Spice allergens: Clinical relevance and cross-reactivity

Spices are widely used for culinary and medicinal purposes worldwide. Despite their widespread use, spice allergies, though relatively rare, are increasingly recognized and affect approximately 4–13 in every 10,000 adults, with higher prevalence among women, possibly due to cosmetic use. No prevalence data are currently available for children. This review delves into the clinical significance of spice allergens, discussing commonly allergenic spices, associated symptoms, and the diagnostic challenges they pose. Spice allergens are often degraded during digestion, making sensitization via IgE more common through inhalation, especially from cross-reactive pollens like mugwort and birch. Consequently, respiratory symptoms are frequently linked to inhalation, while skin contact can lead to cutaneous reactions. Diagnosis of spice allergies primarily relies on a detailed patient history and oral challenge tests, given the limited reliability of skin testing and specific IgE assays. Additionally, this review addresses the complexities of cross-reactivity, where structurally similar proteins in spices or related allergens (such as pollens or latex) can elicit immune responses in sensitized individuals. The frequent use of spice blends further complicates identification of specific allergens due to variability in blend composition. Understanding these mechanisms and risk factors is essential for accurate diagnosis, effective management, and preventive strategies for individuals affected by spice allergies.