Guaifenesin AC Syrup
WARNING: For all patients taking this drug:This drug has an opioid drug in it. Opioid drugs can put you at risk for drug use disorder. Misuse or abuse of this drug can lead to overdose and death. If you have questions, talk with your doctor.You will be watched closely to make sure you do not misuse this drug or develop drug use disorder.This drug has an opioid drug in it. Severe side effects have happened when opioid drugs were used with benzodiazepines, alcohol, marijuana or other forms of cannabis, or prescription or OTC drugs that may cause drowsiness or slowed actions. This includes slow or troubled breathing and death. Benzodiazepines include drugs like alprazolam, diazepam, and lorazepam. Benzodiazepines may be used to treat many health problems like anxiety, trouble sleeping, or seizures. If you have questions, talk with the doctor.Many drugs interact with this drug and can raise the chance of side effects like deadly breathing problems. Talk with your doctor and pharmacist to make sure it is safe to use this drug with all of your drugs.Do not take with alcohol or products that have alcohol. Unsafe and sometimes deadly effects may happen.Get medical help right away if you feel very sleepy, very dizzy, or if you pass out. Caregivers or others need to get medical help right away if the patient does not respond, does not answer or react like normal, or will not wake up.This drug may cause very bad and sometimes deadly breathing problems. Call your doctor right away if you have slow, shallow, or trouble breathing.Children:This drug is not for use in children younger than 18 years of age. The benefits of taking this drug for a cough due to allergies, a cold, or other infection do not outweigh the risks in children. If your child has been given this drug or if you have any questions, talk with your child's doctor. @ COMMON USES: It is used to thin mucus so it can be taken from the body by coughing.It is used to relieve coughing.
Drug Class
Antitussive, Expectorant
Pharmacologic Class
Opioid Analgesic (antitussive), Guaiacolate derivative (expectorant)
Pregnancy Category
Category C
FDA Approved
Jan 1970
DEA Schedule
Schedule V
Overview
What is this medicine?
This medicine is a combination of two drugs: guaifenesin and codeine. Guaifenesin helps to thin and loosen mucus in your lungs, making it easier to cough up. Codeine is a cough suppressant that works by calming the cough reflex in your brain. It is used to relieve cough and chest congestion caused by colds, flu, or other breathing illnesses.
How to Use This Medicine
Taking Your Medication
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your medication as directed, with or without food. If you experience stomach upset, taking it with food may help. Drink plenty of non-caffeinated fluids, unless your doctor advises you to limit your fluid intake.
To ensure accurate dosing, measure liquid medications carefully using the device provided with the medication. If no device is included, ask your pharmacist for a suitable measuring tool.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, avoiding bathrooms and areas where children or pets can access it. Keep it in a secure, locked location to prevent unauthorized use. Dispose of unused or expired medications properly. Do not flush them down the toilet or pour them down the drain unless instructed to do so by your doctor or pharmacist. If you have questions about disposal, consult your pharmacist, who may be aware of local drug take-back programs.
Missing a Dose
If you take this medication regularly and miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at once or extra doses. If you take this medication as needed, do not exceed the frequency recommended by your doctor.
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your medication as directed, with or without food. If you experience stomach upset, taking it with food may help. Drink plenty of non-caffeinated fluids, unless your doctor advises you to limit your fluid intake.
To ensure accurate dosing, measure liquid medications carefully using the device provided with the medication. If no device is included, ask your pharmacist for a suitable measuring tool.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, avoiding bathrooms and areas where children or pets can access it. Keep it in a secure, locked location to prevent unauthorized use. Dispose of unused or expired medications properly. Do not flush them down the toilet or pour them down the drain unless instructed to do so by your doctor or pharmacist. If you have questions about disposal, consult your pharmacist, who may be aware of local drug take-back programs.
Missing a Dose
If you take this medication regularly and miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at once or extra doses. If you take this medication as needed, do not exceed the frequency recommended by your doctor.
Lifestyle & Tips
- Avoid alcohol while taking this medication, as it can increase drowsiness and risk of serious side effects.
- Do not drive or operate heavy machinery until you know how this medication affects you, as it can cause dizziness and drowsiness.
- Drink plenty of fluids (water) to help loosen mucus and make guaifenesin more effective.
- To prevent constipation, increase fiber in your diet and drink plenty of water. A stool softener or laxative may be needed if constipation becomes severe.
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
10 mL (100 mg guaifenesin / 10 mg codeine) orally every 4-6 hours as needed
Dose Range:
10 - 20 mg
Condition-Specific Dosing:
maximumDailyDose:
60 mL (600 mg guaifenesin / 60 mg codeine) in 24 hours
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Contraindicated in children younger than 12 years of age.
Adolescent:
Contraindicated in adolescents 12 to 18 years of age who have obesity or severe sleep apnea or who have undergone tonsillectomy or adenoidectomy. Use with caution in other adolescents 12-18 years, only if benefits outweigh risks.
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment recommended, monitor for increased sedation.
Moderate:
Reduce dose by 25-50%, monitor closely for increased sedation and respiratory depression.
Severe:
Avoid use or significantly reduce dose (e.g., 50-75% reduction), monitor closely. Codeine metabolites accumulate.
Dialysis:
Avoid use or use with extreme caution and significant dose reduction. Codeine and its active metabolites are dialyzable to some extent, but accumulation can still occur.
Hepatic Impairment:
Mild:
No specific adjustment recommended, monitor for increased sedation.
Moderate:
Reduce dose by 25-50%, monitor closely for increased sedation and respiratory depression.
Severe:
Avoid use or significantly reduce dose (e.g., 50-75% reduction), monitor closely. Codeine metabolism is impaired.
Pharmacology
Mechanism of Action
Guaifenesin acts as an expectorant by increasing the volume and decreasing the viscosity of respiratory tract secretions, thereby facilitating their removal by ciliary action and coughing. Codeine acts as an antitussive by directly suppressing the cough reflex in the medulla oblongata. It is an opioid agonist, binding to mu-opioid receptors in the central nervous system.
Pharmacokinetics
Absorption:
Bioavailability:
Codeine: ~50-70% (oral); Guaifenesin: Readily absorbed
Tmax:
Codeine: 0.5-1 hour; Guaifenesin: ~1 hour
FoodEffect:
Food may delay absorption but not significantly alter extent.
Distribution:
Vd:
Codeine: 2.5 L/kg; Guaifenesin: Not well-defined, widely distributed
ProteinBinding:
Codeine: ~7-25%; Guaifenesin: Not significant
CnssPenetration:
Codeine: Yes; Guaifenesin: Limited
Elimination:
HalfLife:
Codeine: 2.5-3 hours; Guaifenesin: ~1 hour
Clearance:
Not available
ExcretionRoute:
Codeine: Primarily renal (urine) as metabolites (morphine, norcodeine, and their glucuronides); Guaifenesin: Primarily renal (urine) as metabolites
Unchanged:
Codeine: ~10% unchanged in urine; Guaifenesin: <1% unchanged in urine
Pharmacodynamics
OnsetOfAction:
Codeine: 30-60 minutes (antitussive); Guaifenesin: 30 minutes
PeakEffect:
Codeine: 1-2 hours; Guaifenesin: 1-2 hours
DurationOfAction:
Codeine: 4-6 hours; Guaifenesin: 4-6 hours
Safety & Warnings
BLACK BOX WARNING
WARNING: RISKS FROM CONCOMITANT USE WITH BENZODIAZEPINES OR OTHER CNS DEPRESSANTS; ADDICTION, ABUSE, AND MISUSE; RESPIRATORY DEPRESSION; ACCIDENTAL INGESTION; NEONATAL OPIOID WITHDRAWAL SYNDROME; CYP2D6 ULTRA-RAPID METABOLISM OF CODEINE; and RISKS IN ADOLESCENTS AND CHILDREN. Concomitant use of opioids with benzodiazepines or other CNS depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. Reserve concomitant prescribing for use in patients for whom alternative treatment options are inadequate. Codeine-containing products expose patients and other users to the risks of opioid addiction, abuse, and misuse, which can lead to overdose and death. Serious, life-threatening, or fatal respiratory depression may occur. Accidental ingestion of even one dose can cause a fatal overdose. Prolonged use during pregnancy can result in neonatal opioid withdrawal syndrome. Respiratory depression and death have occurred in children who received codeine, most often after tonsillectomy and/or adenoidectomy, and in some cases, were ultra-rapid metabolizers of codeine due to a CYP2D6 polymorphism. Codeine is contraindicated in children younger than 12 years of age and in adolescents 12 to 18 years of age who have obesity or severe sleep apnea or who have undergone tonsillectomy or adenoidectomy.
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Severe dizziness or fainting
Chest pain or pressure, rapid heartbeat, or irregular heartbeat
Breathing difficulties, slow breathing, or shallow breathing
Noisy breathing
Sleep apnea (breathing problems during sleep)
Confusion
Hallucinations (seeing or hearing things that are not there)
Mood changes
Seizures
Severe headache
Urination difficulties
Shakiness
Changes in vision
Severe constipation or stomach pain, which may indicate a severe bowel problem
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other symptoms that bother you or persist, contact your doctor:
Constipation
Upset stomach or vomiting
Dizziness, drowsiness, fatigue, or weakness
* Excessive sweating
This is not an exhaustive list of possible side effects. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Severe dizziness or fainting
Chest pain or pressure, rapid heartbeat, or irregular heartbeat
Breathing difficulties, slow breathing, or shallow breathing
Noisy breathing
Sleep apnea (breathing problems during sleep)
Confusion
Hallucinations (seeing or hearing things that are not there)
Mood changes
Seizures
Severe headache
Urination difficulties
Shakiness
Changes in vision
Severe constipation or stomach pain, which may indicate a severe bowel problem
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other symptoms that bother you or persist, contact your doctor:
Constipation
Upset stomach or vomiting
Dizziness, drowsiness, fatigue, or weakness
* Excessive sweating
This is not an exhaustive list of possible side effects. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Slow, shallow, or difficult breathing
- Extreme drowsiness or dizziness
- Confusion or unusual thoughts
- Severe constipation or abdominal pain
- Signs of an allergic reaction (rash, itching, swelling, severe dizziness, trouble breathing)
- Bluish lips or skin
- Fainting
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances. Be sure to describe the allergic reaction and its symptoms.
Certain health conditions, such as:
+ Respiratory problems, including asthma, breathing difficulties, or sleep apnea
+ Elevated carbon dioxide levels in the blood
+ Stomach or bowel obstruction or narrowing
Respiratory issues, including:
+ A cough producing excessive mucus
+ A chronic cough caused by smoking or exposure to smoke
+ Lung conditions like asthma or emphysema
Recent use (within the last 14 days) of specific medications for depression or Parkinson's disease, including isocarboxazid, phenelzine, tranylcypromine, selegiline, or rasagiline, as this may lead to severely high blood pressure
Current use of certain medications, such as buprenorphine, butorphanol, linezolid, methylene blue, nalbuphine, or pentazocine
If your doctor has informed you that you are a rapid metabolizer of certain medications
* If you are breastfeeding, as you should not breastfeed while taking this medication
This list is not exhaustive, and it is crucial to inform your doctor and pharmacist about all your medications (prescription, over-the-counter, natural products, and vitamins) and health conditions to ensure safe use. Do not initiate, stop, or modify the dosage of any medication without consulting your doctor.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances. Be sure to describe the allergic reaction and its symptoms.
Certain health conditions, such as:
+ Respiratory problems, including asthma, breathing difficulties, or sleep apnea
+ Elevated carbon dioxide levels in the blood
+ Stomach or bowel obstruction or narrowing
Respiratory issues, including:
+ A cough producing excessive mucus
+ A chronic cough caused by smoking or exposure to smoke
+ Lung conditions like asthma or emphysema
Recent use (within the last 14 days) of specific medications for depression or Parkinson's disease, including isocarboxazid, phenelzine, tranylcypromine, selegiline, or rasagiline, as this may lead to severely high blood pressure
Current use of certain medications, such as buprenorphine, butorphanol, linezolid, methylene blue, nalbuphine, or pentazocine
If your doctor has informed you that you are a rapid metabolizer of certain medications
* If you are breastfeeding, as you should not breastfeed while taking this medication
This list is not exhaustive, and it is crucial to inform your doctor and pharmacist about all your medications (prescription, over-the-counter, natural products, and vitamins) and health conditions to ensure safe use. Do not initiate, stop, or modify the dosage of any medication without consulting your doctor.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. Adhere strictly to the dosage instructions provided by your doctor, as taking more than prescribed can increase the risk of severe side effects. Do not exceed the recommended duration of use, and only take this medication for the length of time specified by your doctor.
To minimize the risk of accidents, avoid driving and other activities that require alertness until you understand how this medication affects you. When rising from a sitting or lying position, do so slowly to reduce the likelihood of dizziness or fainting. Be cautious when navigating stairs.
Long-term use of this medication can lead to dependence. If you have been taking this medication regularly and stop suddenly, you may experience withdrawal symptoms. Do not discontinue use without consulting your doctor first, and report any adverse effects to your doctor promptly.
Before taking this medication with other strong pain relievers or using a pain patch, consult your doctor to avoid potential interactions. Additionally, this medication may interfere with certain laboratory tests, so inform all your healthcare providers and laboratory personnel that you are taking this medication.
Keep this medication out of reach of children, as accidental ingestion can be fatal. If a child accidentally takes this medication, seek immediate medical attention.
If you are 65 years or older, exercise caution when taking this medication, as you may be more susceptible to side effects. Children, particularly those with pre-existing breathing problems, are at a higher risk of severe side effects, including life-threatening respiratory issues. Discuss these risks with your doctor.
Using this medication during pregnancy can harm the unborn baby. If you become pregnant or are already pregnant, notify your doctor immediately. Prolonged use during pregnancy can lead to withdrawal symptoms in the newborn, which can be life-threatening if left untreated.
To minimize the risk of accidents, avoid driving and other activities that require alertness until you understand how this medication affects you. When rising from a sitting or lying position, do so slowly to reduce the likelihood of dizziness or fainting. Be cautious when navigating stairs.
Long-term use of this medication can lead to dependence. If you have been taking this medication regularly and stop suddenly, you may experience withdrawal symptoms. Do not discontinue use without consulting your doctor first, and report any adverse effects to your doctor promptly.
Before taking this medication with other strong pain relievers or using a pain patch, consult your doctor to avoid potential interactions. Additionally, this medication may interfere with certain laboratory tests, so inform all your healthcare providers and laboratory personnel that you are taking this medication.
Keep this medication out of reach of children, as accidental ingestion can be fatal. If a child accidentally takes this medication, seek immediate medical attention.
If you are 65 years or older, exercise caution when taking this medication, as you may be more susceptible to side effects. Children, particularly those with pre-existing breathing problems, are at a higher risk of severe side effects, including life-threatening respiratory issues. Discuss these risks with your doctor.
Using this medication during pregnancy can harm the unborn baby. If you become pregnant or are already pregnant, notify your doctor immediately. Prolonged use during pregnancy can lead to withdrawal symptoms in the newborn, which can be life-threatening if left untreated.
Overdose Information
Overdose Symptoms:
- Slowed or stopped breathing
- Extreme drowsiness or inability to wake up
- Pinpoint pupils
- Limp muscles
- Cold, clammy skin
- Bluish lips or fingernails
- Loss of consciousness
What to Do:
Seek immediate emergency medical attention. Call 911 or your local emergency number. If the person has collapsed, is not breathing, or is having a seizure, call 911. For less severe symptoms, call Poison Control at 1-800-222-1222.
Drug Interactions
Contraindicated Interactions
Major Interactions
- CNS depressants (e.g., alcohol, benzodiazepines, other opioids, sedatives, hypnotics, tricyclic antidepressants, phenothiazines, general anesthetics): Increased risk of respiratory depression, profound sedation, coma, and death.
- Monoamine Oxidase Inhibitors (MAOIs): Concomitant use or within 14 days of MAOI discontinuation can lead to severe, unpredictable reactions (e.g., serotonin syndrome, respiratory depression).
- CYP2D6 inhibitors (e.g., fluoxetine, paroxetine, quinidine, bupropion): May decrease conversion of codeine to morphine, reducing efficacy.
- CYP2D6 inducers (e.g., rifampin, carbamazepine, phenytoin): May increase conversion of codeine to morphine, increasing risk of toxicity.
Moderate Interactions
- Serotonergic drugs (e.g., SSRIs, SNRIs, triptans, tramadol): Increased risk of serotonin syndrome.
- Anticholinergic drugs (e.g., atropine, scopolamine, some antihistamines): Increased risk of urinary retention and severe constipation.
- Muscle relaxants: Increased risk of respiratory depression and sedation.
- Diuretics: Opioids may reduce the efficacy of diuretics by inducing the release of antidiuretic hormone.
Minor Interactions
- Not significant for guaifenesin.
Monitoring
Baseline Monitoring
Respiratory rate and depth
Rationale: To establish baseline and identify risk for respiratory depression, especially with codeine.
Timing: Prior to initiation
Level of consciousness/sedation
Rationale: To establish baseline and identify risk for excessive sedation.
Timing: Prior to initiation
Cough frequency and severity
Rationale: To assess the need for antitussive therapy and later evaluate efficacy.
Timing: Prior to initiation
Routine Monitoring
Respiratory rate and depth
Frequency: Periodically during therapy, especially after dose adjustments or with concomitant CNS depressants.
Target: Normal for age (e.g., 12-20 breaths/min for adults)
Action Threshold: <10 breaths/min or shallow breathing; consider naloxone if severe.
Level of consciousness/sedation
Frequency: Periodically during therapy.
Target: Alert and oriented, mild sedation acceptable if not impairing function.
Action Threshold: Excessive drowsiness, difficulty arousing, confusion; reduce dose or discontinue.
Bowel function
Frequency: Daily
Target: Regular bowel movements
Action Threshold: Constipation; initiate bowel regimen.
Cough relief
Frequency: Daily
Target: Acceptable reduction in cough frequency/severity
Action Threshold: No improvement or worsening; re-evaluate therapy.
Symptom Monitoring
- Dizziness
- Nausea/Vomiting
- Constipation
- Drowsiness
- Lightheadedness
- Shortness of breath
- Slow or shallow breathing
- Confusion
- Pinpoint pupils
- Unusual sleepiness
Special Patient Groups
Pregnancy
Category C. Codeine crosses the placenta. Prolonged use during pregnancy can lead to neonatal opioid withdrawal syndrome (NOWS) in the newborn, characterized by irritability, hyperactivity, abnormal sleep pattern, high-pitched cry, tremor, vomiting, diarrhea, and failure to gain weight. Use only if the potential benefit justifies the potential risk to the fetus.
Trimester-Specific Risks:
First Trimester:
Potential for congenital malformations (e.g., neural tube defects, cardiac defects) with opioid exposure, though data for codeine are mixed and not conclusive.
Second Trimester:
Risk of NOWS increases with prolonged use.
Third Trimester:
Highest risk of NOWS with prolonged use. Risk of respiratory depression in the neonate if used close to delivery.
Lactation
Contraindicated in breastfeeding mothers. Codeine and its active metabolite, morphine, are excreted in breast milk. In mothers who are ultra-rapid metabolizers of codeine, potentially fatal levels of morphine can be produced, leading to serious adverse reactions, including respiratory depression and death, in breastfed infants. Even at normal doses, infants can experience sedation, difficulty feeding, and respiratory depression.
Infant Risk:
L4 (Possibly hazardous). High risk of serious adverse effects including respiratory depression, sedation, and death, especially in infants of ultra-rapid metabolizer mothers.
Pediatric Use
Contraindicated in children younger than 12 years of age. Contraindicated in adolescents 12 to 18 years of age who have obesity or severe sleep apnea or who have undergone tonsillectomy or adenoidectomy due to increased risk of respiratory depression. Use in other adolescents 12-18 years should be with extreme caution and only if benefits outweigh risks.
Geriatric Use
Use with caution in elderly patients. They may be more sensitive to the respiratory depressant and CNS effects of codeine. Start with lower doses and titrate slowly. Monitor closely for sedation, respiratory depression, and constipation. Renal and hepatic impairment are more common in the elderly, requiring dose adjustments.
Clinical Information
Clinical Pearls
- Due to the risks associated with codeine, especially in pediatric and breastfeeding populations, this combination product should be used with extreme caution and only when alternative therapies are inadequate.
- Educate patients on the signs of respiratory depression and overdose, and the importance of avoiding alcohol and other CNS depressants.
- Constipation is a common side effect of codeine; advise patients on preventative measures (fiber, fluids) and consider prophylactic laxatives.
- The antitussive effect of codeine is dose-dependent and can be associated with significant side effects. Guaifenesin's efficacy as an expectorant is enhanced by adequate hydration.
- Always assess the underlying cause of the cough; this product is for symptomatic relief only.
Alternative Therapies
- Dextromethorphan (antitussive)
- Benzonatate (antitussive)
- Guaifenesin (expectorant, single agent)
- Humidifiers and saline nasal sprays (non-pharmacologic)
- Honey (for cough relief)
Cost & Coverage
Average Cost:
Varies widely, typically $20-$50 per 120 mL or 473 mL bottle
Generic Available:
Yes
Insurance Coverage:
Tier 2 or 3 (often requires prior authorization or step therapy due to codeine)
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so it's a good idea to check with your pharmacist for more information. If you have any questions or concerns about your medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it happened.