What is Guaifenesin Syrup?

Marco Sumayao

Guaifenesin syrup is a liquid medication most often used for the treatment of cough symptoms. The drug is an effective expectorant, allowing patients to dispense phlegm and clear out infected respiratory tracts. Certain formulations of guaifenesin syrup can also contain antitussives, which help loosen phlegm for expectoration. Less common uses for guaifenesin syrup include the treatment of both asthma and gout, maintaining anesthetic treatments in veterinary procedures, and improving the voice quality of singers. Side effects of guaifenesin use include vomiting, nausea, and the development of kidney stones.

Overusing guaifenesin syrup can lead to chapped lips.
Overusing guaifenesin syrup can lead to chapped lips.

Although doctors prescribe guaifenesin syrup to alleviate the symptoms of cough, the medication is not a cure for upper respiratory tract infections. Guaifenesin thins mucus and phlegm lining the body's air passageways; the less viscous mucus is then easier to expel from the system. This provides relief for symptoms such as heavy cough and difficulty breathing. It does not, however, eliminate any of the viral or bacterial causes of cough. Guaifenesin syrup is safe to use in conjunction with many medications that do cure respiratory tract infections, such as erythromycin.

Guaifenesin syrup may be used as an expectorant to help a person cough up phlegm more easily.
Guaifenesin syrup may be used as an expectorant to help a person cough up phlegm more easily.

The remedy is available in forms other than syrups. Patients can purchase guaifenesin granules to dissolve into an orally-taken suspension. Many individuals prefer to take the medication as a pill to avoid unfavorable flavors. Capsules that contain guaifenesin syrup are also available and allow patients to take precise doses of the medication.

Guaifenesin syrup thins mucus.
Guaifenesin syrup thins mucus.

Despite the reported benefits of guaifenesin syrup, experts argue that the medication lacks quantifiable evidence in supporting claims of cough relief. Although using guaifenesin will usually reduce the viscosity of phlegm, there isn't enough empirical data to show that thinner phlegm results in more efficient coughs. In this respect, some doctors advice against the use of guaifenesin, as there is no proven benefit to outweigh its potential side effects.

The side effects of guaifenesin syrup are uncommon and often arise only in cases of overdose. The most common symptom of a guaifenesin overdose is a migraine headache, although the medication can also bring about a general sense of uneasiness. Overconsumption of guaifenesin can lead to signs of dehydration, such as chapped lips and mouth dryness, and kidney failure unless the treatment is supplemented with increased fluid intake. In extremely rare cases, patients might be allergic to guaifenesin, developing rashes and other serious medical issues.

Experts advise that individuals consult their doctors before taking guaifenesin to reduce the risk of harmful side effects. Patients should also report any medications being taken that might develop adverse reactions with guaifenesin. Most doctors advise pregnant women to avoid taking the medication, as it could potentially harm the developing fetus.

Phlegm that is coughed up should be spit out, not swallowed.
Phlegm that is coughed up should be spit out, not swallowed.

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Discussion Comments


@alisha-- I think the slow-release version of guaifenesin cough syrup is much better. It's effective for a longer period of time and since the drug gets released slowly, it's less likely to cause side effects.

Plus, the slow-release comes in tablets, which is great for me because I hate the flavor of the syrup.


@alisha-- I've used guaifenesin syrup before too and I didn't have any bad side effects. It made me cough a little more than usual for the first few hours but that's how expectorants get rid of phlegm.


I used guaifenesin syrup once and I regret it. I was at my sister's house and this is the only cough syrup she had. I couldn't see the doctor until Monday so I thought that this cough syrup would help me get through the weekend.

I used the recommended dose on the bottle and it made me sick. I was very nauseated for hours and ended up vomiting. The worst part is that it really didn't do anything for my cough. I don't know if guaifenesin side effects are so bad for everyone, but this medication doesn't go down well with me.

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