Do antihistamines cause kidney stones?

Unlikely: I have never seen or read about this being a problem. I guess theoretically if you were one who gets very 'dried out' with antihistamines it might be a concern, but i think that is unlikely.

No: Antihistamines have not been shown to cause kidney stones.

Longshot, but...: Maybe. I treated one patient, during my residency, who had stones composed of crystallized Guaifenesin (a cough suppressant). There are scattered case reports describing this in people who overuse these types of medications. The reason this might be relavent is many otc cough and cold remedies contain antihistamines, but may also contain guaifenesin. It's a longshot!