Fluorine-containing medicines do not increase adverse drug reactions

Medicines containing a type of PFAS or 'forever chemical' called fluorine are not leading to higher numbers of adverse drug reactions according to new data analysis.

In a new paper published in PLOS ONE today, researchers from the University of Birmingham studied data from the MHRA's Yellow Card system on 13 drugs containing carbon-fluorine bonds as well as six drugs which were structurally similar but not containing this forever chemical.

Using five years of data from 2019-2024, the research team analysed the number of adverse drug reactions (ADRs) per 1 million medicines dispensed. They found that most of the ADRs that were listed for drugs containing fluorine were associated with conditions outside of the scope of usual side effects from PFAS, and the highest prescribed drug lansoprazole, a proton pump inhibitor to reduce stomach acid, had a low rate of 14.1 ADRs per 1m items.

Per- and poly-fluoroalkyl substances (PFAS) are often referred to as "forever chemicals" due to their persistence in the environment and effects on human health. PFAS are found in a range of everyday products such as cookware or clothing. Recent changes to the classification of PFAS means certain essential medicines are now deemed to contain forever chemicals.

In this study we explored adverse drug reactions reported to the MHRA Yellow Card scheme relative to their prescribing rate. Reassuringly, no statistical correlation between the fluorine content of the medicine and type of side effect emerged."

Dr. Alan Jones, School of Pharmacy, University of Birmingham and corresponding author of the paper

Among the 13 drugs selected for study, the team observed no relationship between the amount of fluorine atoms in the medicine and the number of ADRs reported. Among the drugs with the highest level of fluorine, sitagliptin and flecainide didn't see highest levels of reactions.

The team also looked at specific types of ADRs across the 13 fluorinated drugs studied, and found that while reactions have been associated with PFAS-like side effects, the comparison with non-fluorinated drugs suggests that the way the drug acted was more likely to result in that ADR.

The researchers note that limitations of the study include the self-reported nature of the Yellow Card system which could lead to underreporting of adverse drug reactions.