What is Guaifenesin-Codeine? Uses, warnings & side effects

Your doctor will tell you how much medicine to use. Do not use more than directed.

Take a dose every four hours.

Do not take more than six doses in 24 hours.

Measure the oral liquid medicine with a marked measuring spoon, oral syringe, or medicine cup.

Store in a closed container at room temperature. Keep this medicine protected from heat.

If you miss a dose or forget to take your medicine, take it as soon as you can. 

If it is almost time for your next dose, wait until then to take the medicine and skip the missed dose.

If you take a missed dose, take the next dose four hours later.

Do not use extra medicine to make up for a missed dose.

This medicine is not right for everyone. 

You should not use this medicine if you have had an allergic reaction to codeine or guaifenesin, or if you have:

• Severe breathing problems, including acute bronchial asthma or respiratory depression (slow or shallow breathing)

• Gastrointestinal blockage or narrowing

This medicine should never be given to a child younger than 12.

Tell any doctor or other healthcare provider who treats you that you are using this medicine.

Keep all appointments with the prescribing healthcare provider.

Before taking guaifenesin-codeine, make sure the prescriber knows if you are pregnant, breastfeeding, or have:

• Asthma or other breathing or lung problems

• Persistent cough

• A cough accompanied by excessive phlegm

• Liver problems

• Kidney problems

• Thyroid problems

• Head injury

• A history of seizures

• Stomach or intestinal disorders

• Pancreas problems

• Gallbladder problems

• Trouble urinating

• A history of mental illness, alcohol abuse, or drug abuse

This medicine can cause serious side effects, including:

• Slowed or stopped breathing

• Seizures

• Serotonin syndrome

• Severe allergic reactions

This medicine may cause constipation. Ask the doctor before you use a laxative to manage any constipation you experience.

This medicine may be habit-forming. If you feel that the medicine is not working, do not take more than your prescribed dose. Call the prescriber.

Do not take more than the prescribed dose. An overdose could be serious or life-threatening. Symptoms of an overdose include extreme dizziness or weakness, shortness of breath, slow heartbeat, seizures, and cold, clammy skin.

This medicine may make you dizzy or drowsy. Avoid driving, using machines, or doing anything else that could be dangerous if you are not alert.

Women who are pregnant or breastfeeding should avoid using codeine because of possible serious side effects to the baby.

Codeine is a federally controlled substance. Giving or selling this medication to anyone else is dangerous and illegal.

Keep this medicine out of sight and reach of children and other people.

Do not take this medicine with monoamine oxidase inhibitors (MAOIs). These drugs must be stopped at least 14 days before you can safely take guaifenesin-codeine.

Tell the prescriber about all prescription drugs, over-the-counter medications, and supplements being taken, particularly:

• Other opioids

• Drugs that make you sleepy, such as benzodiazepines, sleeping pills, antihistamines, anxiety medications, antipsychotics, muscle relaxants, and alcohol

• Drugs that treat mental health conditions, such as antidepressants, antipsychotics, and anxiety medications

• Drugs that treat migraines, called triptans

• Macrolide antibiotics such as erythromycin

• Azole antifungal drugs such as ketoconazole

• Antiviral drugs called protease inhibitors

• Carbamazepine, Paxlovid, phenytoin, quinidine, rifampin

Do not drink alcohol while you are using this medicine.

Make sure any doctor or other healthcare provider who treats you knows that you are using this medicine before they prescribe new medications.