Avoid concomitant use w/ nasal azelastine, orphenadrine, oxomemazine, paraldehyde & thalidomide. Increased effect/toxicity of ethyl alcohol, opioid analgesics, nasal azelastine, blonanserin, buprenorphine, CNS depressants, flunitrazepam, QTc-prolonging agents (moderate & highest risk), hydrocodone, methocarbamol, methotrimeprazine, metyrosine, mirtazapine, orphenadrine, oxycodone, paraldehyde, piribedil, pramipexole, ropinirole, rotigotine, SSRIs, suvorexant, thalidomide, zolpidem. Increased levels/effects w/ topical brimonidine, cannabis, chlormethiazole, chlorphenesin carbamate, topical dimethindene, doxylamine, dronabinol, droperidol, hydroxyzine, kava kava, lofexidine, Mg sulfate, methotrimeprazine, mifepristone, minocycline, nabilone, oxomemazine, perampanel, rufinamide, Na oxybate, tapentadol, tetrahydrocannabinol, trimeprazine.