I am having a high fever with an elevated heart rate of 120-130bpm, during which i had 3 episodes of sudden spike of hr to 190-200 for a few minutes along with palpitations, dimmed vision and fainting spells. is this a normal reaction to high fever?

Your symptoms could be related to whatever is causing the fever-this could be due to an infection caused by bacteria or a virus. If your symptoms continue, you need to be evaluated by a doctor. Going to an emergency room may be your best bet to find out what is wrong and get the proper treatment after a thorough evaluation. It is not possible to make a diagnosis without an evaluation. Good luck!

I agree with Dr. F's advice. Heart rates up to 200/min for a few minutes is not simple sinus tachycardia with rates of 120 or less provoked by high fever. In addition spells of dimmed vision & fainting are very worrisome. These symptoms plus bursts of tachycardia up to rates of 200, which could be a dangerous cardiac arrhythmia, warrant prompt evaluation which is only available in the ER.