Studying medicine but I need to take chemistryWatch
Have you checked the subject requirements for Medicine at the Universities you are thinking of applying to, that might help guide your decision? As far as I know, they have made the subject requirements a lot more flexible even from this year compared to last so that might help you as they don't seem to really have firm subject requirements for Advanced Higher although I think that most universities still require you to have at least higher chemistry at some point. I know that at Glasgow they do generally require that you have 5A's in Higher by the end of S5, then at least BBB at advanced higher in S6 or AB at Advanced Higher along with a B at higher in S6. Edinburgh also require you to have 5 highers by the end of S5, so dropping Higher Modern Studies for N5 Chemistry would leave you with 4 highers by the end of S5 which would mean you wouldn't be eligible for Medicine as an undergraduate -at least if you apply to those Universities. It's worth looking into it but as far as I know you need 5 Highers by the end of S5 for all the Scottish Universities.
Generally you can crash a higher in S6 if you are applying for Medicine, the problem is I don't know if you all universities would accept if you crash Higher Chemistry in S6 given it's importance and what the universities require if that makes sense? Some universities are more flexible and might be more open to you doing Higher chemistry in S6 while others might have a problem with it, e.g. St Andrews ask for it in the same sitting as your other highers: "Highers must include Chemistry and one of Biology (or Human Biology), Mathematics or Physics, to be taken at the same sitting". Whereas Aberdeen is quite flexible, they don't seem to care if you do higher chemistry in the same year as your other highers. Also as far as I know, Glasgow would accept it if you did Higher Chemistry in S6 provided you received 5 A's in 5 Highers at S5 (though I would recommend double checking this). Edinburgh say: "SQA: Highers: Chemistry and two of Biology, Mathematics or Physics. For some applicants this subject combination is not possible at S5. Students who meet the grade requirements in S5 but are missing one or more sciences may take the missing subject(s) in S6. National 5s: Biology, Chemistry, English and Mathematics at B. "-so it seems like they would be willing to accept you doing Higher Chemistry in S6 but you have to have 5 Highers in S5, however, they do generally ask for Chemistry at Nat 5 as well so I would still contact them just for clarification. Overall it would be best to double check with the universities, there is no harm in asking. Given my situation, I was able to apply to Edinburgh without Nat 5's and was told they would adjust my score accordingly but I didn't have any Nat 5's while you are currently missing chemistry so definitely contact them if you are planning on applying there.
Maybe try the medic portal comparison tool to compare what qualifications different medical schools require:
From my own opinion and experience with applying for Medicine, I would say definitely don't drop a Higher for a Nat 5 course at S5, even Aberdeen which is quite flexible require you to have 5 highers by the end of S5. Unless you swap Higher Modern Studies for Higher Chemistry in S5, it wouldn't work, you can't drop a higher. So you could possibly keep your current subject choice and then crash Higher Chemistry in S6 (knowing that it may limit the Universities you can apply to) or if you are determined to do Nat 5 chemistry in S5, then you might have to take it as a 6th subject, if that makes sense but you need to do at least 5 highers in S5. What do you think? Which Universities do you want to apply too? It would be worth contacting them to see if you could possibly do Higher Chemistry in S6 and whether they would still happily accept that and then take things from there?
Are you thinking of applying to the Scottish Universities for Medicine? I only have knowledge of the Scottish Universities so my knowledge is only regarding those. For all the med schools, look up: Entry requirements for UK medical schools 2021 entry. You should find a pdf document that matches that name which might be helpful.
I hope this helps! Sorry if there are repetitive bits.