Synephrine, also commonly referred to as bitter orange, is derived from the fruit of small citrus trees that grow in Eastern Africa and more tropical areas of Asia, but also from imported trees in areas of the United States, such as Florida. Once the orange is broken down into synephrine, it provides similar effects to ephedrine in diet pills, which was replaced -- and in some areas of the world made illegal -- due to potentially serious health effects. Although synephrine has yet to manifest the same problems as ephedrine, there are potential side effects that you should be aware of before using a product containing the ingredient.
One of the most noticeable side effects of synephrine is an increased heart rate. Synephrine contains chemicals that act as stimulants to your body. This stimulation increases your heart rate, sometimes to even dangerous levels. This danger increases if you pair the synephrine-containing product with other stimulants such as caffeine in other diet supplements or even soda or energy drinks.
As synephrine increases your heart rate, the higher heart rate increases your blood pressure. If you regularly use synephrine, this increased heart rate can raise your risk for serious health problems, says the Mayo Clinic. For example, the excess blood pressure can weaken the blood vessels resulting in bulging aneurysm. It may also cause the heart to work too hard resulting in the heart muscle thickening, affecting its ability to pump properly.
Your risks for fainting are also increased while taking products with synephrine, according to the National Center for Complementary and Alternative Medicine. Fainting can occur in relation to the change in blood pressure associated with the ingredient or in response to decreased blood flow to the heart due to hardening and thickening of the arteries.
Your risks for having an ischemic stroke are also increased when using products containing synephrine, according to studies performed by doctors and pharmacists at the Mayo Clinic. The vasoconstricting properties of synephrine narrow the blood vessels leading to the brain, which can result in the development of an ischemic stroke.
With the stimulant effects of synephrine also comes an increased risk for heart attack, even in individuals who are otherwise healthy, states the Mayo Clinic. Heart attack can result from hardening and thickening the arteries. This reduces the amount of blood and oxygen that can reach the heart muscle, resulting in angina of the muscles or complete death of the muscle, as seen in a heart attack.