Lemonade is generally not diarrhea, but drinking ice lemonade or drinking too much of it may cause diarrhea.
Lemonade is a more common drink, lemon and drinking water as raw materials made of lemon, because lemon is rich in vitamins, can prevent skin melanin deposition, can fight free radicals, help reduce wrinkles and scars, can inhibit the crystallization of calcium salts, to enhance immunity, etc., so drinking lemonade is generally beneficial, will not diarrhea.
However, if you drink lemonade chilled or with ice, it may irritate the mucous membrane of the digestive tract and cause diarrhea. If too much lemonade is consumed, it can affect the water-electrolyte balance of the human digestive tract, leading to diarrhea.
Drinking lemon water in moderation at room temperature is generally not diarrhea.