Key takeaways:
Guaifenesin (Mucinex) is an over-the-counter (OTC) product that can help relieve chest congestion or a productive (wet) cough.
A common immediate-release guaifenesin dosage for adults is 200 mg to 400 mg by mouth every 4 hours as needed. A common extended-release guaifenesin dosage is 600 mg to 1,200 mg by mouth every 12 hours as needed.
Children’s guaifenesin dosages are based on the child’s age. You can give guaifenesin liquid to children younger than 12 years old.
Guaifenesin is available as a brand-name medication. But you can also find it as a lower-cost generic. If your prescriber writes you a prescription for OTC guaifenesin, GoodRx can help save you money.
Save on related medications
Guaifenesin is a common over-the-counter (OTC) cough medication that goes by many brand names. Some examples include Mucinex and Geri-Tussin. It’s also available as a generic medication.
Guaifenesin is an expectorant. This means it helps make it easier to cough up mucus and clear up chest congestion. Guaifenesin is often included with other medications in combination cold products.
With guaifenesin in many OTC cold medicines, it’s important to know how much is safe to take. Let’s review the typical adult and children’s guaifenesin dosages.
Note: This article focuses on dosages for products that only contain guaifenesin — not combination products, such as Mucinex DM (guaifenesin / dextromethorphan). Check out GoodRx’s Mucinex DM dosage article for more information.
What guaifenesin dosage forms are available?
Guaifenesin comes in many different dosage forms. The amount of guaifenesin per dose varies depending on the product.
Dosage form | Amount of guaifenesin | How often can you take it? |
|---|---|---|
600 mg or 1,200 mg per tablet | Every 12 hours as needed | |
Immediate-release (IR) tablets | 200 mg or 400 mg per tablet | Every 4 hours as needed |
Oral liquid | 100 mg per 5 mL | Every 4 hours as needed |
Always read the instructions on the label carefully before taking guaifenesin. Use the provided dosing cup if you’re taking guaifenesin oral liquid. Or ask your pharmacist for a dosing device, such as an oral syringe or measuring cup, to measure the liquid.
As mentioned above, many combination cold products have guaifenesin in them. Ask a healthcare professional before taking more than one cold medicine. It’s easy to accidentally take too much guaifenesin by taking multiple products.
What’s the typical guaifenesin dosage for adults?
Guaifenesin is made by many different manufacturers, and the dose may vary between products. When deciding on an OTC guaifenesin product, review the label to see how much guaifenesin is in each dose. Be sure to include guaifenesin from all sources.
Guaifenesin ER tablets, such as Mucinex maximum strength
Guaifenesin ER is the only standalone guaifenesin product sold under the brand name Mucinex. There are two different guaifenesin ER tablets available. And the recommended guaifenesin ER dosage depends on which version you’re taking.
Mucinex regular strength dosage (600 mg tablets): Take 1 to 2 tablets (600 to 1,200 mg) by mouth with a full glass of water every 12 hours as needed. Don’t take more than 4 tablets (2,400 mg) in 24 hours.
Mucinex maximum strength dosage (1,200 mg tablets): Take 1 tablet (1,200 mg) by mouth every 12 hours with a full glass of water as needed. Don’t take more than 2 tablets (2,400 mg) in 24 hours.
Good to know: Guaifenesin ER tablets release medication slowly over 12 hours. You shouldn’t cut, chew, or crush these tablets. Doing so can cause the tablet to release the medication too quickly, potentially causing more side effects. Your dose may also wear off sooner.
Guaifenesin IR tablets
Like the ER tablets, there are two versions of guaifenesin IR tablets: 200 mg and 400 mg tablets. And the dosage depends on which one you’re taking.
Guaifenesin IR 200 mg dosage: Take 1 to 2 tablets (200 mg to 400 mg) by mouth every 4 hours. Don’t take more than 12 tablets (2,400 mg) in 24 hours.
What to expect: Following recommended guaifenesin (Mucinex) dosages can help limit side effects. Learn about possible side effects and how to manage them here.
What’s the best over-the-counter cold medication? Our experts provide tips for finding the best over-the-counter cold or flu medication based on your symptoms.
Does guaifenesin work? While some people experience benefits, there’s not much evidence to show that guaifenesin is effective for cold and flu symptoms.
Guaifenesin IR 400 mg dosage: Take 1 tablet (400 mg) by mouth with a full glass of water every 4 hours. Don’t take more than 6 tablets (2,400 mg) in 24 hours.
Guaifenesin oral liquid
The adult guaifenesin liquid dosage is 10 mL to 20 mL (200 mg to 400 mg) by mouth every 4 hours. Don’t take more than 6 doses (up to 2,400 mg) in 24 hours.
What’s the typical children’s Mucinex dosage?
There are no brand-name Mucinex products labeled as “children’s Mucinex” that only contain guaifenesin. Brand-name Children’s Mucinex products contain guaifenesin and at least one other active ingredient. But there are generic guaifenesin-only products that have children’s dosage instructions on them.
Certain forms of guaifenesin can be safely given to children as young as age 2. Children ages 12 and older can follow the adult guaifenesin dosage instructions for all the products discussed above. Don’t give children under age 12 guaifenesin ER or IR tablets. Ask a healthcare professional for help if you don’t see a dose for your child’s age listed on the package instructions.
Guaifenesin oral liquid
Guaifenesin oral liquid can be given to children ages 2 and older. Children’s guaifenesin liquid dosages depend on your child’s age. Below is a handy table to help you find the right dosage. But always ask a healthcare professional if you’re unsure how much to give your child.
Child’s age | Guaifenesin dosage | Maximum daily dose |
|---|---|---|
2 to 6 years | 2.5 mL (50 mg) to 5 mL (100 mg) every 4 hours | Don’t give more than 6 doses (up to 600 mg) in 24 hours |
6 to 12 years | 5 mL (100 mg) to 10 mL (200 mg) every 4 hours | Don’t give more than 6 doses (up to 1,200 mg) in 24 hours |
12 years or older | 10 mL (200 mg) to 20 mL (400 mg) every 4 hours | Don’t give more than 6 doses (up to 2,400 mg) in 24 hours |
Can adults take children's Mucinex?
Yes, adults can take children’s Mucinex. Children’s guaifenesin products typically include a dosage for people ages 12 and older, as listed in the table above. You’ll want to look for that age range on the directions section of the OTC label. This could be worded as “ages 12 years and older” or “adults and children 12 years and older.”
If you’re unsure about how much to take, ask your pharmacist.
Are there any dosage adjustments for medical conditions?
In general, there are no special guaifenesin dosage adjustments for people with kidney or liver problems. But there are people who should speak with a healthcare professional before taking it.
These include people who:
Have a chronic cough caused by smoking, asthma, or chronic obstructive pulmonary disease (COPD)
Are pregnant
Are allergic to artificial sweeteners
Have severe kidney disease
Have diabetes
The above health conditions don’t always mean you can’t take any guaifenesin products. But you may need to avoid certain formulations, or your healthcare team may want to follow up with you while taking it.
What happens if you miss a dose of guaifenesin?
Guaifenesin is an as needed medication. This means that you only take it when you have symptoms. But it’s important to wait the required amount of time between doses. Make sure there’s at least 4 hours between doses of guaifenesin IR tablets and oral liquid. And wait at least 12 hours between doses of guaifenesin ER tablets.
What happens if you take too much Mucinex?
Mucinex is very well tolerated. Many people experience no side effects when taking it as directed. But taking too much Mucinex can cause side effects such as upset stomach, dizziness, and headaches. So taking an extra dose by mistake is unlikely to seriously harm you.
Mucinex overdoses are typically only seen when people are taking combination Mucinex products, such as Mucinex DM. And the potential overdose symptoms, such as hallucinations and trouble breathing, are likely due to the dextromethorphan component of these products — not the guaifenesin.
Still, you should only take the recommended dosages of guaifenesin. If you suspect that you or someone you know has taken too much guaifenesin and you’re concerned, contact a healthcare professional or call Poison Control at 1-800-222-1222.
How to save on guaifenesin
There are many ways to save on guaifenesin, which is available as both a brand-name and generic medication. By having your prescriber write a prescription for OTC guaifenesin, GoodRx can help you save over 70% off the average retail price. Guaifenesin ER’s price at certain pharmacies is as low as $10.77 with a free GoodRx discount.
Frequently asked questions
Not normally. Drowsiness isn’t a typical guaifenesin side effect. But fatigue and sleepiness are common symptoms of infections you may be taking guaifenesin to help manage. Listen to your body and get as much rest as you can. This is one of several self-care tips that can help you recover from your illness.
Research is limited, but guaifenesin is typically considered safe to take after the first trimester (12 weeks) of pregnancy. But everyone’s risks are different and can vary between pregnancies. Always ask your prenatal care team before taking any medications while pregnant.
Mucinex usually starts working within 30 minutes of taking it. But it may take 1 to 2 hours to feel its full effects.
Stand-alone Mucinex likely causes similar side effects for both younger and older adults. But combination products, such as Mucinex DM, may cause more side effects if you’re 65 or older. This is due to the dextromethorphan component. This cough suppressant may cause more severe dizziness or drowsiness for older adults, which can raise the risk of falls. Discuss the safest cold medication for you with your healthcare team.
Not normally. Drowsiness isn’t a typical guaifenesin side effect. But fatigue and sleepiness are common symptoms of infections you may be taking guaifenesin to help manage. Listen to your body and get as much rest as you can. This is one of several self-care tips that can help you recover from your illness.
Research is limited, but guaifenesin is typically considered safe to take after the first trimester (12 weeks) of pregnancy. But everyone’s risks are different and can vary between pregnancies. Always ask your prenatal care team before taking any medications while pregnant.
Mucinex usually starts working within 30 minutes of taking it. But it may take 1 to 2 hours to feel its full effects.
Stand-alone Mucinex likely causes similar side effects for both younger and older adults. But combination products, such as Mucinex DM, may cause more side effects if you’re 65 or older. This is due to the dextromethorphan component. This cough suppressant may cause more severe dizziness or drowsiness for older adults, which can raise the risk of falls. Discuss the safest cold medication for you with your healthcare team.
The bottom line
Guaifenesin (Mucinex) is an over-the-counter medication that can help relieve chest congestion. A common adult guaifenesin dosage is 200 mg to 400 mg every 4 hours as needed. But each product may have different directions. Adults shouldn’t take more than 6 doses of immediate-release guaifenesin per day. Guaifenesin extended-release tablets, including Mucinex maximum strength, should be limited to 2,400 mg per day. For children, the dosage depends on their age.
No special guaifenesin dosage adjustments are typically needed for health conditions. Always check the medication label or ask a healthcare professional for dosing instructions, especially if you’re giving guaifenesin to a child.
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References
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American Diabetes Association. (n.d.). Planning for sick days.
Dr. Reddy’s Laboratories. (2024). Guaifenesin 600 MG- guaifenesin tablet, extended release; Guaifenesin 1200 MG- guaifenesin tablet, extended release [package insert].
Kesin Pharma Corporation. (2025). Guaifenesin liquid [package insert].
Geri-Care Pharmaceuticals. (2025). Geri-tussin- guaifenesin liquid [package insert].
Marlex Pharmaceuticals. (2024). Guaifenesin 200MG- guaifenesin tablet [package insert].
Marlex Pharmaceuticals. (2024). Guaifenesin 400mg- guaifenesin tablet [package insert].
Mucinex. (n.d.). Kids cold & flu symptom relief. RB Health (US).
Prescribers’ Digital Reference. (n.d.). Mucinex.
