The early news articles that I saw did mention diarrhoea, but not later ones.

My point was that I very much doubt that the panic buyers sat down with a calculator or pen and paper to work out how much toilet paper they normally consume over a specific period and therefore how much they may conceivably need if the supply becomes scarce. I doubt whether they even thought it through about whether toilet paper would become scarce and why. The definition of panic buying seems to imply a severe lack of rational analytical thought. (That's excluding the people who thought they would make a quick buck selling them at exorbitant prices.)

The people who now have a huge number of toilet rolls stored in their home are possibly looking a bit bewildered when they see how slowly their stash dwindles. A wall of toilet rolls today will still be a wall tomorrow and next week, and there will not be much of a dent in it even in a few months, even if they do contract diarrhoea.