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( Glyceryl Guaiacolate )

Pronunciation: GWHY-fen-ah-sin
Class: Expectorant

Trade Names

- Tablets 400 mg

- Tablets 400 mg

Buckley's Cough
- Liquid 100 mg per 5 mL

DayQuil Mucus Control
- Liquid 66.7 mg per 5 mL

Diabetic Tussin
- Liquid 100 mg per 5 mL

Diabetic Tussin EX
- Liquid 100 mg per 5 mL

Diabetic Tussin Mucus Relief
- Tablets 400 mg
- Liquid 200 mg per 5 mL

Fenesin IR
- Tablets 400 mg

- Syrup 100 mg per 5 mL

- Tablets 400 mg

- Tablets, extended-release 600 mg

Mucinex for Kids
- Granules 50 mg
- Granules 100 mg
- Liquid 100 mg per 5 mL

Mucinex Maximum Strength
- Tablets, extended-release 1,200 mg

Mucus Relief
- Tablets 400 mg

Organidin NR
- Tablets 200 mg

Robitussin Chest Congestion
- Syrup 100 mg per 5 mL

Scot-tussin Expectorant
- Syrup 100 mg per 5 mL

Siltussin SA
- Syrup 100 mg per 5 mL

- Syrup 100 mg per 5 mL

Vicks Casero
- Liquid 100 mg per 6.25 mL

- Tablets 400 mg

Balminil Expectorant (Canada)
Robitussin Extra Strength (Canada)


May enhance output of respiratory tract fluid by reducing adhesiveness and surface tension, thus facilitating removal of viscous mucus and making nonproductive coughs more productive and less frequent. Efficacy not well documented.



Readily absorbed.


The half-life is 1 h; renal excretion; major urinary metabolite is beta-2-(methoxyphenoxy) lactic acid

Indications and Usage

Temporary relief of cough associated with respiratory tract infections and related conditions, such as sinusitis, pharyngitis, bronchitis, and asthma, when these conditions are complicated by tenacious mucus or mucus plugs and congestion; effective for productive as well as nonproductive cough, particularly, dry, nonproductive cough that tends to injure mucous membranes of the air passages; helps loosen phlegm and thin bronchial secretions in patients with stable chronic bronchitis.


Hypersensitivity to guaifenesin.

Dosage and Administration

Immediate-release tablets, liquid, and syrup
Adults and Children (12 y and older)

PO 200 to 400 mg every 4 h (max, 2.4 g/day).

Children 6 y to younger than 12 y

PO 100 to 200 mg every 4 h (max, 1.2 g/day).

Children 2 y to younger than 6 y

PO 50 to 100 mg every 4 h (max, 600 mg/day).

Children 6 mo to younger than 2 y

PO Individualize dose, 25 to 50 mg every 4 h (max, 300 mg/day).

Extended-release tablets
Adults and Children 12 y and older

PO 600 mg to 1.2 g every 12 h (max, 2.4 g/day).

General Advice

  • Have patient swallow whole with a full glass of water. Caution patient not to chew, crush, or break the ER tablet.
  • Administer without regard to meals, but administer with food if GI upset occurs.
  • Measure and administer liquid or syrup dose using dosing spoon, syringe, or cup.
  • For granules, empty entire contents of packet onto tongue and swallow. For best taste, do not chew.


  • Store liquid, syrup, and immediate-release tablets between 59° and 86°F.
  • Store ER tablets between 68° and 77°F.
  • Protect from light. Protect tablets from moisture.

Drug Interactions

None well documented.

Laboratory Test Interactions

Guaifenesin may increase renal Cl for urate, which may lower serum uric acid levels; may produce an increase in urinary 5-hyroxyindoleacetic acid, which may interfere with interpretation of this test for diagnosis of carcinoid syndrome; may falsely elevate vanillymandelic acid in certain serotonin metabolite chemical tests because of color interference.

Adverse Reactions


Dizziness, headache.


Rash, urticaria.


GI discomfort, nausea, vomiting.



Category C .




Safety and efficacy of ER tablets not established in children younger then 12 y. The 400 mg tablets are not recommended in children younger than 6 y.

Kidney stone formation

Large quantities of guaifenesin-containing medications may be associated with an increased risk of drug-induced kidney stone formation.

Persistent cough

May indicate serious condition. Notify health care provider if cough persists for more than 1 wk, tends to recur, or is accompanied by high fever, rash, or persistent headache.

Patient Information

  • Explain that expectorants are not usually used for chronic cough conditions such as those caused by smoking, asthma, chronic bronchitis, or emphysema, or when cough is accompanied by excessive secretions.
  • Explain importance of maintaining increased fluid intake to help thin bronchial secretions.
  • Advise patient using syrup, liquid, or immediate-release tablets to take prescribed dose every 4 h as needed, up to 6 times per day.
  • Advise caregiver to use dosing spoon, syringe, or cup when giving liquid or syrup to children.
  • Advise patient using ER tablets to take every 12 h as needed, up to 2 times per day. Caution patient to swallow tablets whole with a full glass of water and not to chew, crush, or break the tablet.
  • Advise patient or caregiver that medication can be taken without regard to meals, but to take with food if stomach upset occurs.
  • Advise patient that if a dose is missed, to take as soon as remembered unless it is nearing time for the next dose, in which case the dose should be skipped and the next dose taken at the regularly scheduled time. Caution patient not to double the dose to catch up.
  • Advise patient that if cough is not controlled, not to increase the dose of medication but to inform a health care provider.
  • Instruct patient to inform health care provider if any of the following occur: cough persists for more than 1 wk; cough keeps coming back; cough is accompanied by high fever, skin rash, or headache.

Copyright © 2009 Wolters Kluwer Health.