Yohimbine (tablets)

Yohimbine is an alkaloid from the bark of the West African yohimbe tree (Pausinystalia johimbe). As yohimbine hydrochloride it has been a medicine for decades, mostly for erectile dysfunction in the past. Since sildenafil and its relatives arrived it plays little role there.

In fitness and research circles yohimbine is known for a different reason: it blocks the alpha-2 receptors that hold back fat release in stubborn fat stores. That is why it shows up in cutting phases alongside training and a calorie deficit. At the same time it drives the sympathetic nervous system, exactly the system that pushes up heart rate, blood pressure and nervousness.

Bark extracts in supplements often contain uncertain amounts, while the tablet holds a defined dose of yohimbine hydrochloride. The range offers yohimbine as a 10mg tablet, 100 per tub.

This information is for research and educational purposes only. No medical advice.

Alpha-2 receptors sit in two important places. On sympathetic nerve endings they act as a brake: once enough noradrenaline has been released they throttle further release. Yohimbine takes off that brake and noradrenaline rises. Hedner and colleagues (1992) saw plasma levels triple within 15 minutes of an injection.

The second place is the fat cell. There alpha-2 receptors inhibit lipolysis while beta receptors drive it. Stores such as the belly, hips or thighs carry many alpha-2 receptors and give up fat reluctantly. Yohimbine tips the balance towards release. Galitzky (1988) showed that oral yohimbine raises glycerol and free fatty acids in fasted men, even more so during exercise.

The catch: after a meal the effect was gone completely. Insulin suppresses lipolysis more strongly than yohimbine can release it. That is why yohimbine is taken fasted, usually in the morning or before cardio. The half-life is short and absorption from the gut varies widely between people. The same tablet can act very differently in two people.

Galitzky and colleagues (Eur J Clin Invest 1988) first showed in isolated human fat cells that yohimbine is the most potent of several alpha-2 blockers on lipolysis. Healthy men then took 0.2mg per kg orally. Free fatty acids and glycerol rose in the fasted state and noradrenaline went up by 40 to 50 percent. After a meal the effect vanished entirely. Pulse and blood pressure stayed largely stable in this short experiment.

Hedner and colleagues (Eur J Clin Pharmacol 1992) studied the pharmacokinetics in 13 young men after an injection. Half-life ranged from 0.25 to 2.5 hours and almost all of the drug is cleared by the liver. Plasma noradrenaline tripled within 15 minutes while adrenaline stayed the same.

Ostojic (Res Sports Med 2006) gave 20 professional footballers 20mg a day in two doses or placebo for three weeks. Body fat fell from 9.3 to 7.1 percent in the yohimbine group while body mass, muscle mass and all performance tests were unchanged. Nobody reported side effects, though the group was small and young.

The meta-analysis by Ernst and Pittler (J Urol 1998) pooled seven randomised trials on erectile dysfunction. Yohimbine did clearly better than placebo and serious adverse events were rare and reversible. The review by Cimolai (J Diet Suppl 2011) takes a sober view of the fitness side: no clear evidence for better performance or more muscle, but dose-dependent toxicity with agitation, anxiety, hypertension and tachycardia.

• Rising blood pressure: the key side effect. More noradrenaline pushes pressure up, clearly so in some people. Anyone with elevated readings already should not use it.
• Racing heart and palpitations: resting pulse rises and extra beats are possible. Stronger together with caffeine, ephedrine or other stimulants.
• Anxiety and panic: research uses yohimbine deliberately to provoke anxiety responses. People with panic or anxiety disorders are especially sensitive.
• Restlessness, tremor, sweating: typical signs of too high a dose, often with chills or goosebumps.
• Sleep problems: mainly when taken after midday.
• Frequent urination, nausea, headache: reported occasionally.
• Interactions: MAO inhibitors and tricyclic antidepressants amplify the effect dangerously. Clonidine and other blood pressure drugs are weakened.
• Not suitable with: high blood pressure, heart disease, anxiety or panic disorder, bipolar disorder or liver or kidney disease.

Keep the tablets dry at room temperature in the closed tub and away from light. Not in the bathroom or kitchen, as moisture damages tablets. Keep out of reach of children, as even a few tablets can be dangerous for a child.