I had six months of FOLFIRINOX, which included irinotecan (300mg for the first two doses, then reduced to 220mg for the next ten). It's difficult for me to remember which drug caused which side effects but, if memory serves, we could be talking about diarrhoea. It was pretty predictable - the worst day was always four-five days after treatment - but it was really bad for only one day out of fourteen, and I stopped taking the anti-diarrhoea drugs (loperamide) early on as I found constipation to be worse. I had fruit for breakfast every day and stayed as mobile as possible. Hope you do ok with it.