Is NyQuil (Or DayQuil) Safe To Take With Paxlovid?

Answer

You certainly are correct that Paxlovid (nirmatrelvir; ritonavir tablets) has its fair share of drug interactions but it is generally considered safe to take with both NyQuil and DayQuil

Why Does Paxlovid Have So Many Drug Interactions?

One component of Paxlovid, ritonavir, is a strong CYP3A4 inhibitor, which is an enzyme that plays a crucial role in breaking down many different medications in our body.

A CYP3A4 inhibitor, like ritonavir, can slow down or prevent the action of CYP3A4, which can cause the drugs to stay in our system for longer periods of time than they are supposed to. This can greatly increase the risk of side effects or toxicity.

CYP3A4 is responsible for breaking down around 50% of all drugs on the market, so it's a very important enzyme to consider in regard to potential drug interactions.

NyQuil & DayQuil Information

DayQuil and NyQuil are over-the-counter cold and flu medications that are multi-drug products (i.e., they contain multiple drugs). Both are used to relieve symptoms such as cough, congestion, fever, and sore throat.

DayQuil is typically used during the daytime as it does not cause drowsiness, while NyQuil is intended for nighttime use as it contains ingredients that can help induce sleep.

DayQuil contains:

• Acetaminophen (analgesic)
• Dextromethorphan (cough suppressant)
• Phenylephrine (nasal decongestant)

DayQuil Severe contains all the ingredients in 'original' DayQuil and also adds in the expectorant guaifenesin (the active ingredient in Mucinex).

NyQuil is similar to DayQuil, as it is intended for use as a cough/cold medication. However, it contains a sedating antihistamine to help individuals sleep at night.

NyQuil contains:

• Acetaminophen (analgesic)
• Dextromethorphan (cough suppressant)
• Doxylamine (sedating antihistamine)

NyQuil Severe contains all the ingredients in 'original' NyQuil and also adds in the nasal decongestant phenylephrine.

Paxlovid Is Not Known To Significantly Interact With Any Of The Drugs Contained In DayQuil Or NyQuil

Since the drugs present in NyQuil and DayQuil are not metabolized primarily by CYP3A4, the enzyme inhibited by ritonavir in Paxlovid, there is no known significant interaction expected between the two, and neither of them is known to affect the absorption of the other. They are generally considered safe to take together.

It is important to note that ritonavir (again, a component of Paxlovid), is a minor inhibitor of another enzyme, CYP2D6, which is responsible for metabolizing the cough suppressant in NyQuil & DayQuil, dextromethorphan.

However, most studies note that the inhibition of CYP2D6 is weak, and any alteration to dextromethorphan metabolism is likely to be clinically insignificant. Nevertheless, this is why you may see an interaction come up with an online drug interaction checker.

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