Rectal Bleeding During Bowel Movements: Causes & Concerns

Question
About twice a month I bleed from my rectum when I defecate. No pain, no blood before or after, just during defecation.  The only thing I can think of (because I do not engage in anal sex) is maybe there is a link to me drinking Redbull. Ever heard of this? I drink it once in a while and it dawned on me today that Redbull may be the cause.  I drank one today and within 30 minutes was in the bathroom seeing blood.  

Answer
I don't see how redbull could cause bleeding in 30 minutes.... this is probably from hemorrhoids or a fissure, esp. if you get constipated, but the rule is to look for the cause with a colonoscopy to make sure it isn't something like a colon polyp, or worse.

Hope this helps...