Merck’s drug for chemo-induced nausea and vomiting has some new competition.

On Thursday, the FDA approved Cinvanti from California’s Heron Therapeutics, and it’ll go up against the New Jersey pharma giant’s Emend. The two drugs, which share an active ingredient, will go at it in a patient pool drawing from the 4 million people who receive chemo each year, Heron said.

While the Merck drug comes along with more delivery options—patients can take Emend as an injection or in capsule form, while Cinvanti is an IV product—it may also come with more side effects. Unlike Emend, Cinvanti doesn’t contain polysorbate 80, which can cause allergic reactions—including anaphylaxis—and infusion-site reactions.

It’s the second FDA approval in 15 months for Heron, which last August won a green light for fellow nausea and vomiting drug Sustol. The regulatory win was a big one for the company, which had already seen two applications rejected over a period of about 6 years.

And now, Heron has injectable therapies that complement one another, with each addressing one of the primary mechanisms of chemo-induced nausea and vomiting. "They are an excellent strategic and operational fit for the Heron commercial team," Heron CEO Barry Quart, Pharm.D., said in a statement, adding that Cinvanti was on track for a January launch.

Merck, meanwhile, will be working to protect sales of Emend that checked in at $549 million last year. So far for 2017, the drug has racked up $413 million after posting $137 million in the third quarter.