Right, as I understand it, impotance has two possible types of cause: medical and psychological.
Either your blood vessels are damaged because you are too fat or suchlike, or you freak yourself out by overthinking, and it doesn’t happen.
So.
I imagine the medical one is cured with viagra.
How do they cure the psychological one?
Counselling?
Viagra? (Show it’s possible)
Just don’t masterbate until critical mass is reached? 
I had a short bout of what I guess was psychological ED. It freaked me the fuck out, I had no idea why I “wasn’t working” anymore, was convinced that I would be like that for life, etc. When I went to the doctor she basically said that based on my age/health (late 20’s, healthy) it was probably psychological (which sounded like BS to me at the time), that it happens all the time, and not to worry. She told me to stop worrying, eat only healthy food with lots of fruits and vegetables, and increase my exercise (I exercise regularly already). If I didn’t get better in 2 weeks, call back and they’d recommend a specialist.
A week later I was fine. I suspect just talking to someone and doing something about it (changing diet, working out) was enough to snap me out of whatever funk I was in. My guess is that counseling/therapy combined with the placebo effect goes a long way.
You just needed a good stiff talking-to.
many cases of psychological disfunction are caused by anxiety. So anti-anxiety medications (eg Xoloft etc) can often help.
Except many anti-anxiety medications have been documented to interfere with sexual function. I’m not saying that lowering anxiety is a bad idea, but doing it with SSRIs can be counterproductive. Other methods (like cognitive behavioral therapy, exercise, or meditation) don’t have sexual side-effects.
You are way oversimplifying “medical” causes, most of which have nothing to do with damaged blood vessels. For many (most?) men, it’s caused by certain medications, e.g. those that lower blood pressure . . . often to the point where Viagra is useless.
I suppose. But don’t be too hardon yourself.
mmm
Psychological problems are just what they sound like. I am a firm believer in Better Living Through Chemistry, but and as an adjunct to any therapy for longtime psychological ET, it takes two to tango, as it were: you and your sexual partner. A huge amount of work sometimes has to be done there between the two of you.
Anxiety is too simple an answer in many cases.
This is true even for “medical” ED, which I have. Thanks to my wonderful partner, our sex life has not diminished at all . . . and without pills.
I’m just guessing – though I’ll guess it’s a good guess 
– but by making erection easier Viagra may help with psychological impotence. (Isn’t fear of poor performance a reason for impotence? This miracle drug will give you confidence!)
See if your friend can get a small dose and experiment. I’m lucky to live in a country where generic Viagra is available OTC for $1/pill (i.e., 50 cents a dose since I never take more than half a pill). Despite having no serious problem in my 60’s, knowing what I know now I’d have taken Viagra “recreationally” even in my 30’s or 40’s, had it existed.
I have read one test for determining whether ED is physical or psycological is whether or not a man still has nocturnal erections. If you still get morning wood, then it is psychological. Sometimes they use a test consisting of a thin paper tape secured around the flaccid penis before sleep. If the tape is broken in the morning, you had an erection, and any ED is probably psychological.
A few connected postage stamps from a roll is an easy home test.
The specific side effect of Sertraline (Xoloft) thats most commonly seen is taking longer to ejaculate, not problems getting an erection. Some users might see that as a feature not a bug 
This explains why so many disgruntled postal employees go on shooting sprees with their other guns.
SSRIs (including sertraline) are prescribed off-label to treat P.E. disorders in men (premature ejaculation). So you are exactly right.
This information is old, before Viagra, but back when I was in school this is the way they did it: Forbid intercourse for a couple of weeks and give the couple other things to do to work on intimacy, such as massages and extended third base, increasingly like intercourse each week. Since the problem was usually performance anxiety not trying to perform would take care of it and at some point the ability would come back. After a couple of succesfull sessions the problem would be cured.
It’s good to see you took matters into your own hands.
Heard about the old man who was arrested for assault with a dead weapon? 
(Rim shot!)
Bye now. (I’ll be here all week)
Two chicks at the same time
Need answer fast?