question: Concerned our teenage daughter started this summer with when getting overheated she develope a rash.  Now instead of a rash it is itchy welts the size of a breath mint.  It only occurs when she does a physical activity or from taking hot shower. Our doctor prescribed singulair this summer which didnt work so we discontinued, now she is trying zafirlukast 20mg.  She has only been taking it for one week, but I see no difference. To be quite honest, the only thing that actually works is products like benedryl (which sometimes make her drowsy).  I did give her a generic form of antihistamine yesterday which worked well, without the drowsiness.  I would really like to know what this is and how long it will last as I really do not want her on meds.