I was told at my training day (March 2006) that the only laxative you could take was Ducolax as all of the others could potentially knock you out of ketosis. Plus the best preventative was Cambridge Fibre 89.
Sennokot is okay, physllium husks okay, Fybogel natural only not flavoured, but not dulcolax. It used to be allowed but several people have had severe pain and collapsed after using this on a VLCD so it is now not recommended. Prevention is better than cure so Fibre 89 should be used from the outset.
Once constipation is over then introduce the Fibre 89 daily to prevent reccurrence.
I made the mistake of taking Dulcolax - never again. It was the most severe abdominal pain I have ever experienced and it lasted 24 hours. I now use Fibre 89 as a preventative but it doesn't work as well as I would like. Unfortunately nor do husks so I am just putting up with it for now.
I thought I'd get some from Asda last night as I've been feeling a bit bunged. My fiance and I did aa experiment with a pint of tea made from 4teabags (don't ask) that I heard of on another site. Was rubbish, we just ended up with banging heads.
So anyway, I popped 2 pills when I was driving home from Asda. All was fine until about 3am this morning, woke up with mega wierd belly ache, went to the bathroom, started sweting profusely, had some scary diarrhoea, then was sick, then lay half naked on the landing as I was too dizzy to go back to bed. Bad stuff, not sure I'll be brave enough to try again.