Is it safe to discontinue prozasin "cold turkey"? Do prazosin & niacin interact?

An abrupt discontinuation of prazosin can cause a worsening of some
symptoms. Dosage, of course, makes a difference, and I am guessing
d/c-ing 1 mg abruptly is fine, but not knowing what other health issues
you may be dealing with, you should first consult your doc. Good luck

You are ok to take the prazosin and niacin. If you stop the prazosin, you may cause your blood pressure to go up. High blood pressure can be asymptomatic thus you wouldn't know it, but can be very dangerous so check your blood pressure often if you stop the medication.