Is it safe to take nyquil and adipex together?

Usually ok. There have been a few rare reports of symptoms of difficulty breathing, heart palpitations, sweating, and hypertension. The Phentermine in adipex can cause these symptoms, but rarely does. The nyquil can contain Pseudoephedrine and doxylamine which may make the Phentermine more likely to cause these symptoms. There don't appear to be reported deaths or long term effects, but you may be risking short.