Yohimbe bark extract

The terms yohimbine , yohimbine hydrochloride , and yohimbe bark extract are related but not interchangeable. Yohimbine is an active chemical (indole alkaloid) found in the bark of the Pausinystalia yohimbe tree. Yohimbine hydrochloride is a standardized form of yohimbine that is available as a prescription drug in the United States, and has been shown in human studies to be effective in the treatment of male impotence. Yohimbine hydrochloride has also been used for the treatment of sexual side effects caused by some antidepressants (SSRIs), female hyposexual disorder, as a blood pressure boosting agent in autonomic failure, xerostomia, and as a probe for noradrenergic activity.

Synonyms

Aphrodien, Corynanthe johimbi, Corynanthe yohimbi , corynine, johimbi, Pausinystalia johimbe, Pausinystalia yohimbe , quebrachine, Rubiaceae (family), yohimbehe, yohimbehe cortex, yohimbeherinde, yohimbene, yohimbime, yohimbine.

Evidence

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Uses based on scientific evidence	Grade^*
Dry mouth (xerostomia) Studies report that yohimbine is able to increase saliva in animals and in humans. Based on these few studies, yohimbine has been used for the treatment of dry mouth caused by medications, such as antidepressants. However, yohimbe bark extract may not contain significant amounts of yohimbine, and therefore may not have these effects. More research is needed before a recommendation can be made.	C
Erectile dysfunction (male impotence) Yohimbine hydrochloride is a prescription drug that has been shown in multiple human trials to effectively treat male impotence. Although yohimbine is present in yohimbe bark extract, levels are variable and often very low. Therefore, although yohimbe bark has been used traditionally to reduce male erectile dysfunction, there is not enough scientific evidence to form a firm conclusion in this area.	C
Inhibition of platelet aggregation Pre-clinical studies report that yohimbine alkaloid, isolated from yohimbe bark, may inhibit platelet aggregation. Research in humans is limited, and more research is necessary in this area.	C
Libido (women) Yohimbine has been proposed to increase female libido (sexual interest). There is only limited poor-quality research in this area, and more study is needed before a recommendation can be made.	C
Nervous system dysfunction (autonomic failure) It is theorized that yohimbine may improve orthostatic hypotension (lowering of blood pressure with standing) or other symptoms of autonomic nervous system dysfunction. However, yohimbe bark extract may not contain significant amounts of yohimbine, and therefore may not have these proposed effects. More research is needed before a recommendation can be made.	C
Sexual side effects of selective serotonin reuptake inhibitor (SSRI) antidepressants Yohimbine hydrochloride, a standardized form of yohimbine that is available as a prescription drug in the United States, has been suggested to treat sexual dysfunction due to SSRI antidepressants. However, research in this area is limited, and more study is needed before a recommendation can be made. In addition, yohimbe bark extract may not contain significant amounts of yohimbine, and therefore may not have these proposed effects.	C

*Key to grades
A: Strong scientific evidence for this use;
B: Good scientific evidence for this use;
C: Unclear scientific evidence for this use;
D: Fair scientific evidence against this use;
F: Strong scientific evidence against this use.

Grading rationale

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Alzheimer's disease, anesthetic, angina, aphrodisiac, atherosclerosis, clonidine overdose, cognition, coronary artery disease, cough, depression, diabetic complications, diabetic neuropathy, exhaustion, feebleness, fevers, hallucinogenic, high cholesterol, insomnia, leprosy, low blood pressure, narcolepsy, obesity, panic disorder, Parkinson's disease, postural hypotension, pupil dilator, schizophrenia, syncope.

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Adults (18 years and older)

The following doses are based on human trials of pharmaceutical standardized yohimbine hydrochloride (available by prescription in the United States). No reliable clinical studies are available for administration of yohimbe bark extract. For erectile dysfunction (male impotence), 15 to 42 milligrams of yohimbine hydrochloride daily in three divided doses (for example, 5.4 to 10 milligrams three times daily) has been studied. For libido in women, 5.4 milligrams three times daily of yohimbine hydrochloride has been studied. For sexual side effects caused by antidepressant drugs, 2.7 to 16.2 milligrams of yohimbine hydrochloride has been studied. For autonomic dysfunction/orthostatic hypotension, 5.4 to 12 milligrams of daily yohimbine has been studied. For dry mouth (xerostomia), 6 milligrams three times daily of yohimbine hydrochloride has been studied.

Children (younger than 18 years)

Yohimbe and yohimbine hydrochloride are not recommended for use in children.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

In theory, allergy/hypersensitivity to yohimbe, any of its constituents, or yohimbine-containing products may occur.

Side Effects and Warnings

Yohimbe bark extract is traditionally said to cause occasional skin flushing, piloeretion (body hair standing up), painful urination, genital pain, reduced appetite, agitation, dizziness, headache, irritability, nervousness, tremors, or insomnia.

Multiple adverse effects have been associated with the use of the drug yohimbine hydrochloride, although in recommended doses, it is usually tolerated. If adverse effects occur, discontinuing the drug will likely stop the effects. In theory, these same side effects may also occur with the use of yohimbe bark extract, which contains variable (usually low) amounts of yohimbine.

There are reports of rash, flushing, breathing difficulty, cough, runny nose, nausea, vomiting, increased salivation, diarrhea, increased frequency of urination, kidney failure, muscle aches, and a lupus-like syndrome with the use of yohimbine hydrochloride. Yohimbine has also been associated with tremulousness, insomnia, anxiety, irritability, and excitability. Yohimbine may precipitate panic attacks, anxiety, manic episodes or psychosis in patients with a history of mental illness.

In animal research, yohimbine has been associated with increased motor activity and seizures at higher doses. In humans, yohimbine may change the seizure threshold (the likelihood that a seizure will happen in some people), and may cause blood pressure/heart rate increases, fluid retention, chest discomfort and heart rhythm abnormalities. Higher doses may lower blood pressure. Yohimbine can enter the brain through the bloodstream. Yohimbine may increase the risk of bleeding by altering platelet function, and may dangerously reduce the number of white blood cells (agranulocytosis).

Symptoms of toxicity from yohimbine can include paralysis, dangerously low blood pressure, heart rhythm abnormalities, heart failure, and death. These same risks theoretically may also exist with yohimbe bark extract, depending on the concentration of yohimbine present and the amount ingested. Beta-blocker drugs such as metoprolol (Lopressor®, Toprol®) may be protective against yohimbine toxicity.

Pregnancy and Breastfeeding

Yohimbe should be avoided during pregnancy because it may relax the uterus and may be toxic to the fetus. Yohimbe should be avoided during breastfeeding, due to reports of deaths in children.

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.

Interactions with Drugs

Multiple drug interactions may occur with the use of yohimbine hydrochloride. In theory, these effects may also apply to yohimbe bark extract, which contains variable (usually low) amounts of yohimbine.

Based on human study, yohimbine has been reported to block the effects of alpha-adrenergic drugs. Yohimbine may increase the effects of drugs that are anti-adrenergic, such as clonidine or guanabenz. Use of yohimbine with central nervous system stimulants may have additive effects. In theory, due to inhibition of monoamine oxidase (MAOI activity), use of yohimbine with drugs like isocarboxazid (Marplan®), phenelzine (Nardil®), tranylcypromine (Parnate®) or linezolid (Zyvox®) may produce additive side effects, such as an increased risk of extremely high blood pressure.

Based on human study, use of ethanol (alcohol) with yohimbine may produce an additive effect of increasing intoxication. Based on human study, yohimbine may increase pain relief from morphine and may increase or decrease withdrawal symptoms caused by the medication naloxone. According to historical use and animal study, yohimbine may increase the effects of diabetic medications, including insulin, although there is no reliable scientific evidence in this area. Caution is advised when using medications that may lower blood sugar. Patients taking drugs for diabetes by mouth or insulin should be monitored closely by a qualified healthcare provider. Medication adjustments may be necessary.

Based on human study, use of yohimbine with physostigmine in patients with Alzheimer's disease may be associated with anxiety, agitation, restlessness, and chest pain. Use of yohimbine with antihistamines is cautioned, although there is no reliable scientific evidence in this area. The combination of yohimbine with anti-muscarinic agents may result in increased risk of toxicity. In theory, yohimbine may add to the effects of drugs that lower blood pressure.

In theory, yohimbine may interfere with the way the body processes certain drugs using the liver's "cytochrome P450" enzyme system. As a result, the levels of these drugs (and yohimbine) in the blood may be altered, and may cause increased or decreased effects or potentially serious adverse reactions. Patients using any medications should check the package insert and speak with a qualified healthcare professional or pharmacist about possible interactions.

Yohimbine may also interact with benzodiazepines (tranquilizers), antibiotics such as linezolid, phenothiazines and tricyclic antidepressants (TCAs). Patients using any medications should check the package insert and speak with a qualified healthcare professional or pharmacist about possible interactions.

Interactions with Herbs and Dietary Supplements

Multiple interactions may occur between the drug yohimbine hydrochloride and herbs/supplements. In theory, these effects may also apply to yohimbe bark extract, which contains variable (usually low) amounts of yohimbine.

In theory, other over-the-counter products containing stimulants, including caffeine, phenylephrine and phenylpropanolamine (removed from the U.S. market), may lead to additive effects when used in combination with yohimbine. Yohimbine theoretically may interfere with blood pressure control and should be used cautiously with other herbs or supplements that affect blood pressure.

Due to inhibition of monoamine oxidase, use of yohimbine with herbs/supplements with possible similar properties may produce additive effects, such as an increased risk of dangerously high blood pressure (hypertensive crisis). In theory, caffeine-containing agents such as coffee, tea, cola, guarana, and mate may also increase the risk of hypertensive crisis when taken with yohimbine.

Yohimbine theoretically may add to the effects of herbs or supplements that may lower blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.

In theory, yohimbine may interfere with the way the body processes herbs or supplements using the liver's "cytochrome P450" enzyme system. As a result, the levels of herbs or supplements (and yohimbine) in the blood may be altered, and may cause increased or decreased effects or potentially serious adverse reactions. It may also alter the effects that other herbs or supplements possibly have on the P450 system.