A bipartisan group of 81 U.S. lawmakers has asked the Food and Drug Administration to intensify enforcement against pharmacies and telehealth providers selling compounded or counterfeit versions of GLP-1 receptor agonists, the class of drugs behind the weight-loss boom. In a letter sent on Friday, the legislators cited mounting safety concerns and urged the agency to use its recall authority and other tools to remove unapproved products from the market. The lawmakers asked the FDA to provide an update by July 30 on actions it has taken, including inspections, warning letters and referrals to the Justice Department. They said patients may be exposed to formulations that lack proven efficacy or proper dosing, potentially undermining confidence in approved brands such as Eli Lilly’s Zepbound and Novo Nordisk’s Wegovy. Shares of Eli Lilly rose after the letter became public, while Hims & Hers Health—which offers compounded versions of semaglutide—fell from a roughly 3% gain to a 2% loss. Novo Nordisk shares were little changed. Analysts said a tougher enforcement stance could benefit manufacturers of FDA-approved drugs by curbing lower-cost imitators.