An over the counter drug which is commonly used to thin mucus to aid in draining of the sinuses for chronic or acute sinusitis, and to loosen mucus to relieve a cough. It has been available for over 70 years and has very few side effects. In rare cases the patient may experience nausea, headache, and fatigue. It is one of the active ingredients in Robitussin® DM.
In addition, guaifenesin has been found to be effective in treatment of fibromyalgia, although it is unknown why. It has been found that after taking guaifenesin, phosphate, calcium, and oxalate levels in the patient's urine were significantly higher, and perhaps the flushing of these from the body helps to lessen the symptoms of fibromyalgia, although since the cause for fibromyalgia is not know, the reason for the effectiveness of guaifenesin is also a mystery. Aspirin and aloe should be avoided with this treatment as it blocks the effect of guaifenesin. Patients will initially begin to feel significantly worse, and this is the best sign that a proper dosage has been given and that it is working. After a short amount of time, the symptoms will lessen and occur less frequently.