Guaifenesin (OTC)


Benylin-E, Humibid, Organidin NR, Robitussin, Children’s Mucinex (labeled chest congestion in grape flavored)


  • Capsules: 200 mg
  • Tablets: 100 mg
  • Syrup: 100 mg/5mL


Guaifenesin is an expectorant. It increases respiratory tract fluid by reducing adhesiveness and surface tension. This in turn helps to thin the mucus making it easier to cough up and remove from the airways. It also acts as a skeletal muscle relaxant, but the exact mechanism of this action is unknown. Guaifenesin has minimal effects on diaphragmatic function, and produces very little respiratory depression at therapeutic doses.

Guaifenesin is conjugated in the liver and excreted into the urine. It is reported to cross placental barrier; however adverse effects in newborns have not been documented at this time. No studies at present have been done in rats to indicate if guaifenesin is passed in breast milk.


Used for relief in bronchitis and respiratory infections where a dry, nonproductive, cough is present. In rats only as directed for tenacious thick mucus.

Drug Interactions or Contraindications

  • Contraindicated in hypersensitivity.
  • Not recommended in coughs accompanied by excessive secretions.

Adverse Reactions

CNS: drowsiness, restlessness

GI: poor appetite

Dosage Recommendations

1/10th the child’s dose (dosage in rats is empirical) 3, 12


  • Encouraging fluids, and fruit that is juicy, along with the use of a humidifier can help to liquify secretions.
  • Store at room temperature.


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