How should acute urticaria be managed in a pregnant patient?

Treatment of Acute Urticaria in Pregnancy

Start with cetirizine 10 mg daily or loratadine 10 mg daily as first-line treatment, as these are FDA Pregnancy Category B second-generation antihistamines with the best safety profile for pregnant patients. 1, 2

First-Line Treatment: Second-Generation Antihistamines

• Cetirizine and loratadine are the preferred antihistamines because they have no evidence of fetal harm in animal studies and the longest safety record during human pregnancy. 1, 3
• Chlorphenamine (a first-generation antihistamine) is an acceptable alternative based on its long safety record in UK clinical practice, though it causes sedation. 1, 2
• Avoid all antihistamines during the first trimester if possible, though none has been proven teratogenic in humans. 1, 4
• Never use hydroxyzine during early pregnancy—it is specifically contraindicated. 1, 2

Dose Escalation Strategy

• If standard dosing provides inadequate control after 2-4 weeks, increase the antihistamine dose up to 4 times the standard dose (e.g., cetirizine 40 mg daily or loratadine 40 mg daily), weighing potential benefits against risks. 1, 5
• Escalation can occur earlier if symptoms are intolerable. 5, 1

Short-Course Corticosteroids for Severe Cases

• Limit oral prednisolone to short 3-day courses (50 mg daily) only for severe acute exacerbations that are intolerable. 1, 6
• Prednisolone is preferred over other corticosteroids because it is 90% inactivated by the placenta, minimizing fetal exposure. 5, 1
• Short tapering courses over 3-4 weeks may be necessary for severe cases, but avoid long-term use. 1

Adjunctive Non-Pharmacologic Measures

• Apply cooling antipruritic lotions such as calamine or 1% menthol in aqueous cream for symptomatic relief without systemic absorption. 1, 6
• Identify and eliminate aggravating factors including NSAIDs, aspirin, codeine, overheating, stress, and alcohol. 1, 2
• Use emollients to prevent skin dryness, avoid hot baths, and keep nails shortened to minimize scratching. 1

Emergency Management: Life-Threatening Presentations

• Administer intramuscular epinephrine 0.5 mL of 1:1000 solution (500 µg) immediately for anaphylaxis or severe laryngeal angioedema, even during pregnancy—this is life-saving. 1, 2
• Prescribe fixed-dose epinephrine auto-injectors (300 µg) for patients at risk of life-threatening attacks. 1, 2

Second-Line Treatment: Omalizumab

• For antihistamine-refractory cases, omalizumab 300 mg subcutaneously every 4 weeks can be considered, though data in pregnancy are limited. 5, 6
• Allow up to 6 months to evaluate response before considering alternatives. 5, 1
• Recent real-world data from 288 pregnant CU patients showed that 5.6% used omalizumab during pregnancy with no increased risk of preterm birth or neonatal problems. 7

Critical Safety Considerations

Common pitfalls to avoid:

• Do not use diphenhydramine as first-line treatment despite its frequent use—it has been associated with cleft palate development. 1
• Avoid oral decongestants during the first trimester due to conflicting reports of associations with gastroschisis and small intestinal atresia. 1
• Never use hydroxyzine in early pregnancy—this is an absolute contraindication. 1, 2

Real-World Pregnancy Outcomes

• A large international study of 288 CU patients during pregnancy found that 60% used urticaria medications, with 35.1% using standard-dose second-generation antihistamines. 7
• The preterm birth rate (10.2%) and rates of medical problems in newborns were similar to population norms and not linked to treatment used during pregnancy. 7
• More than 90% of newborns were healthy at birth regardless of maternal urticaria treatment. 7