Nutu I am half way through my RT 20/37. I keep a bottle of lactolose in my cupboard and as soon as I get any early signs of constipation I take a dose. Fortunately have not had any issues with it so far although one session I did have gas but a 30 minute walk soon fixed that. Lots of drink, 3 litres minimum and a maximum of one cup of coffee per day has helped so far.