Epimedium extract is a 'tonic-type' herbal supplement, not a stimulant. In other words, it takes a few doses to a week before you start noticing its sexual enhancement effect.
 

Epimedium
 

Research has shown that epimedium extract can inhibit an enzyme called acetylcholinesterase (AChE). AChE rapidly stops neurotransmission at cholinergic synapses like those found in the brain and at neuromuscular junctions, which are needed for speedy responses in the neuromuscular system. By inhibiting AChE, Horny Goat Weed supports higher levels of the key cholinergic neurotransmitters associated with sexual arousal.

Icariin, a component of epimedium extract, A potent vasodilator with anabolic and anti-catabolic effects, works through several different mechanisms:

1.by increasing nitric oxide (NO) through PDE5 inhibition,

2. by acting as a potent anti-catabolic agent that increases the testosterone to cortisol ratio,

3.by increasing muscle contractility by deactivating AchE (Acetycholinesterase),

4.by boosting endogenous testosterone levels through increasing cAMP and luteinizing hormone and decreasing prolactin. It also is considered a Phytochemical Selective Androgen Receptor Modulator or P-SARM. A P-SARM is a phytochemical (plant-derived) compound that mimics the effects of androgens on muscle mass, strength, bone growth, drive, and sexual function, while at the same time not negatively effecting blood lipids or blood pressure.
 

As mentioned before, Icariin has potent anti-catabolic effects, along with testosterone-mimicking and muscle-contraction-enhancing benefits - several studies have shown that it actually competes with glucocorticoids for receptor sites in a manner similar to testosterone, while at the same time improving the testosterone to cortisol ratio. This is caused by two different mechanisms of action: the aforementioned competition with glucocorticoids, and also increased testosterone production, through increased cAMP (cyclic AMP, a second messenger important in hormone signaling) levels, luteininzing hormone (LH) levels, the actual mimicry of testosterone in spermatogenesis, and decreased prolactin levels. Icariin seems to block glucorticoids from binding to cortisol receptors, thus blocking the action of cortisol. This alone will cause an anabolic effect by positively skewing the T:C ratio, which is a trigger for greater protein synthesis, increased aggression towards the iron, and insane muscle contractions
 

Related herbal plant extract: common cnidium extract,polygonum cuspidatum extract ,yohimbe bark extract