Going viral on TikTok is turning into a supply-chain puzzle for retailers, reports The Wall Street Journal. Brands from Dash miniature waffle makers to Stanley water tumblers are struggling to keep up with demand once one of their items takes off on social media and quickly sells out. 

The key challenge for brands is figuring out how to reorganize supply chains to suit a sleeper hit. So-called social commerce shopping grew 37% last year to $37 billion and is expected to hit $80 billion by 2025, according to McKinsey & Co. The growth is being fueled by content creators posting videos of their favorite products and is particularly popular among Gen Zers who can click links to buy coveted items right in an app.

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Makeup company Charlotte Tilbury says it is adding capacity into its supply chain to cope with sudden demand swings. And supply-chain company Trendsi  is helping retailers fill orders more quickly by drop-shipping items direct from manufacturers to shoppers’ homes.