GlaxoSmithKline’s diet pill “alli” (pronounced al-EYE’), is now back in most U.S. stores.

The British drugmaker voluntary recalled the product last March after finding some packages in stores didn’t contain real alli, indicating tampering after shipment. The Food and Drug Administration is still investigating.

Glaxo’s (NYSE: GSK) innovation center for consumer products, in Parsippany, New Jersey, says the product package was redesigned to make tampering easier to spot.

“Nothing is more important than the health and safety of those who use our products. The alli® product will now feature additional tamper-evident packaging. It’s part of GSK Consumer Healthcare’s continued commitment to ensure the safety and quality of our products,” said Colin Mackenzie, president of GSK Consumer Healthcare North America, in announcing alli’s return. “We regret the inconvenience caused for our consumers and retailers, and we are very grateful for their patience as we worked diligently to bring alli back to market.”

Before shipping alli, known chemically as orlistat, to retail stores, Glaxo launched it in mid-February through and other online retailers.

Since late January, it’s been available for preorders on, where Glaxo says it was the top-selling diet item during the first pre-order week.

GlaxoSmithKline says alli is the only nonprescription diet medicine approved in the U.S. that’s proven to help people lose weight.