For many people, particularly the elderly, the sick, and the poor, the beginning of the month means more money in one’s pocket. The influx of income goes hand-in-hand with a spike in prescription medication purchases.

It also coincides with a higher rate of deadly medication errors.

Researchers from the University of California, San Diego, have found that deadly prescription medication errors jump as much as 25% during the first few days of the month.

The first study of its kind shows that increased pharmacy workloads during this time are partly to blame. The findings are published in the January issue of Pharmacotherapy.

More government payments go out to the elderly, the sick, and the poor at the beginning of the month than any other time, resulting in a greater number of people flocking to pharmacies. As a result “pharmacy workloads go up and - in line with both evidence and experience - error rates go up as well. Our data suggest that the mortality spike occurs at least partly because of this phenomenon,” study author David P. Phillips, PhD, said in a press release.

Researchers combed through tens of thousands of death certificates from 1979 to 2000 and identified 131,952 deaths classified as fatal poisoning accidents due to prescription medications. The majority of incidents - 98.6% - occurred when the wrong drug was administered, too much of the drug was taken, or the drug was taken inadvertently. Phillips and his colleagues excluded suicides, homicides, and overdoses due to illegal street drugs.

Their analysis showed that the spike in fatal prescription medication errors was “higher than the spike for any other major cause of death.” The deaths did not vary by socioeconomic status.

The study authors write that, if future studies confirm their findings, spreading government payments out across the month and boosting pharmacy staff at the beginning of the month could help offset the risk for fatal errors. In addition, patients should always carefully check the accuracy of their medicines.

“If these preliminary changes are adopted, it seems plausible that some lives will be saved,” Phillips and colleagues conclude, in the journal report.