Can buttermilk be left out overnight?

Buttermilk can be safely left out at room temperature for up to 2 hours, but it's best to refrigerate it to maintain its freshness and prevent spoilage. Leaving it out overnight is not recommended, as harmful bacteria can develop, especially in warm environments. If buttermilk has been left out for more than 2 hours, it's advisable to discard it to avoid any health risks.