A slew of Zyn competitors are rushing in to capitalize on troubles at the Philip Morris-owned brand, which is facing a run on supply for its oral nicotine pouches and a subpoena that prompted a halt in its online sales in the U.S. “With Zyn’s falling-out right now, and manufacturing issues, we want to strike while the iron is hot,” Song Jo, a sales manager for California-based wholesaler Apex Distribution, said at the Alternative Products Expo trade show last month in Houston, where he was displaying oral nicotine pouches branded to former professional basketball player Dennis Rodman.

These imitators are the latest competitive threat to big tobacco companies like Philip Morris International Inc. in the US. Tobacco companies are focusing on the small but growing category of oral pouches to make up for declining cigarette sales and difficulties competing in the vape market.

They also pose a challenge for US regulators, who will have to contend with another wave of unauthorized nicotine products after an explosion in demand for unauthorized flavored vapes since last year. Oral nicotine pouches were a $6 billion market in the US last year and are expected to reach $18 billion by 2027, according to market research firm Euromonitor International. Zyn’s sales volume jumped 80% in the first quarter, according to the company.

Putting further pressure on supply, Philip Morris also decided to halt online sales nationwide in June after receiving a subpoena in the District of Colu.