Many pills, particularly capsules, are not kosher. Being that you take pills for their chemical effect as opposed to its nutrition, taking them is not a problem halachicly, as it is not “derech achila.”
Kabbalisticly, there are those that say that “timtum” may occur regardless.
Vitamins and flavored coatings are both shailos, as they each have aspects of “derech achila”.
The above opinion is for reference only, based upon information and belief.
Always ask a competent rabbi for halachik questions.
For kabbalistic questions, perhaps you can try the “goral hagra”. I definitely can’t help in that regard.