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.

3 min read Updated Jun 2026 Read by 13,355 people
Taking Amoxicillin With Robitussin
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Simon23 asked

Is it safe to take amoxicillin with Robitussin?

Nov 08, 2022
The quick answer
  • Amoxicillin and all Robitussin brand products are safe to take together with no drug interactions.
  • You should begin to feel better within a few days of starting amoxicillin, and if your symptoms get worse or persist you should check with your doctor about other treatment options.
  • Amoxicillin should not be taken if you have a penicillin allergy.
A quick summary of Dr. Brian Staiger, PharmD's full answer below, condensed by AI from that answer only (not from any outside source). The pharmacist's answer is the source of record.

Answer

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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References & sources
  1. Amoxicillin Monograph — PubChem
  2. Common harms from amoxicillin: a systematic review and meta-analysis of randomized placebo-controlled trials for any indication — https://pubmed.ncbi.nlm.nih.gov/25404399/
  3. Acetaminophen Monograph — PubChem
  4. Dextromethorphan Monograph — PubChem
  5. Phenylephrine Monograph — PubChem
Glossary — Terms in This Answer
Beta-lactam antibiotic
A class of antibiotics that work by breaking down bacterial cell walls, commonly used to treat infections.
Penicillin allergy
An adverse immune reaction to penicillin-type antibiotics that can cause rash, swelling, or more severe reactions.
GI tract
The gastrointestinal tract, which includes the stomach and intestines where food is digested and absorbed.
Half-life
The amount of time it takes for the body to eliminate half of a drug's dose.
Analgesic
A medication that relieves pain.
Cough suppressant
A medication that reduces the urge to cough.
Cough expectorant
A medication that helps thin and loosen mucus so it can be coughed up more easily.
Decongestant
A medication that reduces nasal congestion and swelling in the airways.
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Dr. Brian Staiger, PharmD
About the pharmacist

Dr. Brian Staiger, PharmD

Clinical Pharmacy

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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