Pfizer Inc. (PFE) recalled 650,000 units of Advil Liqui-Gels in March because of an odor caused by over- processed gelatin.

The pills were recalled from stores by distributors in a March 16 letter sent by New York-based Pfizer, according to the U.S. Food and Drug Administration’s website. The gelatin is an inactive ingredient in the medicine, and over processing made the pills smell.

“It had a strong odor,” Jenifer Antonacci, a Pfizer spokeswoman, said in a telephone interview. “As soon as we found out about it, we isolated the issue and corrected it.”

Pfizer, the world’s largest drugmaker, isn’t the only one to experience quality issues with consumer pain relief products. On Feb. 17, Johnson & Johnson, based in New Brunswick, New Jersey, said it was pulling over a half-million bottles of infants’ Tylenol from shelves.

Pfizer gained less than 1 percent to $22.57 at the close of New York trading.

To contact the reporter on this story: Drew Armstrong in New York at darmstrong17@bloomberg.net

To contact the editor responsible for this story: Reg Gale at rgale5@bloomberg.net