Synephrine is a stimulant similar to caffeine and ephedrine, being the main active compound of the fruit of a plant called Citrus aurantium. The fruit is also called as zhi shi, green orange, sour orange or bitter orange in other parts of the world.
As synephrine is chemically very similar to the ephedrine and pseudo-ephedrine it is the common substitute for ephedrine in diet pills labeled as "ephedra-free", having similar effects in providing an energy boost, suppressing appetite, increasing metabolic rate and caloric expenditure. In spite of the fact that synephrine is similar to ephedrine, it doesn’t appear to have the same negative central nervous effects and it stimulates fat metabolism without the negative cardiovascular side effects as it stimulates specific adrenergic receptors.
The effects of synephrine alone or in combination with other ingredients fall into the category of acting as a mild stimulant and based on some late studies both isolated synephrine and citrus aurantium extract raise blood pressure in animal studies, so it should be avoided by individuals with cardiovascular concerns such as hypertension.
