Yohimbine, Bark to Pharmacology
Yohimbine, the principal alkaloid of Pausinystalia johimbe
Evidence grade 2 of 5, Thin. Read how the Atlas grades evidence.
The written rationale for this grade is still being prepared.
- FDA
- Prescription yohimbine HCl historically approved; yohimbe bark supplements are unapproved and carry safety concerns
Reference only. Not medical advice.
What can go wrong
Yohimbine can cause anxiety, agitation, tachycardia, hypertension, tremor, insomnia, nausea, and, in case reports, hypertensive crisis, arrhythmia, and demand-related myocardial injury. Risk is amplified in people with cardiovascular disease, hypertension, anxiety disorders, or kidney/liver impairment, and with monoamine oxidase inhibitors, stimulants, or other sympathomimetics. Crude yohimbe-bark supplements are particularly hazardous: analyses have found alkaloid content ranging from negligible to many times the labeled amount, so a 'standard' capsule can deliver an unpredictable, potentially toxic dose. Poison-center advisories have flagged yohimbine as a potentially fatal over-the-counter ingredient.
This is something to take to a clinician. The Atlas can tell you what is known about yohimbine, bark to pharmacology in general. It cannot tell you what is happening in your body, and the difference matters most for exactly the symptoms that bring people to this page.
Yohimbine is the principal indole alkaloid of the West African yohimbe tree (Pausinystalia johimbe), used in Central/West African ethnomedicine and later isolated as a defined pharmaceutical. It is a relatively selective alpha-2 adrenergic receptor antagonist: by blocking the presynaptic 'brake' on norepinephrine release it raises sympathetic tone, an effect with a plausible but inconsistent benefit for erectile function. Prescription yohimbine HCl was used for erectile dysfunction before PDE5 inhibitors; crude yohimbe-bark supplements deliver wildly variable, sometimes dangerous, alkaloid doses. This entry treats the pharmacology and risk in depth, complementing the broader African-traditions overview.
A West African bark that became a real drug, and a real cardiovascular hazard.
What people take it for
These are the reasons people give for taking it. They are not effects it has been shown to have.
How it is supposed to work
Yohimbine selectively antagonizes alpha-2 adrenergic receptors. Presynaptic alpha-2 receptors normally inhibit further norepinephrine release; blocking them increases sympathetic outflow and circulating noradrenergic activity. In the penis, alpha-2 blockade may favor the relaxation/engorgement balance, the proposed basis for a pro-erectile effect. At higher concentrations yohimbine also interacts with alpha-1, serotonergic, and dopaminergic systems, which contributes to its anxiety-provoking and cardiovascular effects.
Yohimbine is a monoterpenoid indole alkaloid structurally related to reserpine and the corynanthe alkaloids. Yohimbe bark contains a mixture of related alkaloids (corynanthine, rauwolscine/alpha-yohimbine and others), which differ in receptor selectivity, a key reason crude bark behaves unpredictably.
The benefit and the hazard share one mechanism
The headline mechanism, raising sympathetic tone, is also the source of the danger. The same noradrenergic surge that might aid an erection can raise blood pressure and heart rate, trigger anxiety and panic, and in case reports cause hypertensive episodes and type II (demand) myocardial injury. Crude yohimbe supplements compound this because alkaloid content per dose is poorly controlled and often undeclared.
Safety in detail
- Cardiovascular: hypertension, tachycardia, arrhythmia, reported type II myocardial injury.
- Neuropsychiatric: anxiety, panic, agitation, insomnia.
- Drug interactions: MAOIs, stimulants, other sympathomimetics, some antidepressants.
- Supplement variability: labeled vs actual alkaloid content is frequently inaccurate; bark products may be far more or less potent than stated.
What people get wrong
Often saidYohimbe and yohimbine are the same thing.
ActuallyYohimbine HCl is a defined, dosed pharmaceutical alkaloid; 'yohimbe' bark/extract supplements contain a variable alkaloid mixture at uncontrolled doses and behave far less predictably.
Often saidIt is a gentle natural libido booster.
ActuallyIt is a sympathomimetic with documented cardiovascular and psychiatric risks; poison centers have issued warnings about it.
Often saidIt still has a clear place in ED treatment.
ActuallySince selective PDE5 inhibitors arrived, yohimbine's modest and inconsistent benefit and its risk profile have relegated it to a minor, largely historical role.
Who profits, and who pushes back
Nobody is named here yet, because we have not done that work on this entry. Read that as unfinished. Somebody almost certainly sells this, and somebody almost certainly disputes it. Assume both until we have checked.
Where the research comes from
| Place | Share of published research |
|---|---|
| West/Central Africa (origin) | 40% |
| Europe (isolation/pharmacology) | 30% |
| North America (supplement market/case reports) | 30% |
How we got here
Pausinystalia johimbe bark was used in Central and West Africa (notably the Cameroon/Congo region) as a stimulant and reputed aphrodisiac. European chemists isolated and named yohimbine around the turn of the 20th century, and yohimbine HCl entered Western pharmacology as one of the few specifically pro-erectile drugs available for much of the 20th century. It was prescribed for impotence in the decades before sildenafil. The 1998 arrival of PDE5 inhibitors, combined with growing recognition of yohimbine's cardiovascular and neuropsychiatric risks and the unreliability of crude bark products, pushed it to the margins of legitimate practice even as it persisted in the supplement and bodybuilding markets.
- Pre-colonialEthnomedicinal use of yohimbe bark in Central/West Africa
- ~1896Yohimbine isolated and characterized by European chemists
- 20th c.Prescription yohimbine HCl used for erectile dysfunction
- 1998PDE5 inhibitors arrive; yohimbine's role contracts sharply
- 2016Supplement analyses document large alkaloid-content variability
- 2020sPoison-center advisories flag yohimbine as a hazardous OTC ingredient
The people taking it
Yohimbine persists globally as a supplement marketed for libido and fat loss, and as a niche pharmacologic agent. The source tree is harvested in Cameroon and neighboring countries, raising the same benefit-sharing and sustainable-harvest questions as other West African medicinal barks.
What we do not know
- Can standardized yohimbine HCl carve out any modern niche given PDE5 inhibitors?
- How can supplement alkaloid content be reliably regulated to reduce cardiovascular harm?
The market for this
What follows describes how this is bought and sold. It is not a buying guide and it is not an endorsement of any seller.
Yohimbe bark is harvested largely from wild trees in Cameroon and neighboring countries. Sustainable-harvest pressure and limited benefit-sharing for source communities mirror the sovereignty concerns seen with other commercialized ethnobotanicals.
At a glance
- Drug class
- Alpha-2 adrenoceptor antagonist (indole alkaloid)
- Botanical source
- Pausinystalia johimbe bark
- Half-life
- Short, roughly 0.5-2 hours (variable)
- Pre-Viagra status
- Prescription yohimbine HCl used for ED
What this entry does not yet cover
What follows is unfinished work on our side, not a finding about Yohimbine, Bark to Pharmacology. A short entry is not a safe entry.
- Cost and market. We have not documented what it sells for or who sells it.
- Supply chain. We have not mapped where it is made.
- Who uses it. We have not documented the user groups.
- What could change. No forward-looking summary yet.
- How it compares. We have not set it against the alternatives.
- Children and teenagers. We have not checked what is known about younger people.
Sources
The studies below are named and described, but not linked. You cannot open them from here and check our reading against them, which means this page is our summary of the literature rather than a document you can verify. Weigh it accordingly until the links exist.
The studies that matter
Meta-analysis of yohimbine for erectile dysfunction (Ernst & Pittler, J Urol)1998
Pooled trials suggested yohimbine was superior to placebo for ED with relatively benign serious-adverse-event rates, but trials were small and heterogeneous
Detection of yohimbine content variability in supplements (Cohen et al.)2016
Analysis of yohimbe-labeled supplements found highly inconsistent and often inaccurate alkaloid quantities, including products with far more than labeled