Conclusion: The results of this review have to be interpreted with caution because the number of studies in each category of cough preparations was small. Availability, dosing and duration of use of over-the-counter cough medicines vary significantly in different countries. Many studies were poorly reported making assessment of risk of bias difficult and studies were also very different from each other, making evaluation of overall efficacy difficult. There is no good evidence for or against the effectiveness of OTC medicines in acute cough. This should be taken into account when considering prescribing a
PubMed 25420096 ↗Guaifenesin
The short answer. There isn't much data on Guaifenesin yet — 11 mentions, 5 with a clear outcome — so treat these numbers as anecdotal. It is well studied — 6 meta-analyses on PubMed. The most common complaint is kidney stones.
From 11 mentions in total — the rest didn't say how it went and aren't counted.
What Guaifenesin does, according to users
Of the people who reported each effect, the share who said it got better.
What the research says
Systematic reviews and meta-analyses from PubMed, with their published conclusions.
3+ meta-analyses or systematic reviews and 10+ randomized controlled trials in humans. The grade measures how much human research exists — read the conclusions below for what it found.
Conclusion: Ephedrine and guaifenesin have been shown to cause nephrolithiasis in cases of abuse when taken individually or in combination. It is important for the clinician to be aware of the potential for these compounds to cause nephrolithiasis.
PubMed 15673990 ↗Conclusion: There is no good evidence for or against the effectiveness of OTC medicines in acute cough. The results of this review have to be interpreted with caution due to differences in study characteristics and quality. Studies often showed conflicting results with uncertainty regarding clinical relevance. Higher quality evidence is needed to determine the effectiveness of self care treatments for acute cough.
PubMed 22895922 ↗Conclusion: There is no good evidence for or against the effectiveness of OTC medicines in acute cough. The results of this review have to be interpreted with caution due differences in study characteristics and quality. Studies often showed conflicting results with uncertainty regarding clinical relevance. Higher quality evidence is needed to determine the effectiveness of self-care treatments for acute cough.
PubMed 18253996 ↗Dosage people report
Reported side effects
How often each side effect came up across all reports.
What users say
First-hand experiences, quoted verbatim. We show one positive and one negative where both exist.
“Some people say taking too much guaifenesen can cause side effects, but I've never had any negative sides from it.”
“bronkaid contains 400mg of guaifenesin per 25 mg of ephedrine. At my peak i'd like to be taking 75 mg a day of ephedrine thats 1.2g of guaifenesin a day that I really don't need or want.”
“the Guaifenesin is fucking up my throat at something severe, and making my voice sound like an 80-year old chain smoker”
Other options for anxiety
User data from public discussions; research from PubMed. Information only, not medical advice — talk to a doctor before starting, stopping or combining anything. Data updated October 3, 2026. How we rate