Taking NyQuil With Allegra
In our latest question and answer, the pharmacist discusses whether or not NyQuil can safely be taken with the antihistamine Allegra (fexofenadine).
I take Allegra every morning for my allergies. I am wondering if it is okay to take NyQuil once in a while at night to help sleep?
May 12, 2022- Allegra and NyQuil can be taken on the same day but should be separated by at least four to six hours to reduce the risk of excess drowsiness and sedation.
- Allegra is a non-drowsy antihistamine, but NyQuil contains a sedating antihistamine, so taking them together increases the chance of side effects like drowsiness, dry mouth, and constipation.
- A safe approach is to take Allegra in the morning for allergies and NyQuil in the evening for cough and cold symptoms.
Overview
In the vast majority of individuals, it is safe to take Allegra (fexofenadine) the same day as NyQuil, even though Allegra is an antihistamine and NyQuil contains an antihistamine.
However, they generally should not be taken at the same time.
At the very least, they should be separated from one another by at least four to six hours to decrease the risk of excess sedation and drowsiness.
Allegra is essentially non-drowsy on its own, but it is a general rule of thumb to not combine two drugs in the same medication class (unless otherwise directed to do so by your doctor).
Interaction Details
Allegra (fexofenadine) is a "second generation" antihistamine and has a duration of action of around 24 hours.
Most second-generation antihistamines do not cause drowsiness or sedation, including Allegra.
While Allegra doesn't cause drowsiness on its own, it can still increase the risk of sedation when used with other sedating medications.
NyQuil is a combination ingredient cough/cold medication and contains the following active ingredients:
- Acetaminophen (analgesic)
- Dextromethorphan (cough suppressant)
- Doxylamine (sedating antihistamine)
Doxylamine, like Allegra, is an antihistamine but is classified as a "first-generation" antihistamine.
First-generation antihistamines are characterized by their short duration of action (~4 to 6 hours) and their sedative effects.
While doxylamine is effective for the treatment of allergy symptoms, it is most often used in over-the-counter products as a sleep aid.
The concern with using NyQuil and Allegra at the same time is the potential for additive antihistamine side effects from each, which potentially includes:
- Drowsiness
- Constipation
- Dry mouth
- Dry eyes
- Sedation
Final Words
Summing things up, as mentioned, Allegra should not be taken at the same time as NyQuil due to the additive sedative effects.
However, if you take Allegra in the morning for your allergy symptoms and you tolerate it well, you can certainly take NyQuil safely in the evening to help with cough/cold symptoms and for problems falling asleep.
Glossary — Terms in This Answer
- Antihistamine
- A medication that blocks histamine, a chemical in the body that causes allergy symptoms like itching and sneezing.
- Second generation antihistamine
- A newer type of antihistamine that is designed to treat allergies without causing drowsiness.
- First-generation antihistamine
- An older type of antihistamine that effectively treats allergies but commonly causes drowsiness as a side effect.
- Duration of action
- The length of time a medication remains active and effective in your body.
- Sedating
- Causing or tending to cause calmness, relaxation, or sleep.
- Dextromethorphan
- An active ingredient used in cough medicines to suppress coughing.
- Doxylamine
- A sedating antihistamine commonly used as a sleep aid in over-the-counter cold and flu medicines.
- Additive effects
- When two medications combine to produce a stronger effect than either would cause alone.
Dr. Brian Staiger, PharmD
Doctor of Pharmacy, board certified clinical pharmacist (BCPS), American Herbalist Guild, Medication Therapy Management certified
Brian Staiger, PharmD, BCPS, is a licensed pharmacist with more than 13 years of experience across retail pharmacy, clinical pharmacy, medication safety, pharmacy program development, and healthcare administration. He is the founder of HelloPharmacist.com, where he helps patients...
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