You do not need to declare preventative medications , unless linked to a pre-existing condition.
Example: If you are taking statins control previous high cholesterol or blood thinners to control previous high blood pressure we would consider this treatment of a pre-existing medical condition and you’d need to declare this. If you are however taking statins to proactively reduce your risk of high cholesterol (but havn’t had a previous high cholesterol reading) then you don’t need to declare this.