。
You won't get better just by relying on medicine.
Literal
Medicine [only-だけ][obj-を] depend-make-[even-ても] not-heal [assertion-よ].
頼りにする is an idiomatic collocation — 頼り ('reliance') + にする ('make into, treat as') = 'treat as a thing one relies on,' i.e., 'rely on.' ~ても ('even if') with a negative predicate gives 'even if you do X, not Y.' The final よ adds conversational emphasis, like 'I'm telling you.'