Eli Lilly is planning a $3.5 billion factory in Pennsylvania to make the next generation of obesity injections

Eli Lilly said Friday it will spend more than $3.5 billion to build a factory in Pennsylvania’s Lehigh Valley that will help produce the next generation of obesity drugs.

That includes a closely watched experimental drug called retatrutide, which has shown the highest weight loss to date for any treatment in late-stage research.

It is the fourth facility in a series of new planned US investments by the pharmaceutical giant. Lilly announced in February 2025 that it would spend at least $27 billion to build new domestic manufacturing facilities, adding to the $23 billion in previous investments since 2020.

On Thursday, President Donald Trump said Lilly CEO Dave Ricks told him the drugmaker plans to do so build six factories in the US But Lilly has not confirmed those plans.

The company said Friday that it expects construction of the Pennsylvania plant to start this year and the site to be operational in 2031.

This extra production capacity for upcoming slimming treatments is crucial. Retatrutide is seen as a key pillar of Lilly’s long-term obesity strategy, following the popular Zepbound injection and the upcoming obesity pill.

Some health experts say retatrutide, which targets three gut hormones instead of one or two, could reach severely obese patients who would benefit from even more weight loss than what existing injections can provide. Lilly plans to release data from seven other Phase 3 trials of the drug this year.

The company and its main rival, Novo Nordiskhave invested heavily in increasing production capacity after previously facing supply shortages for their existing weekly injections in the US

Preparing an adequate supply of new drugs is also central to Lilly’s efforts to maintain its dominance in the booming GLP-1 market. The company secured the majority share in the sector for the first time last year, overtaking Novo.

But the Danish drugmaker hopes to close the gap with the launch of the first-ever anti-obesity GLP-1 pill this month, which has already attracted thousands of prescriptions in the US. Lilly has its own pill, orforglipron, which could win approval and hit the market later this year.

Drug makers are trying to ramp up production in the US following threats from President Donald Trump to impose tariffs on pharmaceutical products imported into the US. But concerns about those potential tariffs have subsided after voluntary price agreements with Trump in recent months exempted companies — including both Lilly and Novo — from the duties for three years.

Eli Lilly said the Pennsylvania location will bring 850 jobs to the area, including engineers, scientists, operations staff and laboratory technicians, as well as 2,000 construction jobs.