At first thought, a four erection might sound like a great problem to have. But be careful what you wish for. When an erection lasts for more than four hours it means the affected person has priapism a condition you must take seriously — all kidding aside. In the list of disclaimers for ED ads, mention of erections lasting longer than four hours is always front and center — and when the disk jockey tells you to call your doctor if this happens to you, that’s not just a frivolous bit of advice !