NyQuil typically takes about 30 minutes to start working after administration. Depending on individual factors like metabolism and dosage form (liquid or capsule), some people might feel its effects in as little as 15 minutes. The medication provides symptom relief that can last around 6 hours, with the drowsiness-causing antihistamine ingredient lasting up to 8 hours. Because it causes drowsiness, it is often recommended to take NyQuil about 30 minutes before bedtime so the medication can start working as you fall asleep.
