This combination medication is used to temporarily treat symptoms caused by the common cold, flu, allergies, or other breathing illnesses (such as sinusitis, bronchitis). Dextromethorphan is a cough suppressant that affects a certain part of the brain, reducing the urge to cough.

Perfect for people who have high blood pressure. Relieves cold & flu symptoms, including cough due to minor throat and bronchial irritation, sore throat, headache, minor aches & pains, and fever, helping you get your power back.

While NyQuil doesn't contain any decongestants, their cold and flu products include an antihistamine called doxylamine succinate and a cough suppressant called dextromethorphan. While cough suppressants won't typically affect your blood pressure, an antihistamine can.

Adults & children 12 yrs & over: 30 mL every 4 hrs. Children 4 to under 12 yrs: ask a doctor. Children under 4 yrs: do not use.

NyQuil can cause you to feel very drowsy or sleepy and you may fall asleep after taking it. Be careful when driving or operating machinery if you have taken this product. Avoid drinking alcoholic beverages with NyQuil. Alcohol, sedatives and tranquilizers can increase drowsiness when used with NyQuil.

How long does Nyquil's drowsiness last? Nyquil's active ingredient, doxylamine, which has antihistamine and sedating effects, can lead to sleepiness. Nyquil can cause different degrees of sleepiness, depending on the individual lasting anywhere from 4 to 6 hours on average.

NyQuil can cause you to feel very drowsy or sleepy and you may fall asleep after taking it. Be careful when driving or operating machinery if you have taken this product. Avoid drinking alcoholic beverages with NyQuil. Alcohol, sedatives and tranquilizers can increase drowsiness when used with NyQuil.

Don't Mix Decongestants and Blood Pressure Medication.

If you suffer from cold, cough or flu symptoms, try Coricidin HBP products. Topical nasal decongestants such as Afrin (oxymetazoline), Neo-Synephrine (phenylephrine), Privine (naphazoline), and Vicks VapoRub Inhaler (l-desoxyephedrine/levmetamfetamine) can also cause an increase in blood pressure.

Taking NyQuil can make people drowsy and fall asleep, which is the major side effect of the drug. The duration and quality of sleep can vary depending on the person. Other, rarer, side effects are mainly due to the acetaminophen component and can include: Skin reddening.

NyQuil usually triggers sleepiness approximately half an hour after a person takes the medication. Doctors may recommend waiting to take the medication until just before bedtime.

How long does Nyquil's drowsiness last? Nyquil's active ingredient, doxylamine, which has antihistamine and sedating effects, can lead to sleepiness. Nyquil can cause different degrees of sleepiness, depending on the individual lasting anywhere from 4 to 6 hours on average.