HL chemistry isn't too different from AL chemistry, which I took. I wasn't fond of it at all. Unless you're passionate about the subject and intend to greatly apply yourself, or you have an aptitude for it, you will likely find this subject rather difficult. I achieved a B (i.e. a grade 5 in the IBDP) in the end, but I required a lot of assistance and time to do so. It is slightly rewarding when I think about it, but a small part of me does sometimes ask myself whether it was truly worth it. I learnt a valuable lesson from that experience: you should take a subject because you want to, not because you other people will be pleased with your decision. If you heed this advice, you'll probably thank yourself a few years down the line.
I knew an IB pupil who is now studying medicine at Leeds, and they struggled to achieve her 6 in HL chemistry. It seemed like they had quite a stressful time.
You should also remember that medical schools are competitive, and their degrees are very challenging. It takes so many years of gruelling lucubration to become a medical practitioner. Do you think you could withstand the constant, intense pressure for that long?
From my experience, it's better to do something you love.