notmorecraft

Check which artificial sweetner it contains, some of them are laxatives, particularly zorbitol ( used in sugar fee sweets and chewing gum)

ILoveToQuilt

Sorbitol, Malitol, Xylitol and any sugar which ends in "tol" can and will cause diarrhea. The "tol" sugars are laxatives (Miralax is one of the "tol" laxatives) and excess consumption can cause problems. If you must drink sugar free, try the mixes with Splenda - they are easier on the digestive system. Better still, make your own ice tea and sweeten with agave, honey or whatever pleases you. I make 1/2 gal pitcher of tea every other day. Fill pitcher with hottest tap water, put in 10 tea bags (any brand works - flavored, decaf, regular) and put in fridge. Let sit until tea cools and is the color you like. Much cheaper and tastes better than the powdered teas. If you live in a sunny area (didn't check where you are from), you can fill your pitcher (use a clear one) with water, add tea bags and set outside - sun tea.

See if making and sweetening your own tea makes a difference.