Yakult is a probiotic milk drink that contains live bacteria, and like most dairy products, it is best kept refrigerated to maintain its quality and safety. When left at room temperature, the live probiotic bacteria in Yakult can begin to deteriorate, reducing the drink's effectiveness and potentially leading to spoilage.
The specific duration that Yakult can be kept without refrigeration depends on various factors, including the ambient temperature, the initial condition of the drink, and the presence of preservatives. Generally, it is recommended not to leave Yakult unrefrigerated for more than a few hours, especially in warm or hot weather.
If you are traveling or need to take Yakult with you on the go, it's best to use a portable cooler or insulated bag with ice packs to keep the drink cold and maintain the viability of the probiotic bacteria. Always follow the storage recommendations on the product label, and if you are unsure about the safety of the drink after leaving it unrefrigerated for an extended period, it's safer to discard it to avoid any risk of foodborne illness or diminished probiotic benefits.