Actually I am from family of doctors and I was also a medical student but had to quit due to my severe health issues few years back. I have studied this subject for two years. For medical students yes it is shame to study from any other book. But it is real helpful. I used to study from guyton and hall for concept building as it is very comprehensive book. But after making concept I used to make my notes on firdous physiology for cramming as it was to the point. I had notes of one of the CSP's on this topics which were downloaded by me almost one and half year ago. I will try to find the link or will upload it and share the link very soon In Sha Allah.

There is no need to study from Guyton at all as medical students study it in two years time duration . Its very lengthy and no one is gonna treat any patients and no one will expect that kind of knowledge. Firdous is best.Go for it.