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, Antitussin, Chest Congestion Relief, Children's Mucinex, Cough, Diabetic Siltussin DAS-Na, Diabetic Tussin, Good Neighbor Pharmacy Children's Mucus Relief, Good Neighbor Pharmacy Mucus ER, Good Neighbor Pharmacy Mucus Relief, Good Neighbor Pharmacy Tussin, Good Neighbor Pharmacy Tussin Chest Congestion, Good Sense Children's Mucus Relief, Good Sense Tussin, GoodSense Tussin Mucus + Chest Congestion

When This Medicine Should Not Be Used

How to Use This Medicine

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

  • Take your medicine as 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  • Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any outdated medicine or medicine no longer needed.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 7/4/2015

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