Guaifenesin, Dextromethorphan, and Phenylephrine









Guaifenesin, Dextromethorphan, and Phenylephrine


Pharmacologic Category
Antitussive/Decongestant
Reasons not to take this medicine
  • If you have an allergy to guaifenesin, dextromethorphan, phenylephrine or any other part of this medicine.
  • Tell healthcare provider if you are allergic to any medicine. Make sure to tell about the allergy and how it affected you. This includes telling about rash; hives; itching; shortness of breath; wheezing; cough; swelling of face, lips, tongue, or throat; or any other symptoms involved.
  • If you have any of the following conditions: Heart disease or high blood pressure.
  • If you have prostatic hypertrophy.
  • If you have taken isocarboxazid, phenelzine, or tranylcypromine in the last 14 days. Monoamine oxidase inhibitors (eg, isocarboxazid, phenelzine, and tranylcypromine) must be stopped 14 days before this medicine is started. Taking the two together could cause dangerously high blood pressure.
  • If you are breast-feeding.
What is this medicine used for?
  • This medicine is used to thin secretions.
  • This medicine is used to relieve nasal congestion.
  • This medicine is used to stop coughing.
How does it work?
  • Guaifenesin thins fluids in the lungs.
  • Phenylephrine shrinks swollen nasal tissue and opens up passages.
  • Dextromethorphan affects the cough center in the brain.
How is it best taken?
  • Take this medicine with a full glass of water.
  • Take this medicine with or without food. Take with food if it causes an upset stomach.
  • Drink plenty of noncaffeine-containing liquid unless told to drink less liquid by healthcare provider.
  • Long-acting tablets may be broken in half for dosing purposes.
  • Long-acting products: Swallow whole. Do not chew, break, or crush.
  • A liquid (syrup) is available if you cannot swallow pills.
  • Those who have feeding tubes can also use the liquid. Flush the feeding tube before and after medicine is given.
What do I do if I miss a dose? (does not apply to patients in the hospital)
  • Take a missed dose as soon as possible.
  • If it is almost time for the next dose, skip the missed dose and return to your regular schedule.
  • Do not take a double dose or extra doses.
  • Many times this medicine is taken on an as needed basis.
What are the precautions when taking this medicine?
  • Check medicines with healthcare provider. This medicine may not mix well with other medicines.
  • If you have PKU, talk with healthcare provider. Some products do contain phenylalanine.
  • If you have high blood pressure, talk with healthcare provider.
  • If you have diabetes mellitus, talk with healthcare provider.
  • If you have thyroid disease, talk with healthcare provider.
  • If you have glaucoma, talk with healthcare provider.
  • Tell healthcare provider if you are pregnant or plan on getting pregnant.
  • Tell healthcare provider if you are breast-feeding.
What are some possible side effects of this medicine?
  • Feeling nervous and excitable.
  • Dry mouth. Frequent mouth care, sucking hard, sugar-free candy, or chewing sugar-free gum may help.
  • Inability to sleep.
  • Feeling dizzy. Rise slowly over several minutes from sitting or lying position. Be careful climbing.
  • Headache.
  • Nausea or vomiting. Small frequent meals, frequent mouth care, sucking hard, sugar-free candy, or chewing sugar-free gum may help.
What should I monitor?
  • Change in condition being treated. Is it better, worse, or about the same?
  • Take good care of your teeth. See a dentist regularly.
Reasons to call healthcare provider immediately
  • If you suspect an overdose, call your local poison control center immediately or dial 911.
  • Signs of a life-threatening reaction. These include wheezing; chest tightness; fever; itching; bad cough; blue skin color; fits; or swelling of face, lips, tongue, or throat.
  • Persistent cough.
  • Chest pain or pressure or fast heartbeat.
  • Severe dizziness or passing out.
  • Difficulty breathing.
  • Feeling extremely tired or weak.
  • Severe headache.
  • Any rash.
  • No improvement in condition or feeling worse.
How should I store this medicine?
  • Store at room temperature.
  • Protect from light.
  • Protect from moisture. Do not store in a bathroom or kitchen.
General statements
  • If you have a life-threatening allergy, wear allergy identification at all times.
  • Do not share your medicine with others and do not take anyone else's medicine.
  • Keep all medicine out of the reach of children and pets.
  • Keep a list of all your medicines (prescription, natural products, supplements, vitamins, over-the-counter) with you. Give this list to healthcare provider (doctor, nurse, nurse practitioner, pharmacist, physician assistant).
  • Talk with healthcare provider before starting any new medicine, including over-the-counter, natural products, or vitamins.
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