Recreational drugs (including immoderate alcohol use) and testosterone just do not go together. Ecstasy is no exception. A lot of young men are using or have used Ecstasy (MDMA or MDA) and do not realize that they are lowering their testosterone because of it. In fact, some experts feel that permanent damage can occur. It's an easy trap to fall into, because one thinks, "Well, Ecstasy is a 'brain thing' and not a 'testes thing,' so it can't hurt my T." What they don't realize is that testosterone IS a brain thing: testosterone production starts at the hypothalamus after all.
And we have already had a couple of guys show up at the Peak Testosterone Forum with low testosterone and a history of Ecstasy usage. For example, look at what this young guy wrote:
"Drugs - I have taken ecstasy, some cocaine and amphetamines (about 15 times altogether) when I was 18-20. Smoked pot occasionally, but completely drug free in the last 4-5 years. I am currently looking at my testosterone readings - 12.69 nmol/l, which is about 373. Not that low, but still way below that I read is normal for 26 y.o. guy. Additionally, my test included some other hormones like FSH, where I got 1.11, which is below the reference of 1.5-12.4; and LH of 2.53 IU/l (1.7-8.6 ref. values). I mean, the general blood work is perfect..." 
Of course, it's impossible to know if Ecstasy is really responsible for his low testosterone levels of 373 ng/dl. It could also have been the cocaine or marijuana use as I document in my links on Testosterone and Marijuana and Cocaine and Erectile Dysfunction pages. However, the pattern fits well: his LH and FSH are on the low side, indicating secondary hypogonadism and suppressed upstream testosterone signaling.
Now what is interesting is that physicians and researchers were hearing reports of lowered HPA function and decreased testosterone from Ecstasy when it first became popular. There was even an early research paper that looked at whether it was the Ecstasy lowering the testosterone or actually the simultaneous marijuana usage that usually is concomitant it. And the conclusion was that it was probably the marijuana.
However, as time went on, still other research clearly showed that Ecstasy could in and of itself lower T and that it can alter the entire HPA axis. And, as I will discuss below, a study from just a few years ago showed that it can permanently damage neurons, but first let's start with a 2008 animal study on rats that showed that chronic (15-day) Ecstasy administration lowered the animals LH and FSH by about half and their testosterone even more significantly.  Furthermore, progesterone was suppressed which will likely lead to cortisol-related issues, including fatigue and achiness.
What is very interesting is that Ecstasy is really kind of a "fake orgasm." "Ecstasy" is a good name for it. It gives a "high" that is, from what I have read, somewhat like the feeling that you have post-orgasm. Life is good and pain free and one is in love the world. The researchers above noted that it stimulates serotonin, dopamine, GABA, noradrenaline and acetycholine. Likewise, an orgasm sends out a flood of neurotransmitters.
Of course, the clear difference is that an orgasm (in sexual intercourse at least) will generally increase testosterone, something I discuss in my link Why Sex is Good For You. In contrast, Ecstasy likely damages the brain and permanently lowers testosterone depending on how much and how often you have used it. And that leads to the obvious question, "Why not just stick with sexual intercourse?" It's really hard to argue with Mother Nature, eh?
Two years later an even more sobering study came out that showed that Ecstasy probably damages brain cells.  Scientists noted that chronic Ecstasy users had lower levels of SERT, a transporter protein for serotonin, which indicates actual neuronal damage. And what is downright frightening is that they found this damage in those only using Ecstasy twice per month. Even worse, as the damage occurs, users find they have to take greater and greater dosages, which likely inflicts an ever increasing amount of damage. Now we have an explanation as to why so many young men that have been Ecstasy users are reporting low testosterone. (Cortisol levels also appear to be permanently damaged which just adds to the underlying issues.)
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NOTE: Does Ecstasy have a higher use? One interesting story, at least in my opinion, is the Dr. Andrew Weil endorsement of Ecstasy. I almost always enjoy Dr. Weil's articles and commentary and love his integrative approach of combining the best of alternative and Western (allopathic) medicines. I think the two make a much potent and productive whole and could list many examples of that. Dr Weil is one of the leading clinicians exemplifying this approach and my hats off to him for this.
However, one very curious thing about Dr. Weil is that he was a "60's child" and, as a student at Harvard, actually broke the story of Timothy Leary and Richard Alpert's experimentations with LSD. He also wrote a book a few year's later called The Natural Mind: An Investigation of Drugs and the Higher Consciousness.  Ecstasy has also captivated his attention and he wrote an article called "The Love Drug" apparently that praised its abilities to put someone, including himself, in a rather sublime state of mind.
He even went so far as to write in this article that "In the right hands, MDA is quite safe. Out of hundreds of experiences with it htat I have observed, I have seen only three anxiety reactions. The medical potential of the drug is great and quite unexplored. I have noted repeatedly that people under the influence of MDA, when feeling high, centered, and free of desire, are in a state complete anergy - that is, they manifest no allergic reactions, even to allergens to which they have a lifelong sensitivity. Asthma disappears, hay fever disappears, cat allergies go away, and there are even no responses to mosquito bites. This effect is temporary and appears to be the analogue in the body of the mental experience of complete relaxation and lack of anxiety. It might be reproducible without the drug if we could learn to spend more time in that state."
I don't know what Dr. Weil's current position on Ecstasy is, but I urge you to stay away from the stuff: it's just not worth the risk. Remember that it seems to dramatically affect the HPA axis at relatively low dosages and frequencies. Exactly where that cutoff is is not known and cannot be ethically determined, so you're taking your health (and testosterone) into your own hands by experiementing wtih MDMA.
2) Multidisciplanary Association for Psychadelic Studies, May 25 2010, "Ecstasy may damage brain cells, study finds"