The Food and Drug Administration has approved changes to the Drug Facts label for the over-the-counter weight loss drug alli (orlistat) 60 mg capsules to warn about the risk of acute kidney injury and other kidney-related complications, the agency said in a drug safety communication last week.

The updated labeling advises consumers to consult a health care provider before using alli if they have ever had kidney disease or kidney stones. It also instructs users to stop taking the product and seek medical care if they develop symptoms that may indicate kidney injury or kidney stones, including back or groin pain, painful urination, blood in the urine, swelling in the feet or legs or decreased urination frequency.

The kidney injury warning is now described consistently across all FDA-approved orlistat products, including over-the-counter alli and the prescription-strength version Xenical (orlistat) 120 mg capsules.

The FDA said alli is approved for nonprescription weight loss in overweight adults 18 and older when used alongside a reduced-calorie and low-fat diet. It remains the only FDA-approved over-the-counter weight loss aid. Xenical is indicated for obesity management, including weight loss and weight maintenance, when used with a reduced-calorie diet and to reduce the risk for weight regain after prior weight loss.

Orlistat is a lipase inhibitor that works by binding to enzymes responsible for breaking down dietary fats, which reduces fat absorption in the digestive tract.

The agency noted rare reports of acute kidney injury, hyperoxaluria, calcium oxalate nephrolithiasis and oxalate nephropathy in people taking orlistat products. Acute kidney injury occurs when the kidneys suddenly cannot filter waste products from the blood, allowing harmful levels of waste to build up. Mild cases may be reversible, while severe untreated cases can be fatal. Hyperoxaluria involves high levels of oxalate in urine, a waste product made by the liver and obtained through diet. Calcium oxalate nephrolithiasis refers to kidney stones formed when oxalate combines with calcium in the urinary tract. Oxalate nephropathy occurs when calcium oxalate crystals form inside the kidneys and interfere with normal function.

Consumers with a history of kidney disease or kidney stones are advised to consult a health care provider before using alli. Those who experience possible symptoms of kidney injury or kidney stones should stop using the medication and seek medical care. The FDA also advised consumers experiencing side effects or poor response to the drug to speak with a health care provider about alternative treatment options.

Health care professionals are encouraged to inform patients seeking weight loss treatment about the rare but serious reports of kidney-related adverse events associated with orlistat products. If a patient using alli presents with signs of acute kidney injury or kidney stones, clinicians should advise discontinuation of the drug and proceed with appropriate evaluation and management.

The FDA continues to encourage consumers, patients and health care professionals to report adverse events or side effects associated with these products to the FDA’s MedWatch Safety Information and Adverse Event Reporting Program. Reports can be submitted online. Reporting forms can also be requested by phone at (1) 800-332-1088 and returned by mail or fax to (1) 800-FDA-0178.