Over the past year, prices for many generic drugs have been climbing, prompting concerns that a low-cost staple of the U.S. health care system might soon strain budgets. And two new reports indicate that prices continued to rise during the first quarter of this year, but not at the same rapid rate that was seen at times in 2014.

One report shows that the prices paid by retailers rose 4.7%, which was nearly in line with the 5.1% percent average price increase over the past two years, according to Sector & Sovereign Research....