Taking Amoxicillin With Robitussin

There is no drug interaction between amoxicillin and Robitussin. The pharmacist discusses this and more in our latest question and answer.


Is it safe to take amoxicillin with Robitussin?

Asked by Simon23 On Nov 08, 2022

Answered by
Medical Content Reviewed By HelloPharmacist Staff

Published Nov 08, 2022
Last updated Apr 19, 2024

Key points

  • There is no known drug interaction between amoxicillin and Robitussin brand products.


There are no drug interactions between Amoxil (amoxicillin) and Robitussin (guaifenesin). They are safe to take together.

Amoxicillin is actually safe to take with any Robitussin brand product, which includes:

  • Robitussin (guaifenesin)
  • Robitussin DM (guaifenesin; dextromethorphan)
  • Robitussin CF (guaifenesin; dextromethorphan; phenylephrine)
  • Robitussin Severe Multi-Symptom Cough Cold + Flu (acetaminophen; guaifenesin; dextromethorphan; phenylephrine)

It is important to be aware that worsening symptoms could be a sign that the antibiotic is not working. For most, you should begin to feel better a few days after starting the antibiotic. It may be necessary to check with your physician about other treatment options if your symptoms persist.

In the next sections, I provide more details on the drugs in question, amoxicillin, and Robitussin.

Amoxicillin Info

Amoxicillin is a beta-lactam antibiotic that is used for the treatment of respiratory, sinus, and ear infections, among others. Because amoxicillin is a type of penicillin, it should not be taken in patients with a penicillin allergy.

Reported allergies to penicillins are thought to be higher than the rate of true penicillin allergies. It is important to let your doctor and pharmacist know about your allergies or other adverse reactions before taking any medication.

Amoxicillin is well absorbed in the GI tract and is metabolized and eliminated primarily through the kidney. It is generally well tolerated but can cause rash, nausea, vomiting, and diarrhea. Taking with food can help to reduce GI symptoms.

In healthy individuals, amoxicillin has a half-life of around 1-2 hours, meaning the drug should be completely cleared within 12 hours. In those with reduced kidney function, the half-life may be significantly increased up to 13 hours (could take several days to be completely cleared).

Robitussin Info

Robitussin is a brand-name product that comes in a variety of formulations and contains several different ingredients. For example, Robitussin Cough, Cold, and Flu contains the following:

  • Acetaminophen (pain relief, fever reducer)
  • Dextromethorphan (cough suppressant)
  • Guaifenesin (cough expectorant)
  • Phenylephrine (decongestant)

Acetaminophen is an analgesic that can be taken for a wide variety of acute and chronic pain ailments. It works quickly after taking a dose, and reaches peak concentrations within 30-60 minutes. Typically, acetaminophen will 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 a bothersome dry cough or a cough that doesn’t involve mucus from the lower respiratory system.

Guaifenesin is a cough expectorant that helps break down mucus in the upper and lower airway. Guaifenesin loosens phlegm and secretions which can then be expelled. Guaifenesin is best used to reduce the symptoms of having a deep cough that can’t be cleared.

Phenylephrine is an over-the-counter decongestant. It is generally not considered as potent as pseudoephedrine, which is stored behind the pharmacy counter due to abuse potential.

Final Words

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About the Pharmacist

Dr. Brian Staiger, PharmD

Dr. Brian has been practicing pharmacy for over 13 years and has wide-ranging experiences in many different areas of the profession. From retail, clinical, program development, and administrative responsibilities, he's your knowledgeable and go-to source for all your pharmacy and medication-related questions! Dr. Brian Staiger also has herbalist training and educational certificates in the field of medical ethnobotany. Feel free to send him an email at [email protected]! You can also connect with Dr. Brian Staiger on LinkedIn.

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