So Your Butt Is Bleeding...
First things first: while serious injuries caused by anal sex are rare, some mild bleeding after anal sex isn't. Partha Nandi, a gastroenterologist and health editor with WXYZ-TV in Detroit, said the most common reason for bleeding after anal sex is anal tears — small tears or fissures in the delicate anal canal tissue. Shilpa Ravella, a gastroenterologist in New York City, said the tears typically reside internally, because the "inner anal tissue can be more sensitive and prone to tears than external tissues." A lot of anal tears are so small that they don't bleed and you often won't notice if you have one, but they can absolutely cause a bit of bleeding that lasts anywhere from a few hours to a few days. Another common cause of bleeding can be an internal hemorrhoid you didn't know about until, poof, it burst during anal sex. Most people report that hemorrhoids make anal sex uncomfortable or painful and because a hemorrhoid is literally an enlarged, swollen blood vessel, they can certainly cause anal bleeding after sex. Bleeding should subside within a few days.
When It's More Than a Little Tear
Severe or prolonged pain is never something to be ignored — especially when it's radiating from your butt. While a new sensation (like something going up a place that usually only sees things going out) may be a bit uncomfortable at first, anal sex should never hurt (no sex should ever hurt). If you're experiencing significant discomfort or pain after anal sex, you should see a doctor. You should also see a doctor if your pain persists for more than a few days, or gets worse with time.
How to Avoid Bleeding
There's no way to overstate the importance of lube. Lube is your best friend in any sexual situation, but because the rectum doesn't self-lubricate in the same way the vagina does, it's especially crucial for all things butt. This includes anything from full-on, penetrative anal sex to minor butt play with a finger or a toy. Don't ever force anything up into a hole that's already delicate and sensitive. Lube, lubricated condoms and then even more lube are the biggest saving grace for easy anal sex.
The rectal sphincter is strong and small — attempting to jam anything through it too quickly is going to be painful. Ravella suggested proceeding “cautiously - and stop if the sex becomes painful." Nandi added it's not uncommon for people to jump into rough anal sex too quickly and experience tearing or bleeding because they didn't exercise enough precaution. It's not a sprint, it's a marathon back there. And you want to make to the finish line without any bleeding or discomfort. Oh and of course you want to keep it safe!