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Overview: Codeine/guaifenesin is a combination medicine used to reduce coughing and loosen mucus from the common cold or allergies. It works by affecting the part of the brain that controls the cough reflex and thins mucus by increasing the amount of fluid in your airways, making it easier to clear out. Common side effects may include constipation and drowsiness. Before using codeine/guaifenesin, make sure to tell your healthcare provider about any health conditions or medicines you are taking.

Uses

What is codeine/guaifenesin used for?

Codeine/guaifenesin is commonly used to reduce coughing and loosen mucus from the common cold or allergies.

Codeine/guaifenesin may also be used for other conditions as determined by your healthcare provider.

How does codeine/guaifenesin work (mechanism of action)?

Codeine reduces the urge to cough by affecting the part of the brain that controls the cough reflex. Guaifenesin thins mucus by increasing the amount of fluid in your airways, making it easier to clear out.

How is codeine/guaifenesin supplied (dosage forms)?

Brands and other names

  • Cheratussin AC
  • Guaiatussin AC
  • Guaifenesin AC
  • Iophen C-NR
  • Robitussin AC
  • Virtussin AC

Dosage forms and strengths

  • 10 mg/100 mg per 5 mL oral solution

How should I store codeine/guaifenesin?

Codeine/guaifenesin should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place. 

Side Effects

What are the most common side effects of codeine/guaifenesin?

The most common side effects of codeine/guaifenesin are constipation and drowsiness. Tell your healthcare provider if you have any of these side effects that bother you.

There may be other side effects of codeine/guaifenesin that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of codeine/guaifenesin?

While less common, the most serious side effects of codeine/guaifenesin are described below, along with what to do if they happen.

Severe Allergic Reactions. Codeine/guaifenesin may cause allergic reactions, which can be serious. Stop taking codeine/guaifenesin and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Warnings & Precautions

Who should not use codeine/guaifenesin?

Allergies to Ingredients. People who are allergic to any of the following should not take codeine/guaifenesin.

  • Codeine
  • Guaifenesin
  • Cheratussin AC
  • Guaiatussin AC
  • Guaifenesin AC
  • Iophen C-NR
  • Robitussin AC
  • Virtussin AC
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific codeine/guaifenesin products they stock.

What should I know about codeine/guaifenesin before using it?

Do not take codeine/guaifenesin unless it has been prescribed or recommended to you by a healthcare provider. Take it as prescribed.

Do not share codeine/guaifenesin with other people, even if they have the same condition as you. It may harm them.

Keep codeine/guaifenesin out of the reach of children. Codeine/guaifenesin is a controlled substance because it can be misused or lead to dependence. Store codeine/guaifenesin in a safe place to protect it from theft. It is illegal to sell or give away this medicine.

Use an accurate measuring device to measure your dose of codeine/guaifenesin. A household spoon is not an accurate measuring device and may cause you to take the wrong dose. Ask your pharmacist to recommend an appropriate measuring device.

Codeine/guaifenesin can affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how codeine/guaifenesin affects you.

Tell your healthcare provider if your cough does not get better after seven days of taking codeine/guaifenesin. They will need to check to see if something else is causing the cough. 

What should I tell my healthcare provider before using codeine/guaifenesin?

Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if codeine/guaifenesin is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your healthcare provider if you have any of the following. 

  • A persistent cough 
  • Coughing up excessive amounts of mucus 
  • Breathing problems, such as asthma or chronic obstructive pulmonary disease (COPD)
  • Fever and rash or persistent headache

Other Medicines and Supplements. Codeine/guaifenesin may interact with other medicines and supplements. Before taking codeine/guaifenesin, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. Tell your healthcare provider if you are or plan to become pregnant. Your healthcare provider will advise you if you should take codeine/guaifenesin while you are pregnant or trying to get pregnant.

Breastfeeding. Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Your healthcare provider will advise you if you should take codeine/guaifenesin while breastfeeding.

Interactions

Does codeine/guaifenesin interact with foods or drinks?

There are no known interactions between codeine/guaifenesin and foods or drinks.

It is unknown if drinking alcohol will affect codeine/guaifenesin. The risk of drowsiness may be increased if you drink alcohol while taking codeine/guaifenesin.

Does codeine/guaifenesin interact with other medicines (drug interactions)?

Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking codeine/guaifenesin.

  • A monoamine oxidase inhibitor (MAOI), which is a medicine usually used for depression or Parkinson’s disease
  • A medicine for depression
  • Any medicine that causes dizziness and sleepiness, such as prescription pain medicines, sleep medicines, and medicines for anxiety

This may not be a complete list of medicines that can interact with codeine/guaifenesin. Always check with your healthcare provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much codeine/guaifenesin?

If you or someone else has used too much codeine/guaifenesin, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of codeine/guaifenesin?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.