Can You Take Allergy Medicine and Dayquil? Generally, the answer is maybe, but it’s crucial to proceed with caution and consult with a healthcare professional or pharmacist first to avoid potential adverse interactions. Mixing allergy medicine and Dayquil can be safe for some individuals under specific circumstances, but it is essential to understand the ingredients in each medication to. View drug interactions between Allegra and Vicks Dayquil Cold & Flu Symptom Relief Plus Vitamin C. These medicines may also interact with certain foods or diseases. DayQuil is a combination cold medicine that may contain acetaminophen, dextromethorphan, and phenylephrine. Allegra (fexofenadine) is an antihistamine for allergies. Generally, these medications can be taken together safely as they work differently and have minimal interaction. Use WebMD’s Drug Interaction Checker to identify potential interactions between medications, supplements, and foods. Reduce side effects and support safer treatment decisions. Allegra is an antihistamine used to relieve allergy symptoms. Learn what medications and foods to avoid while taking Allegra to prevent adverse interactions. A member asked: Is it possible for me to take allegra (fexofenadine) 24 hours and dayquil for the flu? A doctor has provided 1 answer Combining DayQuil and Allegra-D can be safe if dosages are followed, but watch for overlapping ingredients and side effects. Many over-the-counter medicines have similar active ingredients. We asked a doctor if you can take allergy medicine with cold medicine without risks. The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine. For oral dosage form (extended-release tablets [12 hour]): For symptoms of hay. Find out if it is safe to take DayQuil and Allegra together. Learn about potential drug interactions, active ingredients, and precautions for safe combined use.