Antibiotics?

I think my first round of antibiotics was when I was 13 or 14. I didn't have them again until around 19, and I already had a lot of symptoms for crohn's at that point. I feel very lucky that I didn't take them more often, or my gut would have probably been worse. Antibiotics really mess up your gut flora, so I can see how they could be the gateway to bowel problems.

I have a cousin who took some sort of antibiotics for acne when he was a teen. He's had all sorts of gut problems since then, but no diagnosis other then IBS.