It could help to temporary reduce some of your symptoms, depending on which one you have - congestion, headache, fever, etc. but does not contain the mild sleep aid that is found in NyQuil. DayQuil doesn't have stimulant to keep you awake, it just doesn't have a sleep aid.
What is DayQuil good for?
DayQuil Cold & Flu is a combination medicine used to treat headache, fever, body aches, cough, stuffy nose, and sinus congestion caused by allergies, the common cold, or the flu. This medicine will not treat a cough that is caused by smoking, asthma, or emphysema.
What does DayQuil do for you?
Dextromethorphan is a cough suppressant that affects a certain part of the brain (cough center), reducing the urge to cough. Decongestants help to relieve stuffy nose symptoms. This product also contains acetaminophen (APAP), a non-aspirin pain reliever and fever reducer.