Cough medicine as a muscle relaxant?

Anybody who exercises on a regular basis will be familiar with the feeling of tight, stiff muscles. After a long, hard training session, and even venturing into the following day or two, sore muscles come with the territory….and if you’re anything like me, muscle soreness is pretty much a never ending experience.

Stretching, massage, hot and cold therapies, anti-inflammatories and simple rest can help to relieve aching muscles. But for those with ongoing muscle soreness, is there anything else that may help? Well, maybe…..


Guaifenesin is an expectorant, which has been traditionally used in cough medicines in order to help loosen up phlegm on the lungs, so it can be coughed up more easily. Essentially, guaifenesin breaks down thick mucus secretions in the lungs, so they are less viscous, which allows the body to expel them more efficiently when coughing.

However, guaifenesin is used as a muscle relaxant in horses. As such, it is used as a part of many anaesthetic procedures, and is actually a prohibited drug during competition for race horses!

So what about in humans? In 2017, a study was published on the muscle relaxant effects guaifenesin may provide for upper back, neck and shoulder pain. Although the study numbers were quite small, the results did show that at doses of 1200 mg, taken twice a day, guaifenesin may potentially provide symptom relief from upper back, neck, and shoulder musculoskeletal pain and discomfort.

Guaifenesin is also used by some people as a treatment for pain associated with fibromyalgia. But a small study did suggest that guaifenesin showed no real benefit compared to placebo over the course of a year for fibromyalgia pain.


Anecdotally, some individuals have found benefit from the use of guaifenesin. Of course, anecdotal evidence does not mean the drug actually works for sore muscles!

The small studies which have been produced provide some evidence that guaiphenesin may actually give some relief from muscle pain. But further research, on a much larger scale, is definitely needed to determine if guaifenesin can be used as a muscle relaxant.

For now? Experimenting with unproven drug treatments isn’t the best of ideas. Guaifenesin is a comparatively safe drug; but maybe just stick to the traditional treatments for muscle aches and pains until the research comes back with some more concrete evidence!

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