Drugs & Medications – Guaifenesin Oral

Similar medicines derived from the guaiac tree were in use as a generic remedy by Native Americans when explorers reached North America in the 1500s, but guaifenesin was first approved by the Food and Drug Administration (FDA) in 1952.

Guaifenesin Oral Uses

Guaifenesin is used to treat coughs and congestion caused by the common cold, bronchitis, and other breathing illnesses. This product is usually not used for ongoing cough from smoking or long-term breathing problems (such as chronic bronchitis, emphysema) unless directed by your doctor. Guaifenesin is an expectorant. It works by thinning and loosening mucus in the airways, clearing congestion, and making breathing easier.

If you are self-treating with this medication, it is important to read the package instructions carefully before you start using this product to be sure it is right for you. (See also Precautions section.)

Cough-and-cold products have not been shown to be safe or effective in children younger than 6 years. Therefore, do not use this product to treat cold symptoms in children younger than 6 years unless specifically directed by the doctor. Some products (such as long-acting tablets/capsules) are not recommended for use in children younger than 12 years. Ask your doctor or pharmacist for more details about using your product safely.

These products do not cure or shorten the length of the common cold. To decrease the risk for side effects, carefully follow all dosage directions. Do not give other cough-and-cold medication that might contain the same or similar ingredients (see also Drug Interactions section). Ask the doctor or pharmacist about other ways to relieve cough and cold symptoms (such as drinking enough fluids, using a humidifier or saline nose drops/spray).

How to use guaifenesin Oral

Take this medication by mouth with or without food, as directed by your doctor, usually every 4 hours. If you are self-treating, follow all directions on the product package. If you are uncertain about any of the information, ask your doctor or pharmacist.

Guaifenesin may have a bitter taste. Do not split the tablets unless they have a score line and your doctor or pharmacist tells you to do so. Swallow the whole or split tablet without crushing or chewing.

If you are using the liquid form of this medication, carefully measure the dose using a special measuring device/spoon. Do not use a household spoon because you may not get the correct dose.

For powder packets, empty the entire contents of the packet onto the tongue and swallow. To prevent a bitter taste, do not chew.

Dosage is based on your age, medical condition, and response to treatment. Do not take more than 6 doses in a day. Do not increase your dose or take this drug more often than directed.

Drink plenty of fluids while taking this medication. Fluids will help to break up mucus and clear congestion.

Tell your doctor if your cough is accompanied by fever, severe sore throat, rash, persistent headache, or if it persists, returns, or worsens after 7 days. These may be signs of a serious medical problem. Seek immediate medical attention if you think you may have a serious medical problem.

Guaifenesin Oral Side Effects

Nausea or vomiting may occur. If either of these effects persist or worsen, tell your doctor or pharmacist promptly.

If your doctor has directed you to use this medication, remember that he or she has judged that the benefit to you is greater than the risk of side effects. Most people using this medication do not have serious side effects.

A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

Guaifenesin Oral Precautions

Before taking this medication, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: breathing problems (such as emphysema, chronic bronchitis, asthma, smoker’s cough), cough with blood or large amounts of mucus.

Liquid forms of this product may contain sugar and/or alcohol. Caution is advised if you have diabetes, liver disease, or any other condition that requires you to limit/avoid these substances in your diet. Ask your doctor or pharmacist about using this product safely

The liquid forms and powder packets of this medication may contain aspartame. If you have phenylketonuria (PKU) or any other condition that requires you to restrict your intake of aspartame (or phenylalanine), consult your doctor or pharmacist about using this product safely.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

It is unknown if guaifenesin passes into breast milk. Discuss the risks and benefits with your doctor before breast-feeding.

Guaifenesin Oral Interactions

The effects of some drugs can change if you take other drugs or herbal products at the same time. This can increase your risk for serious side effects or may cause your medications not to work correctly. These drug interactions are possible, but do not always occur. Your doctor or pharmacist can often prevent or manage interactions by changing how you use your medications or by close monitoring.

The effects of some drugs can change if you take other drugs or herbal products at the same time. This can increase your risk for serious side effects or may cause your medications not to work correctly. These drug interactions are possible, but do not always occur. Your doctor or pharmacist can often prevent or manage interactions by changing how you use your medications or by close monitoring.

Guaifenesin is available in both prescription and nonprescription products. Check the labels of all your medications to make sure you are not taking more than one product containing guaifenesin.

This product can affect the results of certain lab tests (such as urine levels of certain acids). Make sure laboratory personnel and all your doctors know you use this drug.

Guaifenesin Oral Overdose

If overdose is suspected, contact a poison control center or emergency room immediately. US residents can call the US National Poison Hotline at 800-846-5425. Canada residents can call a provincial poison control center.


If your doctor prescribed this medication, do not share this medication with others.

Keep all regular medical and laboratory appointments.

This medication is for temporary use only. Do not take this medication for more than 7 days unless your doctor tells you to do so. Tell your doctor if your condition lasts longer than 7 days.

Missed Dose:

If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up.


Store at room temperature away from light and moisture. Do not store in the bathroom. Do not freeze liquid forms of this medication. Different brands of this medication have different storage needs. Check the product package for instructions on how to store your brand, or ask your pharmacist. Keep all medications away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company for more details about how to safely discard your product.

Guaifenesin side effects

Guaifenesin is a type of drug called an expectorant, meaning it loosens phlegm and increases the lubrication inside the lungs, allowing for a more productive cough and therefore, less chest congestion. The over-the-counter version of guaifenesin is Mucinex. Chest congestion can have different causes—allergies, sinus infection, the common cold—but guaifenesin can help in any case. While for the most part the side effects of this medication are mild, it is still good to know about and consider them so you can make a well-informed decision about taking the guaifenesin; it is also good to know when or if you should seek medical attention. This article will lay it all out for you. Learn about the side effects and more of guaifenesin.

Side Effects

This type of medication does not typically produce any serious side effects, but that’s not to say they can’t happen. Everybody reacts differently; most just don’t react in a negative way at all.

Allergic Reaction

If you experience any signs of an allergic reaction—difficulty breathing, closing of the throat, swelling of the lips, tongue, or face, or hives—it is extremely important that you seek medical attention and stop taking guaifenesin immediately.

Other Serious Side Effects

While the following side effects are rare, they are quite serious. If they occur, it is best to seek medical attention immediately and stop taking the medication so no further complications arise: difficulty urinating, fast or irregular heartbeat, hallucinations, seizures, severe dizziness, severe lightheadedness, severe headache, or tremors.

Other Less Serious Side Effects

Less serious side effects that can come about include dizziness, headache, excitability, nervousness, anxiety, trouble sleeping, weakness, constipation, mild and temporary changes in behavior, drowsiness, a rash, nausea, vomiting, and/or stomach upset. If any of these are experienced, it is okay to continue taking the medication, but it is something that you should discuss with your doctor.

Drug Interactions

It is also possible that side effects may occur when guaifenesin is taken with other medications. Always talk to your doctor about the other medications that you’re taking or even any herbal supplements that you may take while on guaifenesin.

Certain Medical Conditions

Pregnant women should not take this medication unless told to do so by a doctor; currently, it is not known how this medication will affect the fetus. Also, if you smoke or have asthma, chronic bronchitis, or emphysema talk with a doctor or pharmacist before taking this medication; otherwise, you could be at a greater risk for having certain side effects.

Other Important Information

Many times side effects can occur because the medication, in this case guaifenesin, is not taken properly. Always take the medication as directed by your doctor; don’t crush or chew the tablet. With each dose, drink a full glass of water. As a side note, drinking fluids while taking this medication will certainly do you some good because the fluids will help with chest congestion. If you discover that guaifenesin upsets your stomach, take the medication with food. If you take the liquid version, don’t guesstimate how much you’re taking by using a tablespoon; it is important that you get a dose-measuring spoon or cup so you’re getting the correct dose. If you happen to miss a dose, don’t take it if you’re getting close to the next dosage time; don’t EVER double the dose. An overdose is not likely to occur, but if you suspect one, seek medical attention. Lastly, stop the use of this medication if your cough lasts for more than 7 days, if your cough returns, or if your cough is accompanied by a fever, rash, or persistent headache.