I had a cardiac CT scan with contrast dye injection. I was not aware of any serious side affects or really aware about the injection before entering the scan room. Whilst being administered the first injection I felt the very warm flush go through my entire body, then on the second injection it felt even warmer and byu the time the nurse entered the scan room my body was shaking uncontrollably. When walking from the scan room my whole body felt like lead by throat felt tight and I had the bitter taste in my mouth. Then I had swellings appear on my face and red patches on my body and under my eye and I felt very faint. I was given an high dose shot of antihistamine and also a steroid injection. I had to remain at hospital in bed for the rest of the day with regular checks on my blood pressure. They also informed me that on the 2nd shot of injection during he scan my heart rate went sky high! I drank lots of water to flush the contrast out of my system and also to cool me down and my whole head was on fire and was administered a cold compress. On leaving hospital I had a severe headache for several days after. I was told that it is very rare to have a severe reaction - but I as one of them! Thankfully I wont ever be able to have any contrast dye injections. Make sure that this appears on all your medical notes and also if you are under different hospitals and doctors that they are all aware of your severe reaction, if you are unlikely like I was.