The study, published in the Archives of Internal Medicine, found 89 percent of the labels listed the pharmacy name first and instructions fifth.

The study looked at labels for four drugs from chain, grocery store and independent pharmacies in four cities, and found the pharmacy name had an average 13.6-point font size. By comparison, medication instructions averaged a 9.3-point font size, medication names averaged an 8.9-point font, and warning stickers were 6.5-point font on average.

"Medical education guidelines explicitly suggest that font size must be 12 point or larger to optimize patients' ability to read health information," lead author Dr. William Shrank of Brigham and Women's Hospital said in a statement.

Jennifer Athay, a staff pharmacist with the American Pharmacists Association, said in a statement that a federally mandated, standardized label is difficult because containers are small.

"Size tends to be an issue, so the complete information you need to know is dispensed in the extra paperwork you get from the pharmacists," Athay said in a statement.