Conclusion
Although, except in long-term use, PPIs are generally well tolerated, their widespread use has been associated with immediate and delayed HSRs, some of which might be life threatening. Correct identification of PPI HSRs and of safe alternative drugs for future use is crucial to prevent severe drug reactions and unnecessary avoidance of the whole PPI group. Skin tests are useful in diagnosing immediate HSRs to PPIs, however, their sensitivity is low. There is a substantial cross-reactivity between PPIs, which can be assessed first by skin testing and subsequently by DPT in immediate HSRs. Cross-reactivity rates between PPIs in immediate type HSRs are analyzed according to the available studies and are given in the current PP to guide the selection of possible alternative PPIs for diagnostic tests. Although rarely reported we need to be aware of the potential whole group cross-reactivity in the setting of both immediate and non-immediate PPI HSRs. Data regarding delayed PPI HSRs are limited. There are several unmet needs that require further research in this topic and greater knowledge on the management of PPI induced HSRs.