Horny Goat Weed (Epimedium) may have testosterone-like effect

Epimedium, also known as horny goat weed or yin yang huo is one of many herbs used to treat erectile dysfunction in traditional chinese medicine. Besides its purported ability to enhance the libido, it has other traditional used to treat symptoms of a variety of health conditions, including arthritis, nerve pain, and kidney, joint pain, physical and mental fatigue and liver disorders.

Does Horny Goat Weed has Testosterone-like Effect?

Health professionals have long used horny goat weed to treat erectile dysfunction problems, to improve libido, and to restore sexual vitality [13].

The name Horny Goat Weed comes from observed increase in sexual intercourse frequency of sheep/goats that consumed Epimedium species plants. Nowadays, horny goat weed preparations can be found in all sorts of supplements including testosterone boosters across the world.

Recent investigations suggest that icariin is the most metabolically active component of Epimedium species [1]. Studies in rats provide some evidence that icariin possesses testosterone mimetic properties [2-4]. Regardless of its impact on serum testosterone, icariin does not impact pituitary luteinizing hormone expression [1]. It is therefore possible that icariin influences aromatase or 5-alpha reductase activity in vivo and thereby modulate serum testosterone levels without directly impacting luteinizing hormone secretion.

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Results of some animal studies also demonstrate that icariin may have a therapeutic effect on erectile dysfunction [5]. It’s sexual potentiating function seems to work via phosphodiesterase V (PDE5) inhibition [1,5]. The same was noted in Italian research where icariin’s ability to inhibit PDE5 was comparable to Sildenafil (drug used to treat erectile dysfunction) [9]. There is some evidence that icariin’s effects may go beyond PDE5 inhibiton as Alan W. Shindel and colleagues [1] detected significantly higher nNOS expression. Furthermore, it is suggested that eNOS was also up-regulated [1] but not all studies report that effect [5]. Study by Zhen‐Bao Zhang et al. [2] reported improved the condition of reproductive organs and increased the circulating levels of testosterone. Therefore, icariin may have therapeutic potential in the treatment of hypoandrogenism.

Pic 1. – Epimedium rubrum flower.

Icariin from Epimedium Sagittatum may Protect Against Cognitive Deficits

There is accumulating evidence that icariin supplementation also improves cognition in animal models.

Rui‐Xia Xu and assistants [6] investigated whether icariin has protective effects on learning ability and memory in a rat model of chronic cerebral hypoperfusion. Maze test revealed severely impaired learning ability and memory in untreated rats, while icariin-treated rats showed ameliorated chronic cerebral hypoperfusion-induced oxidative stress in the brain. This lead researchers to conclude that icariin protects against cognitive deficits induced by chronic cerebral hypoperfusion in rats.

Animal study by Fei Li et al. [7] demonstrated that icariin protected the brain disorder induced by D-galactose and improve the memory loss, as evidenced by the Morris water maze test. After 17 days of icariin supplementation to mice with brain inflammation induced by lipopolysaccharide, spatial learning and memory abilities were markedly improved [8].

Research also shows that horny goat weed (icariin) could potently inhibit the activity of enzyme called acetylcholinesterase (AChE) [10]. Acetylcholinesterase inhibitors are used medically for treatment of Alzheimer’s disease, glaucoma, and apathy. They are even used for prolonging REM cycle which increase chances of lucid dreaming [11].

Horny Goat Weed (Epimedium) Side Effects

Some horny goat weed extracts are possibly safe while others may not be when used for a long period of time or in high doses [12]. Long-term use of these other forms of horny goat weed might cause dizziness, vomiting, dry mouth, thirst, and nosebleed [12].

1. Shindel, Alan W., et al. “Erectogenic and neurotrophic effects of icariin, a purified extract of horny goat weed (Epimedium spp.) in vitro and in vivo.” The journal of sexual medicine 7.4pt1 (2010): 1518-1528.
2. Zhang, Zhen‐Bao, and Qing‐Tao Yang. “The testosterone mimetic properties of icariin.” Asian journal of andrology 8.5 (2006): 601-605.
3. Xiong, Y. B. “The study on the relation between icariin and gonad.” J Tradit Chin Med 26 (1995): 98-9.
4. She, B. R., et al. “The comparative studies on male reproduction effects between flavonoidys from Herba epimedii and flavonoids from Semen Cuscutae.” CJCM 6 (2003): 842-5.
5. Liu, Wu‐Jiang, et al. “Effects of icariin on erectile function and expression of nitric oxide synthase isoforms in castrated rats.” Asian journal of andrology 7.4 (2005): 381-388.
6. Xu, Rui‐Xia, et al. “Protective effects of icariin on cognitive deficits induced by chronic cerebral hypoperfusion in rats.” Clinical and Experimental Pharmacology and Physiology 36.8 (2009): 810-815.
7. Li, Fei, et al. “Icariin isolated from Epimedium brevicornum Maxim attenuates learning and memory deficits induced by d-galactose in rats.” Pharmacology Biochemistry and Behavior 96.3 (2010): 301-305.
8. Guo, J., et al. “Protective effects of icariin on brain dysfunction induced by lipopolysaccharide in rats.” Phytomedicine 17.12 (2010): 950-955.
9. Dell’Agli, Mario, et al. “Potent inhibition of human phosphodiesterase-5 by icariin derivatives.” Journal of natural products 71.9 (2008): 1513-1517.
10. Zhang, Y. D., et al. “[Inhibitory effect of icariin on acetylcholinesterase].” Yao xue xue bao= Acta pharmaceutica Sinica 47.9 (2012): 1141-1146.
11. Yuschak, Thomas. “Advanced lucid dreaming.” The power of supplements (2006).
12. WebMD.com “Find a Vitamin or Supplement – Horny Goat Weed” Retrieved 10. Feb 2013
13. James Meschino, D. C. “Natural Support for Sexual Performance & Libido Enhancement in Men and Women.”