While yohimbine behaves as an aphrodisiac in some mammals, it does not do so in humans. It has been prescribed as a treatment for erectile dysfunction, but its reported clinical benefits were modest and it has largely been superseded by the PDE5 inhibitor class of drugs. Substances that have purported to be extracts from the yohimbe tree have been marketed as dietary supplements for various purposes, but they contain highly variable amounts of yohimbine, if any; no published scientific evidence supports their efficacy.