Prescribed Macrobid for possible UTI, took 1-100mg capsule at 11:30pm and by 7:00am I was in a panic attack, unable to breathe, chest feels like elephant is sitting on it, breathing shallow because deep breathes cause a dry, distressful cough. Very thirsty and mouth is dry. Fatigued beyond belief, chills, no temp, disoriented, hard to vocalize. My hypertension is non-existent because BP is 117/68. I ve never seen those numbers in my life. Pulse Ox is 96%. I m sure ER will just be uncomfortable, long and expensive with ABSOLUTELY NO RESULTS AS USUAL. It would be a waste of time to go unless I m not breathing. How long can I expect these symptoms to last and how much liquid Benadryl can I take safely, to see if that will help?