Let me preface this by saying I never drink coffee and rarely drink caffeinated soda or tea, so I am probably more sensitive to No-Doz than the average person. That said:
Finals week during the 1st semester of my senior year in college. I had 2 papers left to write (one 10-page, one 15-page), due the next day at 5 pm. I had the (I thought not unreasonable) idea of staying up all night to write them and I knew that I would need some chemical aid to support my sleep deprivation. The directions on the No-Doz box, IIRC, said to take 1-2 tablets every 4 hours. I took one tablet around 6 pm, and I drank it down with some Diet Coke. Wrote some paper. Felt sleepy around 10 pm, so I took another tablet and some more Diet Coke. (I’m saying this so you know that I had followed the directions.) By 11:30 I was as sick as a dog.
I have never felt so horrible in my whole life, including the time I had dysentery. For about 36 hours after that second No-Doz tablet, I was extremely nauseated and dizzy, to the degree that my stomach would heave with any movement I made.
I dragged myself down the stairs and forced myself to refrain from throwing up till I was in the bathroom. Vomiting didn’t alleviate my nausea/dizziness by much at all, but I believed that I just hadn’t thrown up enough, so I made myself throw up at least 20 more times that night, because, dammit, throwing up is supposed to make you feel better and I was going to feel better!
In short: my stomach was rotten, I could barely breathe, my heart was racing for hours, my face and throat felt tight and pressurized (like they were about to burst), I had trouble thinking clearly, and I just wanted to die.
I could finally walk by the next evening. Sudden movements made my head swim for a few days afterwards. Now, a couple years later, my heart beats irregularly a couple times a day and I can’t take an Excedrin without my heart racing and my limbs trembling.
Evil stuff, No-Doz.