That’s a great question! I think they’re both important, but in different ways – and depending on what kind of doctor you think you might want to be?
People who are good at chemistry can be very good at making different sorts of medicines – since most of our medicines are just combinations of different kinds of chemicals. And people who are good at physics can be good at making medical devices – things like pacemakers, for example.
Biology is important too – because thats the subject where you learn all about different sorts of living animals, and how they work – things like circulation and breathing are the types of things you’d be learning about in biology that are important to becoming a doctor.
In university, you do a good mix of all of these subjects. You also do subjects like Medical Ethics, which is where you learn how to be an honest, fair doctor. All of these things come together to make a good doctor!
this really depends on what type of doctor you might want to be. Doctors who work with radiation therapy for cancers, x-rays, MRI scanners and need to know some physics to help them work out what the safe doses are. Similary, doctors who administer lots of drugs to patients and/or monitor their blood for toxins etc… will need to know some chemistry, and more specifically quite a bit of biochemistry. All of them will need to know lots of biology though.
Medicine is such a varied profession, with so many different types of work you could actually end up doing, from surgery, to x-ray imaging, to psychiatry or GP work. If you are thinking about medicine, I wouldnt worry too much about choosing between physics and chemistry at this stage, as you can always learn what you need again in the future. Alternatively you could study both in school!
I would go for chemistry over physics although biology would be the most important science for doctors. Physics are useful too for many medical professionals such as radiographers. In fact the first degree for many radiographers is physics.