Can poison oak cause diarrhea?

Extremes: You would have to have a very serious case of poison oak that was causing systemic symptoms and not just skin symptoms. These type of reactions are very rare. However, when they do occur, prostaglandins can be released in your body in response and these can cause cramping and diarrhea. Again, a very rare occurrence.

Unlikely: I would think it unlikely that exposure to poison oak would cause diarrhea. I suppose if you ingested it, there might be some inflammation of the GI tract, but skin exposure is unlikely to cause diarrhea. Good luck!