Almost all oral medications contain at least one inactive ingredient known to cause an allergic reaction in susceptible patients, an investigation by US academics has found.

Inspired to act when a patient with coeliac disease became sick after taking a PPI containing gluten, the team, led by the Brigham and Women’s Hospital and Massachusetts Institute of Technology, set out to determine how many drugs contain potential allergens.

Their analysis of a database of 42,000 oral medications and other data has unearthed nine key findings, published in Science Translational Medicine:

Corresponding author Dr Giovanni Traverso, a gastroenterologist at Brigham, says a striking finding is the number of different combinations of inactive ingredients in medications with the same therapeutic effect.