Eli Lilly has initiated a crackdown to curb the trade of illicit forms of its investigational weight loss therapy, retatrutide, as around one in five patients turn to non-vetted sellers to source their medication.
As part of these efforts, Lilly has filed six lawsuits directed at US-based entities selling retatrutide products – including medical spas, compounding pharmacies and online sellers, which the Indiana-based pharma giant claims are advertising products for “research use only”. Lilly refutes this claim, alleging that the companies intend for them to be used in humans.
The pharma giant has flagged more than 200 individual sellers and entities to the US Food and Drug Administration (FDA) and the Department of Justice (DoJ), while reporting more than 14,000 online advertisements, social media posts, product listings and websites across more than 100 countries that it says are illegally marketing retatutide.
Lilly also points to the illegality of compounding retatrutide – a process where pharmacies custom-make unapproved medications with the same active ingredient as a branded drug when they are in short supply. Due to their lower price tag, patients are increasingly sourcing from compounding pharmacies despite the stable supply of medicines like Lilly’s Zepbound (tirzepatide) and Novo Nordisk’s Wegovy (semaglutide).
While the US Food and Drug Administration (FDA) has taken steps to crack down on illegal compounding, just under one in five patients are on a compounded weight loss medication, while 12% are unsure if their medication is branded, according to a survey by Gallup.
Cracking down on the illegal retatrutide trade is a logical next step for Lilly, which is looking to expand and preserve its highly successful weight loss empire underpinned by the tirzepatide franchise and new oral addition, Foundayo (orforglipron). In Q2, tirzepatide, marketed as Zepbound in obesity in the US and Mounjaro in type 2 diabetes globally and obesity outside the US, accounted for 64% of the drugmaker’s $23bn in revenue – besting analyst expectations.
According to a patient-based forecast from analysts at GlobalData, parent company of Pharmaceutical Technology, predicts that retatrutide will pull in $15.2bn in sales during 2031.
Stemming the retatrutide black market
While Lilly’s steps to curb the trade of black market retatrutide will likely have some immediate impact, the pharma titan calls for lasting change – which it says will rely on collaboration from several players.
This includes law enforcement and drug regulators, which the company says should treat the sale of unapproved medicines like retatrutide as an “urgent public health crisis”. Recently, the FDA sent out warning letters to a number of players in the illicit retatrutide trade, such as telehealth companies, active pharmaceutical ingredient (API) distributors and outsourcing facilities.
The Indiana-based pharma giant is also calling out social media and e-commerce platforms, which it claims may enable or fuel the illegal market, as well as credit card companies, logistics companies and payment processors that provide the infrastructure for illegal sellers to operate.
Over in the UK, there has also been a notable uptick in the large-scale production and sale of illicit retatrutide, with multiple raids occurring between 2025 and 2026 where around 2,000 unlicensed weight loss pens ready for shipping were seized on two separate occasions.
