What are the recommended guidelines for evaluating and treating acute urticaria (hives) in an 18‑month‑old child?

Management of Acute Urticaria in an 18-Month-Old Child

For an 18-month-old with acute urticaria, start with a non-sedating H1 antihistamine at standard pediatric dosing after consulting the specific product data sheet for age-appropriate formulations, as dosing and age restrictions vary for children under 12 years. 1

Initial Assessment

Clinical Diagnosis

• Diagnosis is primarily clinical and does not require routine laboratory testing in acute urticaria 1, 2
• Confirm that individual wheals resolve within 2-24 hours without scarring, which is characteristic of ordinary urticaria 2
• If wheals persist beyond 24 hours, suspect urticarial vasculitis and consider dermatology referral 2

History-Guided Evaluation

Focus your history on:

• Recent viral infections (the most common trigger in pediatric acute urticaria) 3, 4
• Food exposures (especially nuts, fish, eggs, milk) 1, 3
• Medication use within the past 24-48 hours 3, 4
• Insect stings or bites 4
• Contact with latex or chemicals 1, 3

When to Investigate

• No laboratory tests are needed for typical acute urticaria unless the history suggests a specific trigger 1, 2
• If IgE-mediated food or environmental allergy is suspected based on history, consider skin-prick testing or CAP fluoroimmunoassay, but interpret results in clinical context 1, 2

Treatment Approach

First-Line Therapy

• H1 antihistamines are the cornerstone of treatment 1, 3
• Critical caveat: Check the specific product data sheet before prescribing, as dosing and age restrictions vary significantly for children under 12 years 1
• None of the currently licensed antihistamines is contraindicated in children 12 years and older, but younger children require individualized product selection 1

Adjunctive Measures

• Short-course oral corticosteroids (e.g., prednisolone) may shorten the duration of acute urticaria, though lower doses than the adult standard (50 mg daily for 3 days) are often effective in children 1
• Cooling antipruritic lotions such as calamine or 1% menthol in aqueous cream can provide symptomatic relief 1

Avoiding Aggravating Factors

• Minimize overheating, stress, and alcohol exposure 1
• Avoid aspirin and NSAIDs, as these can worsen urticaria through direct mast cell degranulation 1
• Avoid codeine and other opioids that can cause direct mast cell degranulation 5

Emergency Management

Signs Requiring Immediate Intervention

• Laryngeal angioedema or anaphylaxis requires intramuscular epinephrine 1
• For children weighing 15-30 kg (which includes most 18-month-olds), use a 150 µg fixed-dose epinephrine pen 1
• Parenteral hydrocortisone is often given as an adjunct for severe laryngeal edema, though its action is delayed 1
• If symptoms do not significantly improve after the first epinephrine dose, give a second dose 1

When to Prescribe an Epinephrine Autoinjector

• Consider prescribing an epinephrine pen for home use if the history indicates risk of recurrent life-threatening attacks 1

Red Flags Requiring Further Evaluation

Systemic Symptoms

• Fever with urticaria should prompt consideration of autoinflammatory syndromes (such as Cryopyrin-associated periodic syndromes) rather than simple acute urticaria 6, 4
• Joint involvement, renal symptoms, or wheals lasting days suggest urticarial vasculitis 5, 4

Chronic Course

• If urticaria persists beyond 6 weeks, it becomes chronic urticaria and requires a different diagnostic and therapeutic approach 4, 7
• Chronic urticaria in children is unlikely to have an identifiable external trigger and should be managed with escalating antihistamine doses 8

Common Pitfalls to Avoid

• Do not perform extensive laboratory workups for typical acute urticaria—this is unnecessary and not cost-effective 1, 2
• Do not use long-term oral corticosteroids for urticaria management—these should be reserved only for very selected cases under specialist supervision 1
• Do not assume all urticaria is allergic—viral infections are the most common trigger in this age group 3, 4
• Remember that H2 antihistamines may be added to H1 antihistamines for better control, though evidence for this practice is limited and it may be more helpful for accompanying dyspepsia 1