GlaxoSmithKline’s OTC allergy medication Flonase generated almost $100 million in sales during its first 16 weeks on the market, according to data from marketing firm IRI that was published by Drug Store News.

The company said in its first-quarter earnings call this year that Flonase accounted for about half of the consumer division’s sales growth.

GlaxoSmithKline started promoting the nasal spray in January, a month before it arrived in stores and six months after the medication received the FDA’s approval as an OTC product.

An earlier lawsuit in which competitor Johnson & Johnson’s McNeil Consumer Healthcare unit asked a court to halt GSK’s Flonase advertisements provided a glimpse at how contentious this category can be. McNeil makes Zyrtec, another leading OTC allergy medication. Redacted legal documents hid how much money GSK spent to launch Flonase, but the lawsuit showed McNeil has spent around $1 billion marketing Zyrtec since 2008. The companies settled the dispute in April.