What stops an erection from happening?

Dr. Michael Roizen, MD
Internal Medicine

One minute, your penis is at ease. The next, something is arousing you (if you’re married, let’s hope it’s your wife), and suddenly your soldier is standing up and saluting. What happened? Your brain sent a signal to your central nervous system, releasing a compound called nitric oxide. This compound stimulates the smooth muscles of your penis to relax, allowing blood to flow into tiny, tiny pools. The veins around these chambers get squeezed by these expanding pools of blood, so the blood can’t escape. Your penis gets erect. If you’re really lucky, it stays that way until you ejaculate.

It’s a beautiful symphony! But just like the Philharmonic, an ejaculation can get interrupted. In the concert hall, it might be a cough, or a loud candy wrapper. In your body, many things get in the way. If you are overweight, don’t exercise much, smoke, or have cardiovascular problems, your blood may not be flowing easily. Your arteries may not dilate properly because they are inflamed or clogged. If the inner lining of your arteries is damaged by cardiovascular disease, you don’t make nitric oxide as easily -- no matter what your brain is telling you to do (not to mention the lovely lady next to you in bed).

Every man finds that his symphony gets interrupted once in a while. But if this is happening to you more than half the time you attempt an erection, talk to your doc about underlying reasons that may interfering. Think of your penis as a dipstick for your health. A problem with erections may be nature’s way of telling you to take better care of your heart and your health.

When erection ability fails or begins to decline, many men and women are all too quick to take it personally or worry that an erection problem means that sex has to end. The truth is, an erection is the result of an intricate dance between the brain, the nervous system, a man's emotions, and the body's network of blood vessels. As soon as one gets off balance, the whole dance can be affected. Just about anything that interferes with brain function, nerve function, or blood flow can lead to trouble with erectile function.

Perhaps the most common cause of erectile problems -- at least among young, healthy men -- is performance anxiety. Many cultures place pressure on men to be the "experts" when it comes to sex, which can make men feel like they have to be responsive for sex or know how to please their partner every time. This pressure can be stressful and make it more difficult to get or maintain an erection.

Health issues can also cause erectile problems, particularly among middle-aged and older men (though health-related erectile issues can occur at any age). Common age-related health conditions such as high blood pressure, diabetes, and prostate cancer can interfere with erectile function, as can the medications and procedures used to treat them. High blood pressure and heart disease often limit blood flow to the penis. Diabetes, if left untreated, can cause nerve damage, making adequate physical stimulation of the penis more challeging. Surgery for prostate cancer can affect blood flow and the mechanics of erectile function. Hormonal disorders that interfere with testosterone production and a variety of other health conditions also can be the culprit, which is one reason it's important to get checked out by a physician. Recent studies have found that difficulty getting or maintaining an erection might be an early sign of heart disease. Lifestyle choices can affect erectile function, too, mainly by interfering with blood flow to the penis. Excess weight, a lack of exercise, poor eating habits, cigarette smoking, and alcohol and drug use can all contribute to erectile problems. Often, treating the underlying physical problem goes a long way towards resolving erectile problems.

While the majority of erectile problems are related to performance anxiety or a man's physical health, other psychological factors can be at work, too. Depression, stress, grief, anxiety, and fear or guilt about sex all can cause erectile problems, as can relationship problems.
Dr. Mehmet Oz, MD
Cardiology (Cardiovascular Disease)
It's not rocket science: The more blood flow a guy has to his penis, the firmer the erection. Erections happen when blood fills up the penis and remains there. Here's how it works: Once you're sexually aroused, your brain sends signals to your body to increase blood flow down south. It is a physiological version of poker's all-in. If the nerves are damaged, and the message doesn't get through, your penis won't rise to the occasion. If a physical condition such as cardiovascular disease keeps the blood from flowing like Niagara into your penis, you won't get an erection. Weak or no erections should prompt a call to your doctor, so you can get to the root of the problem.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.