Hi cactus,
I know if I don't drink enough water with my CDS doses that it burns my throat a little. You are not diluting the doses with much water so that might be a factor. I don't get coughing from the CDS, except that I have noticed it is very good at breaking up phlegm in my lungs. It happens almost immediately after taking a dose and I'll cough up some of the loosened phlegm. If he has chest congestion, then the coughing may be good in that it means he is getting it out.
If he does not have chest congestion, then maybe it is irritation from not enough dilution or at least this could be a contributing factor. I am taking hourly doses of CDS but have not tried taking them with only a little dilution each hour.
It does seem also that it could be possible the coughing is a sign of healing. In my experience, the CDS is very powerful, more than MMS1 for me, but does not cause nausea and diarrhea problems. It is really hard to know what is going on here since you cannot talk to him to find out if the doses are burning his throat.
Michael