If it's temporary and only happens occasionally, problems getting or keeping an erection aren’t cause for concern. There could be any number of reasons. It could be fatigue, stress, or even side effects of a medicine you just started taking.
But some men have a more frequent, longer lasting problem called erectile dysfunction (ED).
It’s more common in older men, but aging isn’t the cause. In nearly 75% of ED cases, there’s a physical cause. That means it’s time to see your doctor.