What is Guaifenesin ER: Uses, Warnings & Interactions

Updated May 14, 2025  •  Published Dec 30, 2020

Guaifenesin ER overview

BRAND NAMES:

  • Allfen, Chest Congestion Relief, Children's Mucus Relief, Diabetic Siltussin DAS-Na, Diabetic Tussin, Equaline 12HR Mucus-ER, Equate Mucus ER, Geri-Tussin, Good Neighbor Pharmacy Children's Mucus Relief, Good Neighbor Pharmacy Mucus ER, Good Neighbor Pharmacy Mucus Relief, Good Neighbor Pharmacy Tab Tussin, Good Neighbor Pharmacy Tussin, Good Neighbor Pharmacy Tussin Chest Congestion, Good Sense Mucus Relief

Generic Names:

  • Guaifenesin Er

Uses:

  • Thins mucus so you can clear it from your head, throat, and lungs.

Therapeutic Classes:

  • Expectorant

Forms:

  • Capsule, Tablet, Long Acting Capsule, Long Acting Tablet, Liquid

How it’s taken:

  • By mouth

What is Guaifenesin ER used for?

Guaifenesin ER is an expectorant that works by breaking down mucus in the airways, clearing congestion, and making breathing easier. It is used for the temporary relief of coughs caused by the common cold, bronchitis, and other breathing illnesses.

What form(s) does Guaifenesin ER come in

  • Capsule

  • Tablet

  • Long Acting Capsule

  • Long Acting Tablet

  • Liquid

What are common Guaifenesin ER doses?

  • Bottle 14 Tablets Extended Release 12 Hour

Common Guaifenesin ER prescriptions

  • guaiFENesin ER
    100 tablets extended release 12 hour bottle

  • guaiFENesin ER
    20 tablets extended release 12 hour bottle

  • guaiFENesin ER
    40 tablets extended release 12 hour bottle

  • guaiFENesin ER
    14 tablets extended release 12 hour box

How to take Guaifenesin ER

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

  • Follow the instructions on the medicine label if you are using this medicine without a prescription.

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

  • Do not break, chew, or crush the tablet or capsule. Swallow it whole with a full glass of water.

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

  • Do not break, chew, or crush the tablet or capsule. Swallow it whole with a full glass of water.

  • Follow the instructions on the medicine label if you are using this medicine without a prescription.

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

What to do if you miss a dose of Guaifenesin ER

  • You must use this medicine on a fixed schedule. Call your doctor or pharmacist if you miss a dose.

  • Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any outdated medicine or medicine no longer needed.

  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

Guaifenesin ER contraindications

  • You should not use this medicine if you have ever had an allergic reaction to guaifenesin. Do not give any over-the-counter (OTC) cough and cold medicine to a baby or child under 4 years old. Using these medicines in very young children might cause serious or possibly life-threatening side effects.

Guaifenesin ER warnings

  • This medicine may contain alcohol.

  • If you are pregnant or breast feeding, ask your doctor or pharmacist before using this medicine.

  • If your cough is caused by asthma, emphysema, bronchitis, or smoking, talk to your doctor before using this medicine.

Guaifenesin ER interactions

  • If you are pregnant or breast feeding, ask your doctor or pharmacist before using this medicine.

  • If your cough is caused by asthma, emphysema, bronchitis, or smoking, talk to your doctor before using this medicine.

  • This medicine may contain alcohol.

Guaifenesin ER side effects

Serious Side Effects

  • Cough that lasts longer than 7 days.

  • Cough with fever, skin rash, or ongoing headache.

Less Serious Side Effects

  • Drowsiness.

  • Nausea, vomiting, diarrhea, stomach pain.

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