Erectile dysfunction (ED) is defined as ‘the inability to achieve an erection sufficient for intercourse to the mutual satisfaction of both partners’. The exact prevalence of ED is unknown. This is largely due to variations in the definition of ED and because many publications focus on select population groups. However, it is estimated that ED affects 15 to 30 million men worldwide.

Although ED does not affect life expectancy, it can have a significant negative impact on an individual’s well-being and quality of life. There are many causes of ED but most important is the fact that this is an age-related phenomenon. The most reliable evidence for this comes from the Male Massachusetts Aging Study. This study reported that the probability of ED increased from 5.1% at 40 years of age to 15% at 70 years.

Other conditions such as diabetes, renal disease, chronic alcoholism, multiple sclerosis, atherosclerosis, vascular disease and neurological diseases account for approximately 70% of ED cases. NIH also reported that between 35 and 50% of men with diabetes suffer from ED. Furthermore, men taking many commonly used medications such as antihypertensive drugs, antihistamines, antidepressants, tranquillizers, appetite suppressants and cimetidine will experience ED as a side effect. Psychological factors can also cause ED, either in isolation or concurrently with an organic cause.

There are many herbal drugs that have been used by men with ED with varying degrees of success. Now that the Internet is one of the most readily accessible and comprehensive methods of obtaining medical information and treatment options, the general public may try many such herbal therapies.

1. Cola acuminata
Cola acuminata belongs to the family Sterculiaceae and its fruits are harvested from the forests of the Democratic Republic of Congo. The fruits are rough, mottled and up to 8 inches long and contain large, flat and bright red coloured seeds. Commonly known as cola nut, this fruit is used widely for the treatment of ED.

The fruits contain about 2% catechine-caffeine (colanine), which is believed to have a greater level of alkaloids (caffeine), thereby increasing the stimulatory effect. They are roasted, pounded or chewed and can also be added to drinks such as tea or milk or cereal such as porridge. InWest Africa this product is sold as a treatment for ED, although evidence for its effectiveness is limited.

2. Turnera diffusa (Damiana)
Damiana (Turnera diffusa) has been used as an aphrodisiac in Mexico for centuries. From 1888 to 1947, Damiana leaf and its elixirs were even listed in the United States National Formulary.

It is a small shrub that is native to Central and South America and belongs to the family Turneraceae. When this shrub blooms, small yellow flowers emerge with a smell similar to camomile. Its dried leaves and stems are used as a sexual stimulant in the form of capsules, liquid extract and tea.

Damiana contains flavonoids, resins, tannins and a glycoside called arbutin, which may reflect its many apparent therapeutic actions. In the renal tract arbutin is converted to hydroquinone, which in large quantities can cause the side effects of Damiana (nausea, vomiting, tinnitus, sudden death).

In scientific studies, Damiana has been found to relax the small muscles within the arterial walls of the penis, thereby allowing greater blood flow in the erect state. This relaxation has been found to be greater than that caused by Viagra (90% compared to 46%) and is thought to be one mechanism of how Damiana may work in ED.

In rat studies, Damiana was found to increase the sexual performance of impotent rats and increase the number of rats achieving ejaculation. The authors concluded that their study provided evidence for the folk reputation of Damiana. In animal studies, Damiana has demonstrated hypoglycaemia and therefore caution is advised in men with diabetes.

3. Polygonum multiflorum (Fo-Ti)
Fo-Ti (Polygonum multiflorum) is also called He shou wu, which translated from Chinese means ‘black-haired Mr. He’. According to Chinese folk legend, Mr. He was a village elder who took Fo-Ti, thereby restoring his black hair, youthful looks and vitality.

To date there have been no controlled human studies investigating the effects of Fo-Ti in men. In animal studies Fo-Ti has been found to enhance learning and memory and decrease the degeneration of nigrostriatal dopaminergic neurons in the brain. How Fo-Ti actually works in ED is unknown.

4. Ginkgo biloba
Ginkgo is among the oldest living species of trees and is therefore often referred to as a ‘living fossil’. The name biloba means two lobes and refers to the unique two-lobed leaves; its culinary and medicinal uses can be traced back for centuries.

It is one of the best-selling herbal drugs in Europe and the tree is known to survive only in China. It is believed that China produces approx. 63,000 kg of dried ginkgo seeds each year.

Ginkgo is believed to increase blood flow to the penis, although the evidence is contradictory. In an early double-blind study published in 1991, 50 men with arterial ED were administered 240 mg of ginkgo leaf extract daily for a period of 9 months. The men were divided into two groups based on their earlier response to conventional drug therapy for ED. The first group consisted of 20 men who had previously experienced some success with earlier treatments. The second group of 30 men had not experienced an erection with these treatments.

5. Panax ginseng (Ginseng)
Ginseng (Panax ginseng) is a perennial plant that is native to the damp woodlands of northern China and Korea. After the plant is harvested, the root is prepared in one of two ways, resulting in either white or red ginseng. When Panax ginseng is peeled and dried, the result is hard and yellowish-brown. This is white ginseng. When the root is steamed, peeled and then dried, the result is a deep red coloured red ginseng. In the Orient, red ginseng is preferred, whereas in the West, white ginseng is preferentially used in ginseng products.

Ginseng has been long alluded to in Chinese folk medicine as a sexual stimulant, and there appears to be some scientific truth to this. In animal studies, a concentration of 1 mg/mL of ginseng extract relaxed corpus cavernosal tissue in rabbits. This action was mediated by an increase in the sequestration of intracellular calcium and in the corpus cavernosal sinusoids by an increase in the release of nitric oxide (NO). The increase in NO is a positive finding because NO is the main mediator of penile erections and cyclic GMP, which mediates the relaxing effect of NO on penile vascular smooth muscle.

6. Epimedium brevicornum (Horny Goat Weed)
Horny goat weed (Epimedium brevicornum) is also known as Yin Yan Huo and has long been used in traditional Chinese medicine to treat disorders such as dementia, fatigue, ED and arthralgia. It is derived from a leafy plant that is native to Asia and the Mediterranean.

According to Chinese folk legend, horny goat weed’s use for ED started after a Chinese goat herder noticed increased sexual activity in his flock after they ingested horny goat weed.

In one study testing the oestrogenic activity of 32 herbs, horny goat weed was one of the herbs to have greatest oestrogenic activity, suggesting a potential use in menopausal patients.

7. Lepidium meyenii (Maca)
Maca (Lepidium meyenii) has a radish-like root and is often called ‘Peruvian ginseng’. Although unrelated to the ginseng family, its use is similar to ginseng in that it can increase energy, libido and sexual performance. Maca has been used as a food in Peru for many centuries but has only recently gained popularity as an herbal supplement.

In one study involving 9 adult men, 4 months of treatment with maca tablets resulted in increased seminal volume, sperm count and sperm motility.

8. Ptychopetalum olacoides (Muira Puama)
Muira puama (Ptychopetalum olacoides) is a small tree that is native to the Amazon river basin. It has long been used for sexual problems in Brazil at a dose of 2 to 4 mg of liquid extract per day. To date there is no evidence to support the use of muira puama for ED.

9. Eurycoma longifolia (Pasak Bumi)
Pasak bumi (Eurycoma longifolia) is a tree found in Indonesia, Thailand and Malaysia (tongkat ali). The root of this tree is reported to enhance male sexual performance as well as having medicinal properties for use in the treatment of dysentery, fever and other ailments.

Years ago the roots had to be brewed for long hours to obtain the active extract. However, it is now widely available in the form of a pill or a tea bag.

10. Ganoderma lucidum (Reishi)
Reishi (Ganoderma lucidum) is a fungus that grows from the tops of stumps or submerged logs and is found in most parts of the world. Historically in Japan, reishi used to hang in the hallways of all homes to ward off evil spirits and was carried by brides into their new homes to guard against ‘grave’ matters in the new family.

Reishi has many uses in traditional Chinese medicine, including ED. In a study in China of 60 men with ED, there was a significant benefit after drinking a decoction made using fruit bodies of a member of the Ganoderma family for 1 month. Only 4 patients reported no improvement; 17 patients reported slight improvement; 25 men claimed marked improvement in their sexual function, and 14 men reported that they were cured. No other drugs were taken during the period of the study.