Hi Renae . I take Plaq. and prendisone along with a drug for fatigue called provigil ( it's a stimulant, so of course it lowers my appetite ). I do not Know about otc diet pills, but my stimulant dosen't interact with the lupus drugs. If i need a narcodic for pain, I do have to wait at least 4 hours after taking the provigil. I'm sure that a pharmicist could fill you in on the safty of diet pills and the other meds you are on. Best wishes.