cardiovascular collapse. 3
Do not rely on corticosteroids for acute treatment—they have a 4-6 hour onset of action and do not prevent biphasic reactions. 1, 2
Observation and Transfer
- All patients must be transferred to an emergency department, preferably by EMS 3
- Observe for minimum 4-6 hours after successful treatment 3, 7
- Prolonged observation warranted for severe reactions, history of biphasic reactions, or patients with asthma 3
Discharge Planning
Before discharge from emergency care:
- Prescribe two epinephrine autoinjectors with proper training 3
- Provide written anaphylaxis emergency action plan 1, 3
- Refer to allergist for evaluation and identification of trigger 3, 7
High-Risk Populations
Patients with coexisting asthma (like this patient with shortness of breath), adolescents/young adults, previous anaphylaxis history, and peanut/tree nut allergies are at increased risk for severe or fatal reactions and require heightened vigilance. 3, 7