Over-the-counter medication · Expectorant
guaifenesin
Also sold as Mucinex. This medicine helps with coughs caused by minor throat and lung irritation.
Data updated 2026-05-15
- 29,404
- FDA reportsModerately reported
- 1
- Recall record
What the data shows
guaifenesin (Mucinex) is an over-the-counter Expectorant, reported at a middle-of-the-pack volume (29,404 FDA reports).
Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.
guaifenesin (Mucinex) is an over-the-counter Expectorant. This medicine helps with coughs caused by minor throat and lung irritation.
Guaifenesin (Mucinex) is a medicine that helps to loosen mucus in your lungs. It makes it easier to cough up.
Verify with FDA → · CMS NADAC pricing →
Drug Pricing (NADAC)
Generic Price
$0.01/unit
Generic Available
Yes (17 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
This medicine helps with coughs caused by minor throat and lung irritation.
Common side effects
Nausea, Vomiting, Headache
Key warnings
Do not give to children under 4 years of age.
The sections below are summarized in plain English from guaifenesin's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
How It Works
Guaifenesin is an expectorant. It works by thinning the mucus in your airways. This makes the mucus easier to cough up and clear from your lungs.
How to Take It
Take this medicine every 4 hours as needed. Do not take more than 6 doses in 24 hours. Shake the bottle well before each use. Use the provided dosing cup to measure the correct amount.
This is a plain-language summary of guaifenesin's FDA labeling, not individualized dosing advice. Ask a pharmacist or prescriber before changing how you take this medication.
Pregnancy & Breastfeeding
Talk to your doctor before taking this medicine if you are pregnant or breastfeeding. It is important to weigh the potential benefits against any risks to your baby.
This is a plain-language summary of guaifenesin's FDA labeling, not individualized advice. Ask a pharmacist or prescriber about pregnancy or breastfeeding on this medication.
Missed Dose
If you miss a dose, take it as soon as you remember. Do not take more than 6 doses in 24 hours.
This is a plain-language summary of guaifenesin's FDA labeling, not individualized advice. Ask a pharmacist or prescriber what to do about your specific missed dose.
Storage
Store at room temperature, away from heat and moisture.
Side Effects (from patient reports)
Based on 29,404 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for guaifenesin, by number of reports
- Difficulty breathing
Difficulty breathing
2,178 reports
- Tiredness
Tiredness
1,782 reports
- Feeling sick to your stomach
Feeling sick to your stomach
1,742 reports
- Loose stool
Loose stool
1,645 reports
- Lung infection
Lung infection
1,641 reports
- Cough
Cough
1,557 reports
- Headache
Headache
1,506 reports
- Feeling lightheaded
Feeling lightheaded
1,404 reports
- Pain
Pain
1,251 reports
- Throwing up
Throwing up
945 reports
What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.
Reports over time
Adverse-event reports filed for guaifenesin each year to the FDA Adverse Event Reporting System (FAERS).
Year-to-year volume tracks usage, prescribing, and scrutiny, not a change in per-patient risk. Source: FDA FAERS.
Where guaifenesin sits
guaifenesin has more FDA adverse-event reports than 63% of the drugs FAERS tracks. A high position reflects how widely a drug is used and watched, not how dangerous it is.
Percentile across all drugs PlainMeds tracks by FAERS report volume. The dot is guaifenesin; the line is the median (50th percentile).
FDA Adverse Event Report Analysis
Detailed analysis of 29,404 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 1998–2025.
Total Reports
29,404
Reports Mentioning Death
2,163
7.4% of reports — not proof of cause
Hospitalization Reports
7,581
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 2 | DYSPNOEA | 2,178 |
| 3 | FATIGUE | 1,782 |
| 4 | NAUSEA | 1,743 |
| 5 | DIARRHOEA | 1,645 |
| 6 | PNEUMONIA | 1,641 |
| 7 | COUGH | 1,557 |
| 8 | HEADACHE | 1,506 |
| 9 | DIZZINESS | 1,400 |
| 10 | PAIN | 1,251 |
| 12 | VOMITING | 945 |
| 13 | ASTHENIA | 928 |
| 14 | DEATH | 917 |
| 15 | FALL | 887 |
| 16 | SINUSITIS | 844 |
| 17 | MALAISE | 840 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
Do not give to children under 4 years of age.
Common Questions
What is guaifenesin used for?
How often can I take this medicine?
Can I give this to my child?
What should I do if I miss a dose?
Are there any side effects?
Can I take this while pregnant?
How should I store this medicine?
Can I take this with other medicines?
What if it doesn't seem to be working?
Do I need a prescription for this medicine?
What are the common side effects of guaifenesin?
What drug class is guaifenesin?
Is guaifenesin safe during pregnancy?
Has guaifenesin been recalled?
Active Recalls
CGMP Deviations: Firm went out of business and could no longer continue stability studies.
Akorn, Inc.
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What the FDA Data Shows for guaifenesin
The FDA label for guaifenesin (sold under brand names such as Mucinex) classifies it as an over-the-counter product in the Expectorant class. This medicine helps with coughs caused by minor throat and lung irritation. Official labeling lists 4 commonly reported side effects, including Nausea, Vomiting, Headache.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 29,404 voluntary reports. Interaction data is drawn directly from FDA-approved prescribing information. NADAC pricing from CMS shows a generic unit cost of $0.01.
Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history (currently 1 recall record on file), and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice, always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: October 14, 2025
Read our methodology - how this data is sourced, computed, and verified.
Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled and last refreshed May 2026. See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a correction.
All federal data sources used on this page
- FDA Orange Book - approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed - NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) - post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm - standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files - federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database - current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages