According to the product label on Drugs.com, four doses, which is 60 milliliters of liquid or four softgel capsules, is the daily maximum for Vick's DayQuil multi-symptom cold-flu relief. DayQuil is typically used for common cold and flu symptoms and is for temporary relief only.
The product label on Drugs.com warns that the drug should not be taken along with MAOI inhibitors and similar drugs. The drug is not for children under the age of 12.
Acetaminophen in large doses can severely affect the liver, and the drug should not be taken for more than three consecutive days, warns WebMD. Dosage must be further reduced if the patient consumes alcohol.