From WikiProjectMed
Jump to navigation Jump to search
Trade namesMucinex, others
Other namesGlyceryl guaiacolate
  • (RS)-3-(2-methoxyphenoxy)propane-1,2-diol
Clinical data
Main usesPhlegm in the airway[1]
Side effectsDizziness, sleepiness, skin rash, nausea[2]
  • US: C (Risk not ruled out)
Routes of
By mouth (tablets, syrup)
Defined daily dose900 mg[3]
External links
License data
Legal status
  • US: OTC / Rx-only
Elimination half-life1–5 hours[4]
Chemical and physical data
Molar mass198.218 g·mol−1
3D model (JSmol)
ChiralityRacemic mixture
  • O(c1ccccc1OC)CC(O)CO
  • InChI=1S/C10H14O4/c1-13-9-4-2-3-5-10(9)14-7-8(12)6-11/h2-5,8,11-12H,6-7H2,1H3 checkY

Guaifenesin, sold under the brand name Mucinex among others,[2] is a medication used to try to help cough out phlegm from the airways.[1] It is unclear if it decreases coughing.[1] Use is not recommended in children less than 6 years old.[5] It is often used in combination with other medications.[1] It is taken by mouth.[1]

Side effects may include dizziness, sleepiness, skin rash, and nausea.[2] While it has not been properly studied in pregnancy, it appears to be safe.[6] It is believed to work by making airway secretions more liquid.[1]

Guaifenesin has been used medically since at least 1933.[7] It is available as a generic medication and over the counter.[1][6] In the United States the wholesale cost is less than US$0.10 per dose.[8] In 2017, it was the 234th most commonly prescribed medication in the United States, with more than two million prescriptions.[9][10]

Medical use

Guaifenesin is used to try to help with coughing up thick mucus and is sometimes combined with dextromethorphan, an antitussive (cough suppressant).[11] It is also combined with ephedrine to produce tablets for symptomatic relief of asthma.


The defined daily dose is 900 mg by mouth or by injection.[3]

Side effects

Side-effects of guaifenesin include nausea, vomiting, formation of kidney stones,[12] diarrhea, and constipation.[13] Nausea and vomiting can be reduced by taking guaifenesin with meals.[2] The risk of forming kidney stones during prolonged use can be reduced by maintaining good hydration and increasing the pH of urine. Rarely, severe allergic reactions may occur, including a rash or swelling of the lips or gums, which may require urgent medical assistance. Mild dry mouth or chapped lips may also occur when taking this medication. Drinking a glass of water is recommended with each dose of guaifenesin.[14]


Effects of guaifenesin on mucus in chronic (or acute) hypersecretory respiratory conditions[15]

Mechanism of action

Guaifenesin is thought to act as an expectorant by increasing the volume and reducing the viscosity of secretions in the trachea and bronchi. It has been said to aid in the flow of respiratory tract secretions, allowing ciliary movement to carry the loosened secretions upward toward the pharynx.[16] Thus, it may increase the efficiency of the cough reflex and facilitate removal of the secretions.

Guaifenesin has muscle relaxant and anticonvulsant properties and may act as an NMDA receptor antagonist.[17]


Similar medicines derived from the guaiac tree were in use as a generic remedy by American indigenous peoples when explorers reached North America in the 16th century. The Spanish encountered guaiacum wood "when they conquered Santo Domingo; it was soon brought back to Europe, where it acquired an immense reputation in the sixteenth century as a cure for syphilis and certain other diseases..."[18]

The 1955 edition of the Textbook of Pharmacognosy states: "Guaiacum has a local stimulant action which is sometimes useful in sore throat. The resin is used in chronic gout and rheumatism, whilst the wood is an ingredient in the compound concentrated solution of sarsaparilla, which was formerly much used as an alternative in syphilis."[18]

In the US, Guaifenesin was first approved by the Food and Drug Administration (FDA) in 1952. Although previously deemed "Generally Regarded as Safe" in its original approval, the drug received a New Drug Application for the extended-release version, which won approval on July 12, 2002. Because of this, the FDA then issued letters to other manufacturers of timed-release guaifenesin to stop marketing their unapproved versions, leaving Adams Respiratory Therapeutics in control of the market. Adams was subsequently acquired by Reckitt Benckiser, based on the strength of the marketing generated by Adams' Mucinex brand.[19][20]

Society and culture


In the United States the wholesale cost is less than US$0.10 per dose.[8] In 2017, it was the 234th most commonly prescribed medication in the United States, with more than two million prescriptions.[9][10]


Guaifenesin taken by mouth as pills or syrups.[1] It is available under many brand names. Single-ingredient formulations of guaifenesin are available, and it is also included in many other over-the-counter cough and cold remedy combinations (usually in conjunction with dextromethorphan, paracetamol (acetaminophen), ephedrine, pseudoephedrine, or phenylephrine).

Combination guaifenesin and pseudoephedrine is sold under the brand name Mucinex D, in which "D" refers to the presence of pseudoephedrine, a decongestant.[21]

Veterinary use

Guaifenesin's neurological properties first became known in the late 1940s. Guaifenesin is a centrally acting muscle relaxant used routinely in large-animal veterinary surgery. Guaifenesin is used in combination with, for example, ketamine, since guaifenesin does not produce analgesia nor does it produce unconsciousness.[22][23]


The guaifenesin protocol was studied as a method to treat fibromyalgia; a one-year double-blind study found that the treatment performs no better than placebo.[24][25] Guaifenesin is not approved by the FDA for the treatment of fibromyalgia.

Guaifenesin was studied as a method to improve the possibility of conception, by thinning and increasing the stretchability (improved spinnbarkeit) of the cervical mucus, during the few days before ovulation, thus facilitating sperm penetration.[26][27]

See also


  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 "Guaifenesin Monograph for Professionals". American Society of Health-System Pharmacists. Archived from the original on 15 April 2019. Retrieved 25 March 2019.
  2. 2.0 2.1 2.2 2.3 "Guaifenesin". Archived from the original on 2017-12-29. Retrieved 2019-03-25.
  3. 3.0 3.1 "WHOCC - ATC/DDD Index". Archived from the original on 7 August 2020. Retrieved 9 September 2020.
  4. Aluri JB, Stavchansky S (1993). "Determination of guaifenesin in human plasma by liquid chromatography in the presence of pseudoephedrine". J Pharm Biomed Anal. 11 (9): 803–8. doi:10.1016/0731-7085(93)80072-9. PMID 8218524. Archived from the original on 2021-08-28. Retrieved 2022-03-14.
  5. British national formulary : BNF 76 (76 ed.). Pharmaceutical Press. 2018. p. 295. ISBN 9780857113382.
  6. 6.0 6.1 Weiner, Carl P.; Rope, Kate (2013). The Complete Guide to Medications During Pregnancy and Breastfeeding: Everything You Need to Know to Make the Best Choices for You and Your Baby. St. Martin's Press. p. PT282. ISBN 9781250037206.
  7. Riviere, Jim E.; Papich, Mark G. (2013). Veterinary Pharmacology and Therapeutics. John Wiley & Sons. p. 287. ISBN 9781118685907. Archived from the original on 2019-03-27. Retrieved 2019-03-25.
  8. 8.0 8.1 "NADAC as of 2019-02-27". Centers for Medicare and Medicaid Services. Archived from the original on 2019-03-06. Retrieved 3 March 2019.
  9. 9.0 9.1 "The Top 300 of 2020". ClinCalc. Archived from the original on 12 February 2021. Retrieved 11 April 2020.
  10. 10.0 10.1 "Guaifenesin - Drug Usage Statistics". ClinCalc. Archived from the original on 8 July 2020. Retrieved 11 April 2020.
  11. "Guaifenesin DM". Archived from the original on 2013-10-15.
  12. Bennett S, Hoffman N, Monga M (December 2004). "Ephedrine- and guaifenesin-induced nephrolithiasis". J Altern Complement Med. 10 (6): 967–9. doi:10.1089/acm.2004.10.967. PMID 15673990.
  13. Guaifenesin Side Effects[unreliable source?] Archived 2018-09-03 at the Wayback Machine
  14. Guaifenesin Archived 2016-07-05 at the Wayback Machine
  15. Albrecht, Helmut H.; Dicpinigaitis, Peter V.; Guenin, Eric P. (11 December 2017). "Role of guaifenesin in the management of chronic bronchitis and upper respiratory tract infections". Multidisciplinary Respiratory Medicine. 12: 31. doi:10.1186/s40248-017-0113-4. ISSN 1828-695X.
  16. Gutierrez, K. (2007). Pharmacotherapeutics: Clinical Reasoning in Primary Care. W.B. Saunders Co.
  17. Keshavarz M, Showraki A, Emamghoreishi M (2013). "Anticonvulsant Effect of Guaifenesin against Pentylenetetrazol-Induced Seizure in Mice". Iran J Med Sci. 38 (2): 116–21. PMC 3700057. PMID 23825891.
  18. 18.0 18.1 Wallis, Thomas E. (1955). Textbook of Pharmacognosy.
  19. "Announcements RB Press release - 10/12/2007". Archived from the original on 15 July 2011. Retrieved 16 November 2010.
  20. Goldstein, Jacob (25 May 2007). "FDA Bumps Phlegm-Fighters From Market". The Wall Street Journal. Archived from the original on 27 June 2016. Retrieved 16 November 2010.
  21. "Mucinex D Website". Reckitt Benckiser. Archived from the original on 3 August 2017. Retrieved 3 August 2017.
  22. Tranquilli, W. J., Thurmon, J. C., and Grimm, K. A. 2007. Lumb and Jones’ Veterinary Anesthesia and Analgesia. Blackwell Publishing. Chapter: Centrally Acting Muscle Relaxants.
  23. Valverde A (Apr 2013). "Balanced anesthesia and constant-rate infusions in horses". Vet Clin North Am Equine Pract. 29 (1): 89–122. doi:10.1016/j.cveq.2012.11.004.
  24. "Consumer Alert — Guaifenesin for Fibromyalgia". Archived from the original on 2011-10-23. Retrieved 2012-01-04.
  25. Bennett RM, De Garmo P, Clark SR (1996). "A Randomized, Prospective, 12 Month Study To Compare The Efficacy Of Guaifenesin Versus Placebo In The Management Of Fibromyalgia" (reprint). Arthritis and Rheumatism. 39 (Supplement9): S212. doi:10.1002/art.1780391402. Archived from the original on 2014-02-09. Retrieved 2011-11-25.
  26. Weschler, Toni (2002). Taking Charge of Your Fertility (Revised ed.). New York: HarperCollins. p. 52. ISBN 0-06-093764-5.
  27. Check JH, Adelson HG, Wu CH (May 1982). "Improvement of cervical factor with guaifenesin". Fertility and Sterility. 37 (5): 707–708. doi:10.1016/s0015-0282(16)46287-4.

External links

External sites: