Although most adverse drug reactions are caused by the active substances, excipients may sometimes affect the safety profile of a medicinal product.

The aim of this review is two-fold: (1) To identify the excipients most frequently contained in oral medicinal products marketed in Italy for gastrointestinal indications, and to evaluate the main safety concerns, considering both intrinsic toxicity and patient-related risk factors. (2) To analyse possible differences with medicinal products marketed in the United Kingdom and USA in terms of excipients and relevant warnings reported in the label.

We identified excipients with a potential impact on the safety profile and calculated the frequency of use of each of the excipients identified in 98 selected medicinal products.  We discuss possible safety concerns in clinical practice.  We also analysed the US and UK Summary of Product Characteristics (SmPC) of oral gastrointestinal products by searching in appropriate collections of regulatory agencies.

Eleven excipients with a safety impact were identified (sucrose, saccharin, aspartame, sorbitol, mannitol, lactose, ethanol, propylene glycol, parabens, menthol and silica) and no substantial differences were found between drugs marketed in the three countries concerning excipient content.

Warnings were more detailed in the SmPC of UK or USA products compared with Italian products.

Information about pharmaceutical excipients with known effects is important in clinical practice, but the frequent lack of details in the related section of the SmPCs makes it difficult for health professionals to provide relevant advice.

The availability of alternative products of the same therapeutic class, but lacking specific excipient(s) should be considered in selected patients.