I was looking into this the other day for some other guys:
When I was in my 30's and 40's I took pride in being able to last until my partner came a couple of times before I came. Now that I'm in my 60's unfortunately it can take an hour or more before I cum.
This sounds like a condition known as "delayed ejaculation". It can have various physical or psychological causes, usually the latter. It can be related to aging, alcohol or tobacco use, medicines, surgeries, stress, blockage of ducts, masurbation, various diseases, being overweight, allergies, etc.
"Delayed ejaculation is the inability to ejaculate or persistent difficulty in achieving orgasm despite the presence of normal sexual desire and sexual stimulation. Normally a man can achieve orgasm within 5 minutes of active thrusting during sexual intercourse, [1] whereas a man with delayed ejaculation either does not have orgasms at all or cannot have an orgasm until after prolonged intercourse which might last for 30–45 minutes or more. In most cases delayed ejaculation presents the condition in which the man can climax and ejaculate only during masturbation, but not during sexual intercourse."
http://en.wikipedia.org/wiki/Delayed_ejaculation
"Delayed ejaculation — sometimes called impaired ejaculation — is a condition in which it takes an extended period of sexual stimulation for a man to reach sexual climax and release semen from the penis (ejaculate). Some men with delayed ejaculation are unable to ejaculate at all.
"Delayed ejaculation can be temporary or a lifelong problem. Possible causes of delayed ejaculation include certain chronic health conditions, surgeries and medications. Treatment for delayed ejaculation depends on the underlying cause.
"It's normal for men to have delayed ejaculation from time to time. Delayed ejaculation is only a problem if it's ongoing or causes stress for you or your partner.
http://www.mayoclinic.com/health/delayed-ejaculation/DS01174
after taking some vitamin V it is really difficult to finish. I haven't found anything that makes the prong more sensitive (after doing an online search I even tried some african tree sap butter...didn´t work) so I'm stuck in the same situation...
As per the above, I'd recommend seeing a competent doctor. Perhaps vitamin V is the problem & you should consider trying something else:
"There is yet no reliable medication for delayed ejaculation. PDE5 inhibitors such as Viagra have little effect. [10] In fact, Viagra has a delaying effect on ejaculation, possibly through additional effect in the brain or decrease of sensitivity in the head of the penis. [11] Case studies have reported some success with serotonin antagonists (amantadine) and dopaminergic agents (bupropion, buspirone) , though large, controlled studies are lacking, likely due to the rarity of the condition relative to other forms of male sexual dysfunction."
http://en.wikipedia.org/wiki/Delayed_ejaculation
"If you have trouble maintaining an erection or reaching orgasm, ask your doctor about medications or other treatments for these problems.
http://www.mayoclinic.com/health/senior-sex/MC00057/NSECTIONGROUP=2
"the vast majority of men who suffer from delayed ejaculation problems get checked out physically and are told that there is nothing mechanically wrong with them."
http://www.youtube.com/watch?v=I1kP5miFRAc
"For some men, stopping or cutting down on the use of alcohol, tobacco, or illegal drugs may improve their ability to control ejaculation."
http://www.healthlinkbc.ca/kb/content/special/tv7761spec.html
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