It can be difficult to say exactly how long the average erection lasts. Many factors can contribute to the overall length of time., For someone who reaches orgasm very quickly, this period of time is shortened because the penis usually stops being erect after ejaculation., For people who last longer during sex or have a sexual encounter that’s drawn out over a longer period of time, an erection can last much longer., But, on average, an erection lasts for the length of a sexual encounter — around 7 to 13 minutes., Medications that help someone have an erection, like Viagra and Cialis, allow blood to flow more easily to the penis. In many cases, they can cause a longer erection., However, if your erection lasts longer than 4 hours, seek immediate medical attention. You may be experiencing priapism. This is a serious medical condition where blood is unable to flow out of the penis. It can cause severe or permanent damage if left untreated.