I have had this issue for a few years now and I can not pinpoint if it is the detergent or the toilet paper causing this.
I use extreme caution but the allergic reactions have only occurred at my parents house. I have done numerous allergy tests and all cane back negative.
My parents switched to free and clear detergent and I did not have a reaction for months. This past weekend, my mother was in a hurry and used Tide powder instead.
Within minutes of helping her fold a load of laundry I felt extremely painful itching in my vaginal area along with facial tingling and swelling - hives formed in my lips chin and face.
Has anyone else experienced something like this? Could it be the toilet paper?
Best way to find out is by process of elimination, next time you go to your parents try taking your own toilet paper and only use that then try taking some of her detergent powder home and do a little of your laundry in it.
I take it you use different brands of both items to what your parents do?