Drug · FAERS side-effect profile with label screen
Guaifenesin side effects: what 30,302 FDA adverse event reports show
Drug class
Expectorant
FDA label (Established Pharmacologic Class)
Brand names
Mucus Relief
openFDA label
Who reports
30,302 reports · 50% serious · 2,205 with death outcome · 63% female
openFDA FAERS counts, all years, deduplication not applied
Used for
(S) helps loosen phlegm (mucus) and thin bronchial secretions to rid the bronchial passageways of bothersome mucus and make coughs more productive
FDA label, Indications and Usage
Boxed warning
None in the current label
How to read this page. FAERS is a spontaneous-reporting system: counts are not incidence rates and a signal is not proof of causation.
Each reaction below is run through an automated screen — is the term in the FDA label (known), in the indications (the disease being treated), an administrative/coding term, or none of these (unlabeled)?
That screen is mechanical text matching, not a causality assessment. The 30 hand-written Bradford Hill assessments are on the causality assessment page. Not medical advice.
Causality screen of the 40 strongest signals
Reporting / coding artifact 3Lab value / disease marker 1No label text to screen 36
What the badges mean
- Reporting / coding artifact An administrative, monitoring or exposure term (product issue, off-label use, 'test normal', overdose...). Not a biological reaction; a high PRR here reflects how reports are coded.
- Lab value / disease marker A laboratory result, investigation or disease-activity marker (antibody positive, CRP abnormal, swollen joint count) not described in the label. These usually mirror the monitored disease or testing protocol rather than a drug effect; not screened further.
- Not in label — unassessed Not found in the label text, not an artifact pattern. This is a genuine candidate for a formal causality assessment (Bradford Hill / WHO-UMC); it has NOT had one here.
- No label text to screen No validated FDA label was retrievable for this product, so the screen could not run. Disproportionality only.
Strongest disproportionality signals
Flagged terms (PRR ≥ 2, χ² ≥ 4, n ≥ 10), ranked by PRR; infinite PRRs (no comparator reports) excluded. The EBGM column is a second, shrinkage-based estimate (MGPS) with its 5th percentile EB05 and the BCPNN IC025; a pair flagged by PRR alone is marked PRR-only and should be read as fragile. The strata column recomputes the PRR on serious reports only (and, for the 300 most-reported drugs, adjusted for age band), and flags pairs whose reports are unusually skewed by sex or come mostly from consumers. Each row also shows the PRR against the other drugs of the same FDA class, which removes most confounding by the condition being treated, and a calibrated p-value: on validation, known non-causes average an ROR of about 2, so significance is judged against that empirical null (✓ = p < 0.05 after calibration). 1,132 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.
Show:
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Vaginal flatulence | 35 | 89.3 62.8–127.0ROR 89.4 · calibrated p 6e-7 ✓ | 75.9 EB05 57.1 · IC025 +4.7 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=35 · ♀ 100% (drug 63%) · 100% clinician | not reported in cached trials |
| Chronic kidney disease-mineral and bone disorder | 35 | 23.2 16.6–32.5ROR 23.2 · calibrated p 0.001 ✓ | 22.2 EB05 16.7 · IC025 +3.5 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=35 | not reported in cached trials |
| Increased viscosity of upper respiratory secretion | 21 | 19.8 12.8–30.5ROR 19.8 · calibrated p 0.003 ✓ | 18.9 EB05 12.9 · IC025 +3.0 3/3 methods agree | No label text to screen label has no adverse-reaction text | – | not reported in cached trials |
| Hyperparathyroidism secondary | 63 | 17.6 13.7–22.6ROR 17.7 · calibrated p 0.004 ✓ | 17.1 EB05 13.8 · IC025 +3.5 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=63 | not reported in cached trials |
| Rhonchi | 33 | 16.8 11.9–23.8ROR 16.9 · calibrated p 0.005 ✓ | 16.2 EB05 12.0 · IC025 +3.2 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=32 | not reported in cached trials |
| Nephrogenic anaemia | 110 | 16.6 13.8–20.1ROR 16.7 · calibrated p 0.005 ✓ | 16.2 EB05 13.8 · IC025 +3.6 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=109 | not reported in cached trials |
| Infusion site discharge | 38 | 15.7 11.4–21.6ROR 15.7 · calibrated p 0.007 ✓ | 15.2 EB05 11.4 · IC025 +3.2 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=28 · ♀ 100% (drug 63%) · 79% consumer | not reported in cached trials |
| Product size issue | 117 | 15.5 12.9–18.7ROR 15.6 · calibrated p 0.006 ✓ | 15.2 EB05 13.0 · IC025 +3.5 3/3 methods agree | Reporting / coding artifact | serious n=20 · 100% consumer | not reported in cached trials |
| Female genital tract fistula | 36 | 14.8 10.6–20.5ROR 14.8 · calibrated p 0.009 ✓ | 14.2 EB05 10.5 · IC025 +3.1 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=36 · ♀ 100% (drug 63%) · 100% clinician | not reported in cached trials |
| Bronchitis chronic | 50 | 14.3 10.8–19.0ROR 14.4 · calibrated p 0.010 ✓ | 13.9 EB05 10.8 · IC025 +3.2 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=47 | not reported in cached trials |
| Chronic respiratory failure | 24 | 14.2 9.5–21.3ROR 14.2 · calibrated p 0.012 ✓ | 13.4 EB05 9.1 · IC025 +2.8 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=24 | not reported in cached trials |
| Reduced facial expression | 20 | 14.1 9.0–21.9ROR 14.1 · calibrated p 0.013 ✓ | 13.1 EB05 8.5 · IC025 +2.6 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=20 · 100% clinician | not reported in cached trials |
| Pneumonia pseudomonal | 30 | 13.9 9.7–20.0ROR 13.9 · calibrated p 0.012 ✓ | 13.3 EB05 9.5 · IC025 +2.9 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=30 | not reported in cached trials |
| Infusion site mass | 21 | 13.9 9.0–21.3ROR 13.9 · calibrated p 0.013 ✓ | 13.0 EB05 8.5 · IC025 +2.7 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=14 | not reported in cached trials |
| Foreign body in respiratory tract | 26 | 13.8 9.4–20.4ROR 13.8 · calibrated p 0.012 ✓ | 13.1 EB05 9.1 · IC025 +2.8 3/3 methods agree | No label text to screen label has no adverse-reaction text | 100% consumer | not reported in cached trials |
| Incorrect drug administration duration | 553 | 13.7 12.6–14.8ROR 13.9 · calibrated p 0.010 ✓ | 13.4 EB05 12.5 · IC025 +3.6 3/3 methods agree | Reporting / coding artifact | serious PRR 7.1 · 95% consumer | not reported in cached trials |
| Radiculopathy | 47 | 12.5 9.4–16.7ROR 12.5 · calibrated p 0.016 ✓ | 12.0 EB05 9.3 · IC025 +3.0 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=47 · 100% clinician | not reported in cached trials |
| Chronic sinusitis | 65 | 12.2 9.5–15.6ROR 12.2 · calibrated p 0.017 ✓ | 11.8 EB05 9.5 · IC025 +3.1 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=59 · ♀ 85% (drug 63%) | not reported in cached trials |
| Sputum increased | 36 | 12.0 8.6–16.6ROR 12.0 · calibrated p 0.020 ✓ | 11.3 EB05 8.3 · IC025 +2.8 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=19 | not reported in cached trials |
| Rebound acid hypersecretion | 52 | 11.9 9.1–15.7ROR 11.9 · calibrated p 0.019 ✓ | 11.4 EB05 8.9 · IC025 +3.0 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=52 | not reported in cached trials |
| Acute sinusitis | 29 | 11.8 8.2–17.1ROR 11.8 · calibrated p 0.021 ✓ | 11.1 EB05 7.8 · IC025 +2.7 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=27 | not reported in cached trials |
| Infusion site pruritus | 51 | 11.5 8.7–15.1ROR 11.5 · calibrated p 0.022 ✓ | 11.0 EB05 8.6 · IC025 +2.9 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=33 | not reported in cached trials |
| Seasonal allergy | 229 | 11.4 10.0–13.0ROR 11.5 · calibrated p 0.020 ✓ | 11.2 EB05 10.0 · IC025 +3.2 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=123 · 75% consumer | not reported in cached trials |
| Obliterative bronchiolitis | 21 | 11.1 7.2–17.1ROR 11.1 · calibrated p 0.029 ✓ | 10.0 EB05 6.6 · IC025 +2.4 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=21 | not reported in cached trials |
| Incorrect product administration duration | 315 | 10.9 9.7–12.2ROR 11.0 · calibrated p 0.023 ✓ | 10.7 EB05 9.7 · IC025 +3.2 3/3 methods agree | Reporting / coding artifact | serious n=32 · 96% consumer | not reported in cached trials |
| Multiple allergies | 117 | 10.5 8.7–12.5ROR 10.5 · calibrated p 0.029 ✓ | 10.2 EB05 8.7 · IC025 +3.0 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=95 | not reported in cached trials |
| Infusion site rash | 20 | 10.3 6.6–16.0ROR 10.3 · calibrated p 0.037 ✓ | 9.1 EB05 5.9 · IC025 +2.3 3/3 methods agree | No label text to screen label has no adverse-reaction text | – | not reported in cached trials |
| Proctitis | 38 | 9.5 6.9–13.1ROR 9.5 · calibrated p 0.043 ✓ | 8.8 EB05 6.6 · IC025 +2.5 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=38 · ♀ 100% (drug 63%) · 100% clinician | not reported in cached trials |
| Lower respiratory tract congestion | 23 | 9.5 6.3–14.3ROR 9.5 · calibrated p 0.047 ✓ | 8.4 EB05 5.7 · IC025 +2.3 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=16 · 100% consumer | not reported in cached trials |
| Upper-airway cough syndrome | 110 | 9.4 7.8–11.3ROR 9.4 · calibrated p 0.041 ✓ | 9.1 EB05 7.7 · IC025 +2.8 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=64 | not reported in cached trials |
| Breath sounds abnormal | 66 | 9.4 7.3–11.9ROR 9.4 · calibrated p 0.043 ✓ | 8.9 EB05 7.2 · IC025 +2.7 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=57 | not reported in cached trials |
| Infusion site haemorrhage | 43 | 9.3 6.9–12.5ROR 9.3 · calibrated p 0.046 ✓ | 8.7 EB05 6.6 · IC025 +2.6 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=23 · 74% consumer | not reported in cached trials |
| Infusion site bruising | 28 | 9.2 6.3–13.4ROR 9.2 · calibrated p 0.049 ✓ | 8.4 EB05 5.9 · IC025 +2.4 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=19 · ♀ 100% (drug 63%) | not reported in cached trials |
| Echocardiogram abnormal | 18 | 9.0 5.7–14.4ROR 9.0 · calibrated p 0.057 | 7.8 EB05 5.0 · IC025 +2.1 3/3 methods agree | Lab value / disease marker | serious n=18 | not reported in cached trials |
| Contrast media allergy | 23 | 9.0 5.9–13.5ROR 9.0 · calibrated p 0.055 | 8.0 EB05 5.4 · IC025 +2.2 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=23 · ♀ 100% (drug 63%) | not reported in cached trials |
| Paranasal sinus discomfort | 47 | 8.7 6.5–11.6ROR 8.7 · calibrated p 0.055 | 8.2 EB05 6.3 · IC025 +2.5 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=20 | not reported in cached trials |
| Conduction disorder | 22 | 8.4 5.5–12.8ROR 8.4 · calibrated p 0.068 | 7.4 EB05 5.0 · IC025 +2.1 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=22 | not reported in cached trials |
| Chronic obstructive pulmonary disease | 626 | 8.4 7.8–9.1ROR 8.5 · calibrated p 0.054 | 8.3 EB05 7.7 · IC025 +2.9 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious PRR 10.2 | not reported in cached trials |
| Respiratory tract congestion | 190 | 8.3 7.2–9.6ROR 8.4 · calibrated p 0.058 | 8.1 EB05 7.2 · IC025 +2.8 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious PRR 12.0 · 76% consumer | not reported in cached trials |
| Foreign body in throat | 36 | 8.3 6.0–11.5ROR 8.3 · calibrated p 0.066 | 7.6 EB05 5.7 · IC025 +2.3 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious n=14 · 100% consumer | not reported in cached trials |
Trial evidence (ClinicalTrials.gov)
✓ Trial adverse-event data found on ClinicalTrials.gov
Largest completed trials with posted results that list Guaifenesin as a study intervention. The right-hand column of the signal table shows whether each FAERS term was also recorded in these trials, with a real denominator (0 of 40 signal terms matched).
- NCT01537081 — Safety and Efficacy of Mucinex and IR Guaifenesin the Treatment of Symptoms of Acute Upper Respiratory Tract I (N=2810, PHASE2, PHASE3; 8 AE terms posted; arms: Mucinex 2400 mg/Day; Immediate-release Guaifenesin 800 mg/Day; Placebo)
- NCT01202279 — Safety and Efficacy Study of Guaifenesin and Pseudoephedrine for Symptomatic Therapy to Treat Acute RTI (N=1179, PHASE4; 4 AE terms posted; arms: Mucinex D; Placebo)
Caveats: trial populations, doses and follow-up differ from the reporting population; AE terms are sponsor-coded and matched here by wording; absence from a trial list means the term was not reported above the sponsor's frequency threshold, not that it cannot occur.
Most frequently reported reactions
By raw co-report count, regardless of disproportionality. Common terms here are often the illness itself or generic outcomes.
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Drug ineffective (drug did not work) | 2,522 | 1.3 1.3–1.4ROR 1.4 · calibrated p 0.545 | 1.3 EB05 1.3 · IC025 +0.3 | Reporting / coding artifact | serious PRR 0.9 · 83% consumer | not reported in cached trials |
| Dyspnoea (shortness of breath) | 2,264 | 2.8 2.7–2.9ROR 2.9 · calibrated p 0.653 | 2.8 EB05 2.7 · IC025 +1.4 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious PRR 3.1 | not reported in cached trials |
| Fatigue (tiredness) | 1,855 | 1.7 1.6–1.7ROR 1.7 · calibrated p 0.766 | 1.7 EB05 1.6 · IC025 +0.6 | No label text to screen label has no adverse-reaction text | serious PRR 2.2 | not reported in cached trials |
| Nausea | 1,822 | 1.6 1.5–1.7ROR 1.6 · calibrated p 0.730 | 1.6 EB05 1.5 · IC025 +0.6 | No label text to screen label has no adverse-reaction text | serious PRR 2.1 | NCT01537081: 19/1,122 (1.7%) on Guaifenesin; 6/561 (1.1%) control |
| Diarrhoea (diarrhea) | 1,720 | 1.9 1.8–1.9ROR 1.9 · calibrated p 0.890 | 1.8 EB05 1.8 · IC025 +0.8 | No label text to screen label has no adverse-reaction text | serious PRR 1.9 | NCT01537081: 17/1,122 (1.5%) on Guaifenesin; 9/561 (1.6%) control |
| Pneumonia (lung infection) | 1,708 | 3.7 3.5–3.8ROR 3.8 · calibrated p 0.411 | 3.7 EB05 3.5 · IC025 +1.8 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious PRR 4.3 | NCT01537081: 1/561 (0.2%) control (serious AE) |
| Cough | 1,649 | 4.1 3.9–4.3ROR 4.3 · calibrated p 0.331 | 4.1 EB05 3.9 · IC025 +1.9 3/3 methods agree | No label text to screen label has no adverse-reaction text | serious PRR 4.6 | not reported in cached trials |
| Headache | 1,586 | 1.8 1.7–1.8ROR 1.8 · calibrated p 0.827 | 1.8 EB05 1.7 · IC025 +0.7 | No label text to screen label has no adverse-reaction text | serious PRR 2.1 | NCT01537081: 27/1,122 (2.4%) on Guaifenesin; 11/561 (2.0%) control |
| Dizziness | 1,449 | 2.0 1.9–2.1ROR 2.1 · calibrated p 0.980 | 2.0 EB05 1.9 · IC025 +0.9 | No label text to screen label has no adverse-reaction text | serious PRR 2.1 · 73% consumer | NCT01537081: 8/1,122 (0.7%) on Guaifenesin; 3/561 (0.5%) control |
| Pain | 1,293 | 1.5 1.4–1.5ROR 1.5 · calibrated p 0.625 | 1.5 EB05 1.4 · IC025 +0.4 | No label text to screen label has no adverse-reaction text | serious PRR 2.0 | not reported in cached trials |
| Off label use (used outside approved label) | 1,016 | 0.8 0.8–0.9ROR 0.8 · calibrated p 0.186 | 0.8 EB05 0.8 · IC025 -0.4 PRR-only: not supported by EBGM or IC | Reporting / coding artifact | serious PRR 0.9 | not reported in cached trials |
| Vomiting | 979 | 1.4 1.4–1.5ROR 1.5 · calibrated p 0.615 | 1.4 EB05 1.4 · IC025 +0.4 | No label text to screen label has no adverse-reaction text | serious PRR 1.7 | NCT01537081: 3/1,122 (0.3%) on Guaifenesin; 4/561 (0.7%) control |
| Asthenia (weakness) | 952 | 1.8 1.6–1.9ROR 1.8 · calibrated p 0.816 | 1.8 EB05 1.7 · IC025 +0.7 | No label text to screen label has no adverse-reaction text | serious PRR 2.2 | not reported in cached trials |
| Death | 948 | 0.8 0.7–0.8ROR 0.8 · calibrated p 0.158 | 0.8 EB05 0.7 · IC025 -0.5 PRR-only: not supported by EBGM or IC | Outcome field, not a reaction | serious PRR 0.9 | not reported in cached trials |
| Fall | 924 | 1.9 1.8–2.1ROR 2.0 · calibrated p 0.918 | 1.9 EB05 1.8 · IC025 +0.8 | No label text to screen label has no adverse-reaction text | serious PRR 2.3 | not reported in cached trials |
Unlabeled candidate signals
Every screened signal with n ≥ 20 was either labeled, an indication term, or an artifact pattern — no unlabeled candidate stood out in the top signals.
Want to assess one of these properly? The runbook describes the Bradford Hill / trial-evidence workflow used on the assessment page, and handoff_top1000_signals.csv lists the strongest unassessed pairs across all drugs.
Common questions
What are the most reported side effects of Guaifenesin?
In FDA FAERS, the most frequently co-reported reaction terms for Guaifenesin are dyspnoea, fatigue, nausea, diarrhoea, pneumonia, cough. These are report counts, not rates: FAERS has no denominator, reporting is voluntary and uneven, and a term can be reported because of the illness being treated rather than the drug.
Does Guaifenesin have an FDA boxed warning?
No. The FDA label retrieved for Guaifenesin has no boxed warning; see the label's Warnings and Precautions for the recognised risks.
Do FAERS signals prove that Guaifenesin causes these side effects?
No. A disproportionality signal (PRR, ROR) means a reaction is reported more often with this drug than with others in the database. That can reflect a real effect, but also the disease being treated, stimulated reporting after news or litigation, co-medications, or how reports are coded. Causality needs temporality, dose-response, biological plausibility, consistency across data sources and, ideally, trial or cohort evidence. This page screens each term against the FDA label and ClinicalTrials.gov results; it does not establish causation.
Sources & methods
- FDA label via openFDA (set ID c648e711-e944-4574-83b3-ccce8732384e, effective 20250602; matched on
openfda.generic_name.exact:"GUAIFENESIN" AND openfda.product_type:"HUMAN PRESCRIPTION DRUG") - Bayesian shrinkage measures computed offline over all 1,317,300 cached pairs: BCPNN information component (IC, with Norén closed-form IC025) and MGPS empirical-Bayes geometric mean (EBGM, EB05) with a two-component gamma prior fitted by maximum marginal likelihood (α₁=0.57, β₁=0.02, α₂=1.42, β₂=0.70, w=0.17); unstratified
- FAERS pair statistics from the OpenPV build of 2026-09-14 (openFDA
count=aggregation, fieldpatient.drug.openfda.generic_name.exact, 1,172 reaction terms, min 3 co-reports); PRR/ROR with 95% CI, chi-square with Yates correction - Serious-only and stratified counts (serious:1, patient.patientsex, primarysource.qualification) from openFDA count queries; serious-only PRR uses the drug serious report total and the term global serious total (N_serious=11,882,979); strata shown only when n ≥ 20
- Seriousness and sex counts from openFDA
count=serious,patient.patientsex,seriousnessdeath - ClinicalTrials.gov API v2 (query
GUAIFENESIN, results-bearing studies sorted by enrollment)
Page generated 2026-10-14. Label and PubChem text are retrieved automatically and may lag the current label; always check the current prescribing information. OpenPV is a beta research tool of the Open Source Medicine Foundation.