We’ve all heard the ED commercials that warn about priapism and to consult a doctor if you have an erection lasting more than four hours. Isn’t a three hour erection a serious problem too? It sure sounds like it to me.
This is purely hypothetical. Trust me.
I think you need a doctor and and a lengthy explanation to cover all the relevant issues. Through my mid-20’s, I was completely a multi-ejacaculatory male and could maintain a natural erection for over 6 hours. It got sore but didn’t cause any real problems. I have no idea what I could pull off now in my 30’s but things may be be quite different for a 60 year old on a little purple pill.
I had that problem once and went to the emergency room. They were busy but the nurse said she could squeeze me in.
Hell, I’m in my mid 40’s now and can maintain an erection (by choice) for three hours with the right stimulation, without drugs. Has never caused me any problems.
I would think the problem would be if;
a> You’re taking drugs to help you get an erection, and
b> You don’t have a choice about having that erection. Meaning that it’s involuntary and you can’t get rid of it, even post ejaculation.
THEN there would be issues and potential injury.
From the time when I was thirteen until I was about 25 I had a non-stop, 24/7/365 erection. After that until I was 40 I was only erect while I was awake and a few hours while I slept and then a few hours before I woke, so only for about 23 hours a day.
Now that I’m almost 48 I only get one about 16 hours a day. So I figure by the time I’m 90 I’ll be down to 3 lousy hours a day. Then I’ll be scared and call my doctor.:eek:

Surely you have enough material for a TV sitcom …
whut?
Heh.
I just wanna know, if I had an erection for 3 hours, what would I do for the other 2 hours and fifty five minutes?
Man oh man, this statement does not inspire confidence.
I’m fond of saying, “If you have an erection, lasting longer than 4 hours…call a prostitute!”
Heck, I’m almost 67, I’d settle for a 3 minute erection never mind 3 hours
It’s not okay, it’s gr-r-r-R-EAT!!!
I saw what you did there. 
I was told the risk is that with an erection the blood flow to the penis is restricted, so if you’re erect too long the flesh can actually start to die.
Don’t want that now do you?
The idea with these drugs (I’m thinking Cialis, specifically) at least, according to the commercials, is that they’re ready when you are, right? So, you take one, but it still requires stimulation for you to get hard, right? Does a 3 (or however many) hour erection mean you don’t come that whole time, or that you come and it just doesn’t go down?
I don’t think ejaculating is the problem. As was posted before, it seems to be the constant flow of blood to the penis. I’m not sure how these medications work, but I imagine that one could rupture a blood vessel (down there), cause serious drops (or raises) in blood pressure, and possiblly even fainting due to the transfer of blood from head to another head. 
Wouldn’t it be embarrassing to have the erection for 3 hours, drive to the hospital, then lose it during the 2-3 hour wait typical of emergency rooms? What would you tell the doctor? I had it here a few minutes ago but lost it after only 5 hours?
Because any trip to the emergency room takes over 3 hours, all men should rush to the hospital at the first sign of an erection. If it’s done its work (a matter of minutes) and is still staring up at you, it’s time to panic NOW.