Guaifenesin (By mouth)


Guaifenesin (gwye-FEN-e-sin)

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

Brand Name(s)

Allfen, Chest Congestion Relief, Children's Mucinex, Children's Mucus Relief, Cough, Diabetic Siltussin DAS-Na, Diabetic Tussin, 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

When This Medicine Should Not Be Used

How to Use This Medicine

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

  • 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.

If a dose is missed:

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

How to Store and Dispose of This Medicine

  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Do not freeze the oral liquid.
  • Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any outdated medicine or medicine no longer needed.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.

Drugs and Foods to Avoid

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

Warnings While Using This Medicine

  • 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.

Possible Side Effects While Using This Medicine

Call your doctor right away if you notice any of these side effects:

  • Cough that lasts longer than 7 days.
  • Cough with fever, skin rash, or ongoing headache.

If you notice these less serious side effects, talk with your doctor:

  • Drowsiness.
  • Nausea, vomiting, diarrhea, stomach pain.

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Version Info

  • Last reviewed on 10/4/2017

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission ( URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- 2013 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.