Guaifenesin/phenylephrine (By mouth)


Guaifenesin (gwye-FEN-e-sin), Phenylephrine (fen-il-EF-rin)

Treats cough and stuffy nose caused by hay fever or the common cold. Also thins mucus to make a cough more productive. This medicine is a combination of an expectorant and a decongestant.

Brand Name(s)

Ambi 10PEH/400GFN, Chest Congestion Relief PE, Children's Mucinex Cold, Children's Triaminic Chest & Nasal Congestion, Crantex, Deconex IR, Despec, ED Bron GP, Entex LQ, GFN 1200/Phenylephrine 40, Gilphex TR, J-Max, Liquibid D-R, Liquibid PD-R, Maxiphen

When This Medicine Should Not Be Used

How to Use This Medicine

Long Acting Tablet, Tablet, Syrup, Liquid, Solution, Capsule, 12 Hour Tablet

  • Take your medicine as directed.
  • Follow the instructions on the medicine label if you are using this medicine without a prescription.
  • Swallow the capsule or tablet whole. Do not crush, break, or chew it.
  • Measure the oral liquid medicine with a marked measuring spoon, oral syringe, or medicine cup.
  • You may take this medicine with food if it upsets your stomach.

If a dose is missed:

  • Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed 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 refrigerate or freeze the liquid form of this medicine.
  • Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any outdated medicine or medicine no longer needed.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.

  • Make sure your doctor knows if you are also using a beta-blocker such as atenolol, labetalol, metoprolol, propranolol, timolol, Inderal®, or Toprol®. Tell your doctor if you are using digoxin (Lanoxin®), guanethidine (Ismelin®), mecamylamine (Inversine), methyldopa (Aldomet®), or reserpine. Your doctor should know if you use medicine for depression such as amitriptyline, doxepin, nortriptyline, Elavil®, Pamelor®, or Sinequan®.

Warnings While Using This Medicine

  • Make sure your doctor knows if you are pregnant or breastfeeding.
  • Tell your doctor if you have diabetes, thyroid problems, high blood pressure, glaucoma, an enlarged prostate, or a history of heart disease.
  • Older adults may be more likely to have side effects from this medicine.
  • Do not give this medicine to a child under 12 years of age, unless your doctor tells you to.
  • Tell any doctor or dentist who treats you that you are using this medicine. This medicine may affect certain medical test results.

Possible Side Effects While Using This Medicine

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

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Fast, pounding, or uneven heartbeat.
  • Feeling extremely confused, fearful, or anxious.
  • High fever, skin rash, sore throat, ongoing headache.
  • Lightheadedness or fainting.
  • No improvement in your symptoms after using the medicine for 7 days.
  • Seizure, hallucinations, vomiting.
  • Shallow breathing, pale skin.
  • Unusual weakness, tremors, or shaking.

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

  • Anxiety, fear, depression, nervousness.
  • Dizziness, trouble sleeping.
  • Feelings of excitement, elevated mood, or increased energy.
  • Loss of appetite.
  • Mild fever or headache.
  • Nausea.

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 8/4/2014

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