(K.Schum.) Pierre ex Beille
Pausinystalia johimbe, (Rubiaceae), common name yohimbe, is a plant species native to western and central Africa (Nigeria, Cabinda, Cameroon, Congo-Brazzaville, Gabon, Equatorial Guinea). Extracts from yohimbe have been used in traditional medicine in West Africa as an aphrodisiac and have been marketed in developed countries as dietary supplements.
Yohimbe is one of five Pausinystalia evergreen species growing in West and Central Africa in lowland forests. The tree grows about 30m tall, with a straight bole that is rarely larger than 50–60 cm in diameter. The bark is grey to reddish-brown, with longitudinal fissures, easy to peel and bitter-tasting. The inner bark is pinkish and fibrous. The sapwood is yellowish and the heartwood is ochre-yellow; the wood is fine-grained and relatively dense and moderately hard. The leaves grow in groups of three, with short (about 2 cm) petioles. The blades are oval-shaped, 11–47 cm long and 5 – 17 cm wide. The demand for yohimbe bark has led to over-exploitation, with the possibility of long-term threat to sustainability of the species. Cameroon is the biggest exporter.
Extracts from the bark of yohimbe are used in West African traditional medicine in the belief it is an herbal tonic or an aphrodisiac. Yohimbe bark and extract are used in manufactured dietary supplements, but there is no scientific evidence they have any effect. The levels of yohimbine present in yohimbe bark and manufactured supplements are highly variable.
Although proposed as a potential treatment for erectile dysfunction in humans, there are cautions about its safety or effectiveness. Side effects of using yohimbe, particularly in high doses, may include high blood pressure, increased heart rate, headache, nausea, tremors, and insomnia.
Over-exploitation of the tree for its bark has led to concerns that P. johimbe is becoming an endangered species.
Yohimbe bark extract and yohimbine specifically have been declared as insufficiently characterized and possibly unsafe to consume by the European Union and US National Institutes of Health. .[additional citation(s) needed]