What Are the Side Effects of NyQuil?

By Staff WriterLast Updated Apr 16, 2020 3:22:55 PM ET

Common side effects of NyQuil include constipation, appetite loss, anxiousness, stomach upset and queasiness, according to Drugs.com. Severe side effects include urinary difficulties, hives and irregular heartbeat. It is important for individuals to seek medical attention if common side effects are persistent or individuals experience any severe side effects.