Final answer:
St. John's wort is an herbal medication for depression that is widely used in Europe and is now being prescribed in the United States. It is believed to work by increasing levels of serotonin, dopamine, and norepinephrine in the brain.
Step-by-step explanation:
In the United States, St. John's wort is now being prescribed as an herbal medication for depression. While it was originally widely used in Europe, its use has gained popularity in the United States as well. St. John's wort is the common name for a plant called Hypericum perforatum, and it is believed to work by increasing levels of serotonin, dopamine, and norepinephrine in the brain.