Overview

There are no drug interactions between benzonatate (Tessalon Perles) and acetaminophen, dextromethorphan, and doxylamine ( the active ingredients in Nyquil).

One thing that could be of theoretical concern is drowsiness. Both benzonatate and Nyquil may cause drowsiness, although are generally well tolerated by most people.


Tessalon Perles Info

Benzonatate is a non-opioid cough suppressant that essentially numbs the cough reflex.

Benzonatate is similar in structure to anesthetics like tetracaine. Typically, this medication will start to work in about 15-20 minutes and lasts up to 8 hours.

The brand name for benzonatate, Tessalon Perles, makes sense when noticing its resemblance to a pearl. Benzonatate is well-tolerated but may cause an allergic reaction, drowsiness, dizziness, and headache.


NyQuil Info

Nyquil comes in a variety of formulations and contains several different ingredients. Nyquil Cold & Flu contains the following:

  • Acetaminophen (pain relief, fever reducer
  • Dextromethorphan (cough suppressant)
  • Doxylamine (antihistamine)

Acetaminophen is an analgesic that can be taken for a wide variety of acute and chronic pain ailments. Acetaminophen has a half-life of 2-3 hours.

Acetaminophen gets absorbed at 85-98% and reaches peak concentrations within 30-60 minutes.

Typically, acetaminophen can start working within 15 minutes. Acetaminophen can have negative impacts on the liver, especially at higher doses for an extended period of time.

Dextromethorphan (commonly referred to as DM on many over-the-counter products) is a cough suppressant that reduces the urge to cough. It is best to prevent bothersome dry cough or a cough that doesn’t involve mucus from the lower respiratory system.

Doxylamine is a first-generation antihistamine that is more likely to cause sedation and drowsiness as compared to second-generation antihistamines (i.e. loratadine, cetirizine).

Other first-generation antihistamines include Benadryl (diphenhydramine), Dramamine (dimenhydrinate), Chlor-Trimeton (chlorpheniramine), Tavist (clemastine), and Phenergan (promethazine), among others.


Summary

  • Since both NyQuil with benzonatate cause sedation, taking both together can increase this effect.

  • References
    1. Tessalon Prescribing Information. AccessFDA
    2. NyQuil Monograph: ClinicalKey. ClinicalKey