Quite a bit of confusion seems to exist about the difference between Yohimbine and yohimbe. Yohimbine is the principal alkaloid from the herb P. yohimbe. However, there are 31 other yohimbane alkaloids that can be present in herbal yohimbe preparations. Some of these have different and unknown selectivities and potencies (and thus, effects) at the adrenergic receptors (8, 9) -- in addition, these preparations vary greatly from brand to brand and even from batch to batch, as no standardization for extraction exists. In fact, a recent investigation found that most over the counter preparations have little to no actual yohimbine. And, even in the more potent preparations, most people find a higher degree of undesirable effects with the herb vs. pure Yohimbine (due to the afore mentioned 31 other yohimbane alkaloids that can be present).