Okay, so you're with your partner, and things are getting hot and she's ready to go, but, oh no, you can't get it up. Is it you? Is it her? Are you abnormal? Well, here's the deal. You're not abnormal; you're like millions of other guys that experience impotence (or penile erectile dysfunction) – some occasionally, some all the time.
There are a bunch of possible reasons it happens. Most are psychological, things like anxiety, stress or nervousness. Others are physical like poor circulation, injury or disease, fatigue, and definitely drugs, alcohol and smoking. Impotence, or penile erectile dysfunction, is the repeated inability to have or maintain an erection. Smoking increases the risk of erectile dysfunction. Diabetes, high cholesterol levels and drugs used to treat high blood pressure are also important risk factors.
During an erection, large quantities of blood flow, under pressure, into the penile arteries. This process is significantly impaired by smoking. If it's happening a lot, you should see your doctor to rule out the physical stuff.
Something even more common with guys is called "premature ejaculation.” It means that you're cumming too fast. Most of the time this happens when you are younger and have just started having sex. Many times it goes away with experience, even to the point where you can control when you cum. It can be frustrating to your partner, but you can work to improve it. Condoms help to reduce the feeling and most of the time, help with premature ejaculation. If you're real frustrated, talk to a doctor or health care provider about it. But remember, there's lots of other guys with the same problems so you are not alone. Hang in there.
There are other problems like "retarded ejaculation” which is not being able to have an orgasm even though you can get it up. Usually the causes are psychological like guilt about sex, fear of pregnancy or losing control, and difficulty letting go.
With any problem, it's important to talk to a professional about it – maybe a counselor or medical provider. You are definitely not alone. It's OK to ask for help if any of these problems aren't going away.