Firstly, it's zi, not si. Secondly, I don't know how far in the course this sentence is, there is this problem that the word "swój" (one's own) was introduced too late in the course. "Wziąłeś twoje leki" may not be incorrect, but at least weird. It should be "swoje", because it refers to the same subject (you) that's already mentioned in the sentence. Compare with "On wziął twoje leki" = "He took your meds".
Unfortunately, because of this problem with introducing 'swój' too late you've encountered many sentences that should rather use it and not simple 'mój/jego/ich etc.' But of all such usages, I personally think "twój" is the absolutely least natural and most awkward.
The first answer I wrote in English was 'you took the medicine?' I suppose it sounds ok if one was a little surprised about someone taking something for medicinal purposes. The given answer with 'Did', would be asking for confirmation. My point being that maybe it can also be correct (my first answer), as it depends on the context and situation.