Taken from
http://www.sexinfo101.com/sh_drugs_2.shtml
"Amphetamines
Like alcohol, amphetamines, including methamphetamine and MDMA (ecstasy), “provoke the desire but take away the performance.” Amphetamines can increase one’s desire for sex. A male amphetamine user reports that, while amphetamines do not make him physically aroused, if he starts to think about sex while under the influence of amphetamines, he begins obsessing on sex and can’t sleep until he has had an orgasm.
In men, amphetamines often make achieving and maintaining an erection difficult. Conversely, in moderate doses, amphetamines occasionally cause priapism, a painful erection that will not go away on its own.
Male amphetamine users report that amphetamines cause shrinkage. Because of the erection difficulties and shrinkage amphetamines cause, men on amphetamines often find masturbation easier than sex.
In spite of the erection difficulties amphetamines cause, male amphetamine users find it possible, although difficult, to achieve orgasm while flaccid when they are on amphetamines. Some men report that they have never been able to do this, except when on amphetamines.
Men generally find it very difficult to ejaculate while on high doses of amphetamines. Some people see this as an advantage, because it allows men to last longer during sex. However, this side effect can also be very frustrating. Some men say that while masturbating on amphetamines it “feels like you’re gonna cum at any second, but you don’t.” They feel that the physical sensation of sexual stimulation is better while on amphetamines, but the overall experience is less enjoyable. “After a while, it’s like you just want it to be over with.”
Ejaculation can cause mild discomfort to men on amphetamines. Male amphetamine users report that ejaculation feels equally good and satisfying whether on or off amphetamines, but the testicles feel uncomfortable after ejaculating while on amphetamines.
In very high doses, amphetamines can cause spontaneous orgasm. However, doses this high are extremely dangerous, as they can cause convulsions, heart failure, stroke and death."
It's a regular occurence ld50 v ssri.
Ld50 v ssri is correct in advising to do a search. Here's some bluelight links for you:
http://www.bluelight.ru/vb/showthread.php?s=&threadid=108638&highligh
http://www.bluelight.ru/vb/showthread.php?s=&threadid=145562&highlight=penis+amphetamines
It's all caused my lack of blood flow to the nether-regions, or vascoconstriction.
"Three things must happen for an erection: 1) sexual arousal, 2) the communication of that arousal by the brain to the penis via the nervous system, and 3) expansion of the blood vessels that supply the penis, allowing blood to flow into the corpora cavernosa. If anything goes wrong in any of these three areas—arousal, the nervous system's activity, or vascular response—or in the balance among them, impotence can result.
The underpinnings of an erection lie in the twin corpora cavernosa, spongy cylinders running the length of the penis. To do their erectile work, they require a seven-fold expansion in their blood supply—an increase triggered by dilation of the dorsal and deep arteries serving the penis. Because erection and good circulation are so closely allied, anything that disrupts circulation— diabetes, atherosclerosis, nicotine, and certain medications" (Or recreational drugs) ", for example—can defeat erection as well."
Source Unkown.
This thread may be better moved to the Health Q & A section.
My question is: If lack of blood circulation down there is the cause, why does this happen when amphetamines increase blood pressure?