Guaifenesin is an active ingredient used in various over-the-counter and prescription medications. It is effective in loosening phlegm and thinning mucus that is experienced with a cold or other similar respiratory illnesses, notes eMedTV. It is usually described as an expectorant. As with any medication, guaifenesin has the risk of side effects. The drug should only be used as directed.
Headache
A headache is a common side effect of guaifenesin, states MedlinePlus. If this side effect lasts for a long period of time or is severe, the user should seek medical treatment.
Nausea
Some users may experience mild stomach upset, such as nausea. This can be reduced by ensuring the medication is not taken on an empty stomach. Some individuals with moderate mucus drainage may notice more nausea from the mucus entering the stomach, as the mucus is thinned from taking guaifenesin. If vomiting occurs, contact a doctor to discuss whether the drug should be continued. According to eMedTV, some stomach pain can occur with the use of guaifenesin.
Other Symptoms
Using guaifenesin can cause mild to moderate dizziness in some individuals. Drowsiness or trouble sleeping can also occur depending on the individual. Drugs.com points out that guaifenesin is often used in combination with various other drugs that have more significant side effects. Most often, the discomfort the user experiences is due to the other drugs included in the medicine, such as pseudoephedrine, than from the guaifenesin.
