Orange juice should be safe to drink for up to four hours without refrigeration. After four hours without refrigeration, it is best to discard the juice.
When purchasing juice, make sure that it has been pasteurized or treated to destroy harmful bacteria that are capable of causing serious foodborne illness. Most fruit and vegetable juices sold in supermarkets are pasteurized, and those that are not must have a warning label on the packaging. However, warning labels are not required for juice or cider that is fresh-squeezed and sold by the glass at places such as farm markets or apple orchards. If there is any uncertainty about whether the juice has been treated, be sure to ask.