As many as 1 in 8 American adults has tried one of the GLP-1 anti-obesity drugs, but a surprising number aren’t getting their supplies from pharma giants Novo Nordisk or Eli Lilly. Up to 30 percent of the market, by some estimates, is made up of copycat versions from compounding pharmacies.

Compounding is legal, though the resulting products sometimes fall into a gray area because they’re copies of drugs under patent and are not approved by the Food and Drug Administration.

Mark Mikhael, CEO of Orlando-based Olympia Pharmaceuticals, estimates that his and other large compounders provision up to 2 million Americans each month with semaglutide, the scientific name for Novo Nordisk’s Wegovy, Ozempic and Rybelsus formulations, or tirzepatide, the active ingredient in Eli Lilly’s Zepbound and Mounjaro.

Many of the compounded drugs are produced for and sold by online pharmacies like Hims & Hers Health, Henry Meds and Ro. Others come from smaller compounding companies.