Are you a male with libido problems? If so, then you may still be in disbelief. Wasn't it just yesterday that sex was about all you could think about? Now you find yourself thinking about just because you know you should!
Or maybe you're a male who just wants to enhance your sexual desire using some scientifically-backed male libido supplements? Well, we have good news: there are several legitimate, scientifically-verified such supplements that seem to work quite well on the male brain.. Yes, it's Christmas at Peak Testosterone.
However, one should keep in mind that there are several medical conditions that can cause waning libido, almost all of which should be checked by a doctor. For example, no male libido supplement on planet earth can help stimulate you if you are low in testosterone. Testosterone is simply too intimately tied to male libido. Read this link on Low Testosterone Symptoms if you think that might be an issue. Lack of sleep, depressed immunity, depression, stress, relationship issues and many other things can do the same.
So get checked out with your doc and then consider these male libido supplements, all of which have a study (or more) showing their ability increase sexual desire:
1) Maca. We have already covered Maca's sperm and erection enhancing properties in our discussion of Maca and in our Erection Supplementation Guide. But what you may not know is that Maca has had a reputation for centuries among Peruvians for its libido-increasing powers among male tribal members. And animal studies bear out the ancient wisdom. 
In fact, one animal study turned rats into rabbits. Don't believe me? It all started when researchers studied rats and put one male rat in with two virgin female rats. Rat heaven, eh? Researchers were astonished to find that each male rat entered, i.e. penetrated the female rats over fifty times in a three hour period!  When is the last time you did that, mate? This greatly exceeded the number of penetrations performed by the Maca-less rats. Those rats just couldn't get enough.
2) Muira Puama. Maca comes from Peru. Muira Puama comes from the same continent in Brazil. Most of the studies on Muira Puama's aphrodisiac qualities have been done by a Frenchman. But, then, who better to study an aphrodisiac than a Frenchman, right? One of his studies on human subject showed that about 2/3 of low libido participants were helped by taking Muira Puama. 
3) Tribulis Terristris. Tribulis is tremendulis and fantabulis. We have covered this herb elsewhere, including How to Improve Testosterone and Super Sexual Herbs, but made scarce mention of the fact that Tribulis Terristris also has evidence of being a decent male libido supplement at least in animals.  It seems to work this magic by increasing DHEA and Nitric Oxide.
4) Ginseng. Korean Ginseng was shown in one study to improve erectile strength and function in a number of ways, including boosting the beloved Nitric Oxide.  This same study found that Ginseng boosted libido and other animal studies have implied that sexual desire is enhanced by this herb as well.
5) A specific extract of the food and spice Fenugreek has been shown to be a significant libido and orgasm booster. For more information, see my link on The Benefits of Fenugreek. (There are a couple of Cautions with this herb as well.)
CAUTION: Yohimbe is often added to proprietary preparations for libido enhancement and erectile dysfunction. Avoid this as it can increase blood pressure.
CAUTION 2: One male libido supplement that gets some press is Damiana. However, it's powers are poorly documented and debatable in males anyway. In addition, it has been shown to be estrogenic, the last thing most of us guys need. 
CAUTION 3: Some pills are what I would call an anti-aphrodisiac. Beta blockers (for high blood pressure/arrythmias) are notorious libido reducers. Cimetidine (Tagamet) for stomach acid is another interesting case, because it can actually cross the blood-brain barrier and somehow interferes with sexual desire in many patients.  Dopamine is, in general, associated with an increased sex drive and seratonin with the opposite. For this reason, almost all common antidepressants can lead to a loss of libido. In fact, the research shows that a great many of the antidepressants lead to loss of libido, erectile dysfunction and delayed orgasm. 
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2) Urology, Apr 2000, Qun Yi Zheng
3) Ethnopharmacology, Mar 1995, Male Sexual Asthenia - Interest in a Traditional Plant Derived Medication
4) Ann Acad Med (Singapore), Jan 2000, 29(1):22-26
5) Int J Impot Res,Sep 1995,7(3):181-6, "Clinical efficacy of Korean red ginseng for erectile dysfunction"
6) Journal of Ethnopharmacology. 120:387-393, "Anti-Aromatase Activity of the Constituents from Damiana (Turnera diffusa)"
7) Can Med Assoc J, Aug 18 1979, 121(4):404ï¿½405, "Diminished libido with cimetedine therapy"
8) Indian Journal of Medical Sciences, 2001, 55(3):139-148, "Antidepressants induced sexual dysfunctions"