The main active ingredients in Dayquil are acetaminophen and dextromethorphan HBr. The acetaminophen is used to relieve pain and reduce fever, and the dextromethorphan HBr is used to suppress coughing.
DayQuil also contains purified water, sodium chloride, citric acid, yellow dye number 6, and sorbitol. Vicks recommends that no more than four doses be taken in a 24-hour period, and the dosage amount varies based on age. For example, individuals ages 12 and up can take up to 2 tablespoons every 4 hours. DayQuil should not be given to any child under the age of four.