What Are The Risks While Taking Effexor And NyQuil Together?

I take 375 mg of Effexor daily, three .75 mg in the morning and two at night. I have a bad head cold and would like to take Nyquil tonight to sleep and clear my head. How great a risk would that be to combine the two? I read all the possible consequences, but also read that the worst side effects are rare. Would it amount to Russian roulette to take the Nyquil? I took the Effexor about four hours ago. Please advise. Thank you.