Background
There is a high use of medications in adults with intellectual disability (ID). One implication of taking multiple medications is the potential for drug–drug interactions (DDIs). However, despite this being well highlighted in the mainstream literature, little is known about the incidence or associations of DDIs in the ID population.

Methods
This study describes the prevalence, patterns and associations of potential DDIs in a total administrative sample of adults with ID known to services in Jersey. Demographic, health‐related and medication data were collected from 217 adults known to ID services. Data were collected using a face‐to‐face survey. The Anatomical Therapeutic Chemical classification system was used to categorise medications, and Stockley's Drug Interaction Checker was used to classify potential DDIs. Drug–drug pairings were considered to be of clinical significance if they were to be ‘avoided, adjusted, monitored or required further information’.

Results
Potential DDIs of clinical significance were common. Exposure to potential DDIs of clinical significance was associated with being female, taking more than five medications (polypharmacy), living in residential care and having more health conditions. A simple regression was used to understand the effect of number of prescribed medications on potential DDIs of clinical significance. Every prescribed drug led to a 0.87 (95% confidence interval: 0.72–1.00) increase in having a potential DDI of clinical significance.

Conclusion
Adults with ID who live in residential care, who are female, exposed to polypharmacy and have more health conditions may be more likely to have potential DDIs of clinical significance. Urgent consideration needs to be given to the potential of DDIs in this population given their exposure to high levels of medication.