Guaifenesin

Pronunciation: gwye-FEN-eh-sin.

Generic name
guaifenesin
Brand names
Robitussin Chesty Cough Medicine (United Kingdom)
Drug class
Expectorant
Form
Extended-release tablet or oral liquid, depending on product
Route
Oral
Legal status
Available over-the-counter in the United States and United Kingdom.

Availability and supply rules vary by country

Trade names by country: United States · Canada

Australia: · Full directory

What guaifenesin is and how it works

Guaifenesin is an expectorant that loosens phlegm (mucus) and thins bronchial secretions, making a cough more productive. (1)

It is used for a chesty cough with mucus. It is not intended for a chronic cough from smoking, asthma, chronic bronchitis, or emphysema without a doctor's input first.

Mechanism of action: how guaifenesin works

Guaifenesin increases respiratory tract fluid output and reduces the viscosity and surface tension of mucus, promoting ciliary clearance and converting an unproductive cough into a more productive, less frequent one. (1)

What guaifenesin is used for

Chesty cough with mucus

Helps loosen phlegm and thin bronchial secretions to make coughs more productive and clear the airways of bothersome mucus. (1) (2)

Before taking guaifenesin

Do not take / not appropriate for

  • Do not use in children under 12 years of age. (all products) (1) (2)

Tell your clinician about

  • A chronic cough related to smoking, asthma, chronic bronchitis, or emphysema.
  • A cough with a large amount of phlegm.
  • Whether you are taking another cough or cold medicine, since combining products is not recommended.
  • Pregnancy or breastfeeding.
(1) (2)

How to take guaifenesin

  • Take exactly as directed on the product label.
  • Extended-release tablets should be swallowed whole with a full glass of water; do not crush or chew them.
  • Do not combine with another cough or cold medicine unless a doctor or pharmacist says it is safe to do so.
(1) (2)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2)

Missed dose

Take as directed on the product label or by your doctor. Do not take a double dose; ask a pharmacist if you are unsure.

Overdose

Contact a poison control centre or emergency service immediately if an overdose is suspected, even without symptoms. (1)

Side effects

Guaifenesin is generally well tolerated; the main concern is using it appropriately for the right kind of cough.

Nausea or stomach upset

What to notice: Mild digestive discomfort has been reported with some products.

What to do: Tell your pharmacist or doctor if this is bothersome. (1)

Cough that persists or is accompanied by other symptoms

What to notice: Cough lasting more than 7 days, a cough that comes back, or a cough with fever, rash, or a persistent headache.

What to do: Stop using this product and see a doctor; these symptoms may indicate a condition that needs a different assessment or treatment. (1)

Serious warnings

Cough lasting more than 7 days or with fever, rash, or persistent headache — urgent

Symptoms: Cough that lasts more than 7 days, keeps recurring, or occurs with fever, rash, or persistent headache.

Action: Stop use and see a doctor; these can be signs of a condition needing a different assessment or treatment. (1)

Liver function changes —

Action: Seek immediate medical attention if signs of allergic reaction or liver problems occur. Contact your healthcare provider before stopping treatment.

Interactions

Medicine or testEffectAction
Other cough and cold medicinesCombining products can lead to duplicate ingredients or unexpected combined effects.Do not use with another cough or cold medicine unless a doctor or pharmacist confirms it is safe. (2)

Pregnancy, breastfeeding, kidney/liver function, age

Chronic respiratory conditions

If your cough is related to smoking, asthma, chronic bronchitis, or emphysema, or produces a large amount of phlegm, check with a doctor before use rather than self-treating. (1)

Pregnancy and breastfeeding

Ask a doctor or pharmacist before use if you are pregnant or breastfeeding. (1)

Children

Not for use in children under 12 years old. (1) (2)

Monitoring

Before starting

  • Confirm the cough is not related to a chronic respiratory condition needing separate medical assessment.
  • Check whether another cough/cold medicine is already being used.

During treatment

  • Reassess if cough lasts more than 7 days, recurs, or occurs with fever, rash, or persistent headache.
(1)

Storage

Store at controlled room temperature, out of reach of children, with the container's tamper-evident seal intact before first use.

Professional information

Clinician-facing context only. Use the current local product information for exact dosing.

United States (OTC Drug Facts label, extended-release)

Indication: Chesty cough with mucus

Dose summary: 600 mg tablets: adults and children 12+, 1-2 tablets every 12 hours, maximum 4 tablets/24h. 1200 mg tablets: 1 tablet every 12 hours, maximum 2 tablets/24h. Not for children under 12.

Renal context: No renal/hepatic-impairment-specific adjustment is described in the OTC label reviewed. (1)

United Kingdom

Indication: Chesty cough with mucus

Dose summary: Adults, the elderly, and children over 12: one 10 mL dose (100 mg/5 mL solution) up to 4 times daily. Not for children under 12.

Renal context: Not established in the source reviewed for this dossier. (2)

Mechanism of action

Hepatic guidance

Use local product information and clinical judgement; this page does not provide impairment-specific dosing.

Overdose note

Manage suspected overdose supportively per local poison-control and emergency guidance. (1)

Frequently asked questions

What is guaifenesin used for?

guaifenesin is prescribed for approved indications. Always follow your healthcare provider's guidance.

What are the side effects of guaifenesin?

Common side effects may include gastrointestinal symptoms and headache. Serious side effects require immediate medical attention.

Can I take guaifenesin with other medications?

Always inform your healthcare provider about all medications you are taking, including over-the-counter products and supplements.

What is the mechanism of action of guaifenesin?

Guaifenesin increases respiratory tract fluid output and reduces the viscosity and surface tension of mucus, promoting ciliary clearance and converting an unproductive cough into a more productive, less frequent one. (1)

What is the generic name of Guaifenesin?

The generic name is guaifenesin. It is sold under brand names including Robitussin Chesty Cough Medicine (United Kingdom). (1) (2)

What class of drug is guaifenesin?

Guaifenesin is classed as: Expectorant. (1) (2)

References

  1. GUAIFENESIN extended-release tablet — Drug Facts labelDailyMed, U.S. National Library of Medicine (OTC Drug Facts label) · United States · accessed 2026-07-26 · source 1
  2. Robitussin Chesty Cough Medicine (guaifenesin 100 mg/5 mL) -- SmPC/product summaryelectronic Medicines Compendium (UK) -- via web search summary · United Kingdom · accessed 2026-07-26 · source 2
  3. GUAIFED (GUAIFENESIN) LIQUID [ALDAMA PHARMACEUTICALS, INC] — US prescribing information (DailyMed SPL)U.S. National Library of Medicine (DailyMed) · US · accessed 2026-08-14 · source 3
  4. Guaifenesin — patient drug information (MedlinePlus)U.S. National Library of Medicine (MedlinePlus) · US · accessed 2026-08-14 · source 4
  5. Rompe Pechito DM for Kids — FDA approval record (Drugs@FDA M012)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 5
  6. guaifenesin — RxNorm normalized drug concept (RXCUI 5032)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 6

Brand names by country

Single-ingredient guaifenesin names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

United States

  • mucus400 mg, 1200 mg, 600 mg, 200 mg · pioneer life sciences, llc
  • Mucinex1200 mg, 600 mg · a-s medication solutions
  • Maximum Strength Mucus Relief1200 mg · chain drug marketing association inc
  • Chest Congestion Relief100 mg/5mL, 400 mg · rugby laboratories
  • good sense mucus er1200 mg, 600 mg · l. perrigo company
  • Giltuss EX Expectorant400 mg0mL, 600 mg · gil pharmaceutical corp
  • MUCUS RELIEF GUAIFENESIN EXTENDED-RELEASE 600 mg1200 mg, 600 mg · yyba corp
  • good neighbor pharmacy mucus er1200 mg, 400 mg · amerisource bergen
  • equate mucus-er1200 mg, 600 mg · wal-mart stores, inc.
  • DG Health Mucus ER1200 mg, 600 mg · dolgencorp inc

Canada

  • EXPECTORANT
  • ROBITUSSIN MUCUS & PHLEGM
  • BALMINIL EXPECTORANT
  • CHEST CONGESTION
  • EXPECTORANT COUGH FORMULA SYR
  • COUGH SYRUP EXPECTORANT
  • BRONCHOPHAN EXPECTORANT (SANS SUCROSE)
  • VICKS CHEST CONGESTION RELIEF
  • EXPECTORANT (REGULAR STRENGTH) COUGH
  • VICKS DAYQUIL MUCUS
View brands in additional countries.