A lot of supplements seem to have synephrine listed on the Supplement Facts panel, and I’ve heard it compared to ephedra. What is it?
Many dietary supplements contain Citrus aurantium, the botanical also known as Bitter Orange, which is a source of synephrine. Synephrine is a stimulant that occurs naturally but that can also be created in a lab, and many safety concerns have been expressed regarding synephrine. The “Editor’s Comments” section of the synephrine entry in the Natural Medicines Comprehensive Database states: “Bitter orange (synephrine) is considered a banned substance by the National Collegiate Athletic Association (NCAA). Bitter orange is frequently used in "ephedra-free" products since FDA banned ephedra in 2004 for serious adverse cardiovascular effects. Bitter orange and caffeine, a frequent combination in weight loss and bodybuilding products, can cause hypertension and increased heart rate in otherwise healthy normotensive adults. No evidence suggests that bitter orange is any safer than ephedra.” For more information on synephrine and ephedra, read the monographs in HPRC’s Dietary Supplement Classification System series. If a product label lists Bitter Orange or Citrus aurantium as an ingredient, there is no way to determine how much synephrine the supplement contains without laboratory testing.