Bitter orange
Bitter orange, Citrus aurantium, is a sour citrus fruit whose peel contains the alkaloid synephrine.
Also listed as P-synephrine, Citrus Aurantium, Synephrine, Citrus aurantium
What it is studied for
The strongest rated effects first. Bars show the size of the effect, the letter grades the evidence, and each rating lists the studies behind it.
Is bitter orange a useful weight-loss supplement?
Bitter orange, Citrus aurantium, is the sour citrus fruit also called Seville orange. It contains p-synephrine, a compound used in supplements marketed for weight loss and sports performance. That marketing goes beyond what the human trials establish. 1 2
A stimulant claim is not a weight-loss result
Synephrine can act on the cardiovascular system. Its chemical resemblance to ephedrine does not mean the two substances behave identically; a proposed metabolic effect still needs to translate into worthwhile weight loss in people. 1 2 3
Why people take it
SuppCo community snapshot, 2026-09-28. Reasons for use are not evidence that it works.
Questions people ask
Is it the same as ephedra?
No. Bitter orange contains p-synephrine, which has different pharmacologic properties from ephedrine. That distinction does not establish supplement safety. 1
Does it burn enough fat to cause weight loss?
The pooled clinical evidence did not show a significant weight-loss benefit. A metabolic explanation alone cannot substitute for that outcome. 2
Is 6.7 mg a recommended weight-loss dose?
No. This figure comes from BfR’s risk assessment of supplemental synephrine exposure, not a successful weight-loss regimen. 3
Are serious heart problems definitely caused by bitter orange?
The reports are concerning, but most involve combinations of ingredients. They cannot isolate bitter orange as the cause. 1