Writing in the journal Neurology International, researchers from the University of Alabama at Birmingham reviewed the physiological and psychological outcomes—along with the sometimes-serious side effects—of yohimbine supplementation in the context of endurance and anaerobic exercise.
“Yohimbine (YHM) is a naturally occurring alkaloid that induces increases in sympathetic nervous system (SNS) activation effectively initiating ‘fight or flight’ responses,” they wrote. “In supplement form, YHM is commonly sold as an isolated product or combined into multi-ingredient exercise supplements and is widely consumed in fitness settings despite the lack of empirical support until recently.”
According to data from market research firm SPINS for the 52 weeks ending Dec. 29, 2024, sales of yohimbe (the bark extract from which the yohimbine alkaloid is derived) in condition specific supplements was close to $19.5 million, down 30% from a year prior across U.S. multi outlet and natural retail channels. Top categories include reproductive supplements ($13.9 million, down 10.1%) and energy supplements ($5.6 million, down 54.9%).
Due to inconsistencies in the concentrations of yohimbine found in the bark, it is commonly consumed in its commercially available and more soluble form of yohimbine hydrochloride as a prescription drug.
Yohimbine in exercise
Traditionally, yohimbine has been used in African folk and Western medicine to increase energy and vitality in the context of erectile dysfunction and athletic performance, as well as for weight loss, high blood pressure and heart problems. In multi-ingredient products, it is often incorporated as a stimulant additive.
The University of Alabama researchers noted that much of the science to date—which has investigated yohimbine and cardiovascular function, blood flow, lactate metabolism and muscle function—has been carried out in animal models. In the domain of performance enhancement, it works by increasing sympathetic activation, hemodynamic adaptation, boosting alertness and decreasing fatigue.
More recently, studies in humans have explored the effects of yohimbine supplementation on aerobic (e.g., cycling, rowing) and anaerobic (e.g., repeated sprints, bench press) exercise performance. The current review focused on those studies that used the isolated compound rather than multi-ingredient formulations to distinguish effects.
“YHM has been implicated in improved exercise performance both in aerobic and anaerobic modalities,” the researchers wrote. “Physiologically, YHM has been shown to increase catecholamines, oxygen consumption, muscular force/power, markers of ATP breakdown, heart rate and lower lactate levels in response to exercise. The psychological effects of YHM have also been characterized during exercise, revealing increases in motivation, feelings of energy and alertness/arousal.”
As a sympathomimetic (a compound that mimics responses due to stimulation of sympathetic nerves), they explained that yohimbine primarily acts as an α2-adrenergic receptor antagonist effectively increasing norepinephrine release from sympathetic neurons. It is this spillover phenomenon that is then linked to the potential to enhance neuromuscular control and alter fuel utilization for exercise performance.
Addressing the disparities in some of the performance enhancement findings across the studies reviewed, the researchers suggested that differences in supplement regimen and time course as contributing factors.
“Chronic consumption of YHM likely results in desensitization and habituation that may not be experienced with acute dosing regimens,” they wrote. “Thus, it is plausible that the ergogenic effects of YHM are transient in nature with optimal benefits being realized through acute supplementation only. Higher and more frequent dosages may accelerate this process, but further research using varying dosages with serial timepoint performance measurements is needed to be conclusive.”
Safety and usage considerations
The review cautioned that yohimbine use “is not without risk as it has high interindividual variability in bioavailability, can be deceptively potent, lacks widely accepted dosing recommendations and, when taken in large doses, has been empirically documented to result in serious side effects.”
These range from anxiety, nervousness, insomnia, increased heart rate, elevated blood and gastrointestinal issues to cardiac arrhythmias, myocardial infarction, seizures and renal failure in more extreme cases. Yohimbine can also interact with medications like antidepressants, antihypertensives and stimulants.
While the evidence presented suggested that low doses of 2.5 mg to 5 mg are tolerable and “may serve as an ideal exercise training aid due to acute enhancement of physical performance”, the review noted that safety concerns remain outstanding, and temperance should be used when using yohimbine and similar sympathomimetics.
“A challenge in making recommendations supporting the use of YHM currently is the lack of regulation and oversight of purity, form, contamination, etc.,” the researchers wrote. “It is also not well known how YHM may influence the action of other supplements in multi-ingredient formulas that are commonly sold commercially.”
As such, they called for investigations in larger sample sizes and further research into dose–response, multi-ingredient supplements and the effects of chronic use before making widespread recommendations to athletes and recreational exercisers about safe yohimbine supplementation.
Source: Neurology International. doi: 10.3390/neurolint16060131. “Ergogenic and Sympathomimetic Effects of Yohimbine: A Review”. Authors: Sophia Porrill, Rebecca Rogers and Christopher Ballmann.