Because melatonin is metabolized primarily by CYP1A enzymes, it may interact with drugs that are also metabolized by or inhibit CYP1A.
CYP1A inhibitors include estrogens in the form of contraceptives and hormone replacement therapy (HER) or the antidepressant fluvoxamine. Simultaneous use of melatonin with CYP1A inhibitors results in melatonin excess. Nicotine abuse, in turn, reduces melatonin levels.
