Topline
The Food and Drug Administration is warning against new side effects of Haleon’s over-the-counter weight loss drug Alli, the only such medication currently available in the U.S. without a prescription, and has approved a new label for the drug that highlights potential kidney problems.
A pack of Alli at a pharmacy in London.
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Key Facts
The agency approved changes to the drug facts label of Alli’s 60 mg capsules to warn of rare risks on Wednesday, including acute kidney injury, kidney stones and oxalate nephropathy, a deposit of calcium oxalate crystals into the kidney tubule that can cause kidney injury and potential fibrosis.
The updated label now instructs consumers with a history of kidney disease or kidney stones to consult a doctor before use, and directs all users to stop taking Alli if they develop back or groin pain, blood in the urine, painful urination or leg swelling.
The FDA warned severe untreated cases of acute kidney injury—defined as a kidney’s sudden inability to filter waste products from the blood—can be fatal.
Alli’s drug facts label already warned against taking the medication for those who’ve had an organ transplant and advises those with gallbladder problems, pancreatitis or who take certain medications for diabetes, clotting or thyroid disease consult a doctor before use.
BIG NUMBER
40 million. That’s how many people are estimated to have taken orlistat (available as Alli or the prescription version Xenical) since Xenical was approved by the FDA in 1999. Alli, the lower-dose, over-the-counter version, was approved in 2007.
CONTRA
Though Alli, the brand name of the generic drug orlistat, is available without a prescription, the FDA, Mayo Clinic, British NHS and some high-profile doctors have warned against taking Alli without the supervision of a healthcare professional. Medical experts have largely raised concerns about drug interactions; risk of vitamin deficiencies; gastrointestinal side effects; serious liver, kidney, and gallbladder complications; or misuse by people with eating disorders and unhealthy weight-loss behaviors.
CRUCIAL QUOTE
“These drugs have the potential to cause significant damage to multiple critical organs, yet they provide meager benefits in reducing weight loss in obese and overweight patients,” Dr. Sidney Wolfe, former director of Public Citizen’s Health Research Group, told ABC News.
Key background
The United States is in the middle of a weight-loss drug boom thanks to the increasing popularity of GLP-1 medications like Wegovy, Ozempic, and Zepbound, but Alli played a different role in the history of weight-loss medications. When the FDA approved Alli in 2007, it became the first over-the-counter weight-loss drug in U.S. history, a title it still holds today. While GLP-1 drugs work by suppressing appetite, Alli works by blocking the absorption of some dietary fat. Orlistat generally produces more modest results, but it also helped normalize the idea that millions of Americans would seek pharmaceutical help to lose weight, if it was widely available and considered safe.
SURPRISING FACT
Polling by KFF found that about 1 in 8 U.S. adults were taking a GLP-1 drug by late 2025, roughly twice as many as in 2024.