Contractions after sex

I'm aware that after sex you can have some contractions. I went through it with my first pregnancy as well. I know its normal. What I don't remember was how long they lasted. I had sex a few hours ago and just about an hour ago contractions started. I know its different for every one just wondering how long do the contractions last some of you after sex. Mines have been every 4 to 5 min for about an hour. Becoming extremely intense