From the Guidelines
Vomiting is a red flag in a pediatric patient with moderate urticaria without angioedema or wheeze, as it may indicate progression to anaphylaxis, according to the 2020 practice parameter update on anaphylaxis 1. This is because vomiting suggests gastrointestinal involvement, which is one of the organ systems affected during systemic allergic reactions. When a child with urticaria develops vomiting, it warrants immediate medical attention and consideration of epinephrine administration. Key points to consider in this scenario include:
- The presence of vomiting alongside urticaria represents multisystem involvement, which is a critical factor in diagnosing anaphylaxis 1.
- The recommended dose of epinephrine for children is 0.01 mg/kg of 1:1000 (1 mg/mL) solution, with a maximum of 0.3 mg for children under 30 kg and 0.5 mg for those over 30 kg, administered intramuscularly in the mid-outer thigh.
- Even if other anaphylaxis symptoms like respiratory distress or hypotension are absent, vomiting alongside urticaria should prompt emergency treatment due to the risk of anaphylaxis 1.
- After initial management, the child should be observed for at least 4-6 hours as biphasic reactions can occur. Gastrointestinal symptoms in allergic reactions result from mast cell degranulation in the gut mucosa, releasing histamine and other inflammatory mediators that cause smooth muscle contraction and increased secretions, leading to symptoms like vomiting, abdominal pain, and diarrhea, as outlined in the anaphylaxis practice parameter update 1.
From the Research
Urticaria and Angioedema in Pediatrics
- Urticaria and angioedema are common occurrences in the pediatric population, with multiple causes of acute and chronic urticaria and angioedema 2.
- The diagnosis of urticaria in children can be challenging, as it can be triggered by numerous conditions, including viral infections, foods, insect stings, and medical diseases 3.
Red Flags in Pediatric Urticaria
- Vomiting is not explicitly mentioned as a red flag in pediatric patients with moderate urticaria without angioedema or wheeze in the provided studies.
- However, it is crucial to differentiate cases of chronic urticaria from mastocytosis and Bradykinin-mediated angioedema, as treatment may differ 3.
- Chronic urticaria could rarely be a presentation of vasculitis, systemic-onset juvenile idiopathic arthritis, or auto-inflammatory syndromes, making it essential to rule out these conditions 3.
Management of Urticaria and Angioedema
- Second-generation antihistamines are considered first-line agents in the treatment of chronic urticaria due to their safety and efficacy profile 4.
- The management of chronic urticaria in children has improved over the last decade with the development of clear management guidelines and new effective drugs 3.
- Angioedema is still best classified by whether it is likely histaminergic or kinin-mediated, and new guidelines have been published to help diagnose and treat both forms 5.