Bitter Orange

Citrus aurantium · p-Synephrine

Snapshot

Indications	Contraindications
Exercise fat oxidation^{1, 2} Resting energy expenditure^{3, 4} Anxiety, inhaled oil^{5, 6} Antenatal depression and anxiety⁷ Pregnancy nausea and vomiting⁸	Pregnancy or breastfeeding⁹ Heart disease or hypertension¹⁰ Monoamine oxidase inhibitor use¹⁰

Bitter orange (Citrus aurantium) extracts are standardized to p-synephrine, which acts on adrenergic pathways¹¹. It is structurally similar to ephedrine but pharmacologically distinct¹². Supplementation is driven by a proposed thermogenic effect, and extracts are taken for weight loss and sports performance⁴; use rose after ephedra left the market¹². The essential oil is inhaled for anxiety and nausea.

A meta-analysis of placebo-controlled trials found no significant weight loss and a rise in blood pressure with prolonged use¹³. In a 2023 review of in vitro and animal models, synephrine showed anti-inflammatory and anti-cancer activity, with no human trial testing it. Products come as capsules, liquids, and powders, and a laboratory analysis of United States supplements found most label synephrine amounts inaccurate and some products adulterated with synthetic amines; see Form comparison.

The cardiovascular caution rests on blood pressure and heart rate effects, and case reports of myocardial infarction involved multi-ingredient products, so causation is unclear¹². Health Canada labels ask for a practitioner's advice before use alongside prescription medications⁹.

Last updated October 16, 2026. Read how we make monographs.

In the full monograph

64 sources, 61 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources