Grapefruit juice is the juice from grapefruits. It is rich in vitamin C and ranges from sweet-tart to very sour. Variations include white grapefruit, pink grapefruit and ruby red grapefruit juice.
Grapefruit juice is important in medicine because of its interactions with many common drugs including caffeine and medications, which can alter how they behave in the body.
Grapefruit juice is a common breakfast beverage in the United States.