Our pharmacist answers the latest question regarding whether or not your deserve to take Benadryl (diphenhydramine) via Nyquil.

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At a glance

NyQuil includes doxylamine, a sedating first-generation antihistamine. Benadryl has diphenhydramine, additionally a sedating first-generation antihistamine. Use of both together rises the threat of side effects such as oversedation, dry mouth, dry eyes and also constipation.



In many instances, it is not recommended to take Benadryl (diphenhydramine) and also Nyquil together considering that they both contain sedating antihistamines.<1>

The sedating antihistamine in NyQuil is doxylamine, which is extremely carefully regarded diphenhydramine (the energetic ingredient in Benadryl). In fact, they are in the exact same class of medication, sedating first-generation antihistamines.

Taking two first-generation antihistamines together is taken into consideration "duplicate therapy" and also boosts the risk of side impacts arising.

What Is Benadryl?

Benadryl is classified as an initial generation antihistamine. The duration of activity of the drug is commonly 4-6 hrs per dose (25 mg to 50 mg).<2>

First generation antihistamines are recognized for their sedative effects and also CNS (central nervous system) depressant effects. Many type of individuals cannot tolerate the sedative effects of Benadryl (diphenhydramine) in the time of the day and also, therefore, only take it at bedtime to combat insomnia.

What Is NyQuil?

Nyquil is a combination cold/cough product that includes the drug doxylamine, in addition to a pain/fever reducer (acetaminophen) and a cough suppressant (dextromethorphan).

Doxylamine is a sedating first-generation antihistamine and also is in the same class of medication as Benadryl (diphenhydramine).<3>

Interaction Explained

As declared above, both doxylamine and also Benadryl (diphenhydramine) work-related the very same method and are actually in the exact same class of medication.

They occupational by blocking the histamine-1 receptor in the body, which stays clear of histamine from binding to it and creating the symptoms we are all exceptionally familiar through (e.g. runny nose, watery eyes, and so on...).

Due to the fact that both drugs work the very same method, utilizing both at the very same time is not recommended.

Combined usage mostly will not carry out any type of even more advantage than taking either alone. Furthermore, taking them together not just rises the hazard of too much sedation, it substantially increases the threat of added adverse effects such as:<4>

Dry mouthDry eyesConstipationConstricted airways

Very high doses of sedating antihistamines have actually likewise been associated via excitation, agitation, and restlessness.<5>

When Is Use With Each Other Okay?

Having sassist that, there can be a situation to take the combination together.

Benadryl (diphenhydramine) has actually fairly strong proof for usage in stemming allergic reactions.

Studies display that Benadryl (diphenhydramine) deserve to properly minimize itching and swelling from reactions to points like bee stings and also poichild ivy.

See more: Which Of The Following Best Defines Scientific Management? ?


If you have actually already taken a dose of Nyquil and also are having an allergic reaction to somepoint, taking a dose of Benadryl (diphenhydramine) may help without a substantial enhanced danger in intolerable side effects.