INTRODUCTION Herbal medicines are used worldwide and with an increasing popularity in Western countries. Although often perceived as 'naturally safe', herbals may cause severe adverse drug reactions (ADRs), with immediate allergic reactions being particularly life threatening. OBJECTIVES The aim of this study was to analyse immediate allergy-like ADRs to herbals documented in VigiBase(®), the WHO international pharmacovigilance database. METHODS The documentation of all suspected ADRs in association with herbal exposure reported to VigiBase(®) from 1969 to August 2014 was retrieved. Among all reports in which WHO-ART reaction terms were indicative of acute allergic reactions, those classified as 'suspect' with a documented causality assessment and latency time of 1 day were selected. For the most frequent specific herbal-ADR combinations, the information component (IC) as a measure of disproportionality based on Bayesian statistics was calculated. RESULTS We identified 757 reports out of 1039 ADRs. Products with mixed herbals (36.0 %) as well as those administered orally (63.2 %) were predominant. The most frequent reactions were urticaria and rash (49.2 %). Anaphylactic reactions accounted for 9.5 %. Disproportionally frequent reporting of mouth edema (IC = 1.81) and anaphylactic reactions (IC = 1.24) to Phleum pretense were noted. CONCLUSION Our findings indicate that herbal medicines for oral use carry a risk of causing immediate allergy-like ADRs. Studies using the Vigibase(®) database can identify specific combinations of particular herbs and adverse reactions. Healthcare professionals and patients should be aware of these risks and report any serious adverse experiences. Results:We identified 757 reports with 1,039 ADR. Products with mixed herbals (36.0%) and oral administration (63.2%) were predominant. The most frequent reactions were urticaria and rash (49.2%).Anaphylactic reactions accounted for 9.5%. We found disproportionally frequent reporting of mouth oedema (IC=1.81) and anaphylactic reactions (IC=1.24) with Phleum pratense. Conclusion:Our findings indicate that herbal medicines for oral use carry a risk for allergy-like immediate ADR.Studies using the Vigibase ® database can identify specific combinations of particular herbs and adverse reactions. Health care professionals and patients should be aware of these risks and report any serious adverse experiences.

VigiBase contains a considerable number of acute hypersensitivity reactions in children associated with herbal medicines, including life-threatening reactions such as anaphylactic shock.