Does Robitussin Ac (guaifenesin with codeine) cause side effects?

Robitussin Ac (guaifenesin with codeine) is a combination of an expectorant and a narcotic cough suppressant used to treat cough caused by conditions such as the flu, cold, bronchitis, or sinusitis.

Guaifenesin which works by thinning and increasing the volume of mucus. Codeine works by suppressing the cough reflex in the brain, eventually reducing the frequency of cough.

Common side effects of Robitussin Ac include

Serious side effects of Robitussin Ac include

Drug interactions of Robitussin Ac include naltrexone, which decreases the effect of codeine in the body, therefore codeine must not be used with naltrexone. Any other medications that increase drowsiness should be used with caution with Robitussin Ac.

There are no adequate studies with Robitussin Ac to determine its safety and effectiveness in pregnant women.

Robitussin Ac is excreted in breast milk and could have undesirable effects on a nursing infant. It must be used with caution in nursing mothers. Consult your doctor before breastfeeding.

What are the important side effects of Robitussin Ac (guaifenesin with codeine)?

Side effects of guaifenesin are uncommon, but can include:

Robitussin Ac (guaifenesin with codeine) side effects list for healthcare professionals

No information provided.

What drugs interact with Robitussin Ac (guaifenesin with codeine)?

Caution should be used when taking this product with sedatives, tranquilizers and drugs used for depression, especially monoamine oxidase inhibitors (MAOIs). These combinations may cause greater sedation (drowsiness) than is caused by the products used alone.


Take orally as stated below or use as directed by a doctor.

  • Adults and children 12 years of age and over: 2 teaspoonfuls every 4 hours, not to exceed 12 teaspoonfuls in a 24-hour period;
  • Children 6 to under 12 years: 1 teaspoonful every 4 hours, not to exceed 6 teaspoonfuls in a 24-hour period;
  • Children under 6 years: consult a doctor.

A special measuring device should be used to give an accurate dose of this product to children under 6 years of age. Giving a higher dose than recommended by a doctor could result in serious side effects for a child. Use of codeine-containing preparations is not recommended for children under 2 years of age. Do not exceed recommended dosage.

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Medically Reviewed on 10/23/2020
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Professional side effects and drug interactions sections courtesy of the U.S. Food and Drug Administration.