Synephrine Research

The Safety and Efficacy of Citrus aurantium (Bitter Orange) Extracts and p-Synephrine: A Systematic Review and Meta-Analysis.

Koncz D, Tóth B, Bahar MA, Roza O, Csupor D · Nutrients (2022)

Effect of p-Synephrine on Fat Oxidation Rate during Exercise of Increasing Intensity in Healthy Active Women.

Gutiérrez-Hellín J, Aguilar-Navarro M, Ruiz-Moreno C, Muñoz A, Amaro-Gahete FJ, Posada-Ayala M · Nutrients (2022)

Dose-Response Effects of p-Synephrine on Fat Oxidation Rate During Exercise of Increasing Intensity.

Gutiérrez-Hellín J, Del Coso J · Phytother Res (2018)

Cardiovascular Safety of Oral p-Synephrine (Bitter Orange) in Healthy Subjects: A Randomized Placebo-Controlled Cross-over Clinical Trial.

Shara M, Stohs SJ, Mukattash TL · Phytother Res (2016)

Acute p-synephrine ingestion increases fat oxidation rate during exercise.

Gutiérrez-Hellín J, Del Coso J · Br J Clin Pharmacol (2016)

Acute consumption of p-synephrine does not enhance performance in sprint athletes.

Gutiérrez-Hellín J, Salinero JJ, Abían-Vicen J, Areces F, Lara B, Gallo C · Appl Physiol Nutr Metab (2016)

p-Synephrine, the main protoalkaloid of Citrus aurantium, raises fat oxidation during exercise in elite cyclists.

Gutiérrez-Hellín J, Baltazar-Martins G, Rodríguez I, Lara B, Ruiz-Moreno C, Aguilar-Navarro M · Eur J Sport Sci (2021)

Effects of p-synephrine alone and in combination with selected bioflavonoids on resting metabolism, blood pressure, heart rate and self-reported mood changes.

Stohs SJ, Preuss HG, Keith SC, Keith PL, Miller H, Kaats GR · Int J Med Sci (2011)

Acute p-synephrine ingestion increases whole-body fat oxidation during 1-h of cycling at Fatmax.

Gutiérrez-Hellín J, Ruiz-Moreno C, Del Coso J · Eur J Nutr (2020)

Does the Time of Day Play a Role in the Acute Effect of p-Synephrine on Fat Oxidation Rate during Exercise in Women? A Randomized, Crossover and Double-Blind Study.

Gutiérrez-Hellín J, Del Coso J, Aguilar-Navarro M, Varillas-Delgado D, Ruiz-Moreno C, López-Samanés Á · Nutrients (2022)

p-Synephrine: an overview of physicochemical properties, toxicity, biological and pharmacological activity

In plain English: See also the graphical abstract(Fig. 1).

Kulawik M, Bajewska K, Kulawik A. · EXCLI journal (2025)

Safety and efficacy of citrus aurantium for weight loss.

In plain English: An extensive search of MEDLINE, EMBASE, BIOSIS, and the Cochrane Collaboration Database identified only 1 eligible randomized placebo controlled trial, which followed 20 patients for 6 weeks, demonstrated no statistically significant benefit for weight loss, and provided limited information about the safety of the herb.

Bent S et al. · The American journal of cardiology (2004)

An evidence-based systematic review of bitter orange (Citrus aurantium) by the Natural Standard Research Collaboration.

In plain English: An evidence-based systematic review of bitter orange summarized modest thermogenic effects and a generally tolerable profile at low p-synephrine doses.

Ulbricht C et al. · Journal of dietary supplements (2013)

Review of Published Bitter Orange Extract and p-Synephrine Adverse Event Clinical Study Case Reports.

In plain English: A review of published adverse-event reports examined bitter orange extract and p-synephrine safety.

Stohs SJ et al. · Journal of dietary supplements (2020)

Effects of p-Synephrine and Caffeine Ingestion on Substrate Oxidation during Exercise.

In plain English: Caffeine, p-synephrine, and p-synephrine + caffeine increased the maximal rate of fat oxidation during exercise compared with a placebo, without modifying energy expenditure or heart rate.

Gutiérrez-Hellín J et al. · Medicine and science in sports and exercise (2018)

Citrus Aurantium and caffeine complex versus placebo on biomarkers of metabolism: a double blind crossover design.

In plain English: The findings of this study suggested that normal recommended dosages of 100 mg CA + 100 mg C is sufficient to promote glucose sparing at rest, with modest increases in SNS activity; however, the individual role of CA or C in this response cannot be determined.

Kliszczewicz B et al. · Journal of the International Society of Sports Nutrition (2019)

The safety of Citrus aurantium (bitter orange) and its primary protoalkaloid p-synephrine.

In plain English: A safety review of Citrus aurantium and its primary protoalkaloid p-synephrine summarized cardiovascular considerations.

Stohs SJ et al. · Phytotherapy research : PTR (2011)

Citrus aurantium and synephrine alkaloids in the treatment of overweight and obesity: an update.

In plain English: While some evidence is promising, we conclude that larger and more rigorous clinical trials are necessary to draw adequate conclusions regarding the safety and efficacy of C. aurantium and synephrine alkaloids for promoting weight loss.

Haaz S et al. · Obesity reviews : an official journal of the International Association for the Study of Obesity (2006)