The bitter orange tree is native to Africa and tropical Asia. It's also grown in the Mediterranean, California, and Florida.
Bitter orange contains synephrine, a stimulant related to ephedrine. It supposedly works by raising the number of calories burned.
After the FDA banned weight loss products containing ephedra, many makers switched to bitter orange. But it’s unclear if bitter orange is safer.
The Natural Medicines Comprehensive Database says that bitter orange is "possibly unsafe" and there is insufficient evidence to rate it for weight loss.
Some studies have shown bitter orange supplements can increase blood pressure and heart rate. There have been reports that bitter orange may have had dangerous side effects in people who took bitter orange alone or in combination with other stimulants such as caffeine. These effects include:
- irregular heartbeat
- heart attack
According to the FDA, bitter orange may not be safe to use as a dietary supplement. You should especially avoid taking bitter orange supplements if you have:
- a heart condition
- high blood pressure
You should also avoid bitter orange supplements if you are taking caffeine, medications (such as MAO inhibitors), or herbs or other supplements that speed up the heart rate.