Chai could be called a spice milk tea, but it is, in essence, black tea prepared with cream or milk and lots of spice. Therefore, its caffeine content matches that of black tea—actually, its caffeine content can surpass black tea, because the base tea is strong.
Traditional chai uses a strong black tea (hot), heavy milk, a sweetener, and various spices (usually cardamom, cinnamon, ginger, cloves, and pepper). Different regions and different people have their own combination of spices. Regular milk can be substituted for heavy milk, if necessary. Variations of serving chai have also developed, such as iced chai, decaffeinated chai, chocolate chai, and chai milkshake.
The combination of spices can serve as a natural digestive aid.