Eli Lilly & Co. is suing four telehealth companies selling compounded versions of Lilly's weight-loss drug Zepbound and its diabetes drug Mounjaro.

Eli Lilly ( LLY 0.89%) has been growing its sales at a good clip over the past year. This is partly thanks to Zepbound, a weight loss medicine that's already generating more than $1 billion in quarterly sales, although it was approved only in late 2023.

Eli Lilly Wednesday filed lawsuits against four telehealth companies alleging they are deceiving consumers by selling compounds of slightly-different versions of Lilly drugs.