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Well, whatever turns you on basically but the science is this: erections occur when the small muscles in your penis, which are usually tightly contracted, relax and let blood start flowing in. The spongy tissue in the penis fills with blood and expands, pushing against the veins and closing them so the blood cannot drain out again. Well, you did ask.
There are two things that men complain about in the erection department — not getting one when you want one and getting one when you don't want one.
Not getting an erection when you want one is usually called erectile dysfunction (ED) or sometimes impotence. ED is a better description because the problem can usually be solved. In fact, nearly all men suffer from ED from time to time. The official estimate is that impotence affects about one in ten men at any one time. (Incidence increases from about one in 13 in men under 30 to one in two in men over 70.) But some surveys have put it as high as one in four.
It's no big deal. It's one of the things about being a flesh and blood human rather than a robot. Blokes who expect their penises to work like machines have not learned that yet. Don't worry about it but don't ignore it either. If it keeps happening, see a doctor.
Simply because ED can be an early warning of some serious health problems including:
Low testosterone levels are rarely the cause of ED.
Research suggests that men don't seek help with ED because they don't think it can be treated. This is not true. There are many causes of ED, some physical, some psychological.
There is usually a physical cause for ED — it is only purely psychological in about 25% cases - but whatever the cause worrying about sexual performance can make it worse. Anxiety contracts the muscles preventing blood entering the penis.
If you get erections at night or when masturbating but have problems with your partner, it's almost certainly not a physical problem so just relax. Chances are you'll live to at least 80 so there's plenty of time.
And, as usual, smoking is a non-no. Nicotine interferes with the flow of blood to the penis making an erection less likely. Smokers are 50-80% more likely to become impotent than non-smokers.
Getting erections all the time may not sound like a problem but it can be. It even has a name: priaprism. Young men can get sexually excited very easily so have a lot of erections. This can be embarrassing but it's not a problem and when you're older you'll probably remember the days fondly.
However, if your penis becomes hard for long periods or when you're not sexually excited you may have a condition called priapism. The condition is painful, and requires prompt treatment to avoid the risk of permanent damage to the penis and ED in the future. (As a guide, any man whose erection continues for four hours or more, should see a doctor.)
Have a look at our My erection won't go down FAQ page.
That's easy. We've a section on this site. But as all drugs can be dangerous and have side-effects, don't self-prescribe, talk to your doctor first. Read our section on erectile dysfunction first.
Date of last review 02/04/14
Date of next review 02/04/16