Is it okay to take nyquil if you take nortriptyline, paxil, hydrochlorothiazide but not all at the same time?

Better avoid: You didn't mention which nyquil preparation, at any rate all contain an antihistaminic which interacts with paxil and nortriptyline, timing isn't the issue as all stay in your system for prolonged hours. You want to revise all your meds with your prescriber for dosage adjustments and monitoring as paxil nortriptyline and hdrocholrothiazide do interact, so better see your doctor, best wishes