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Doxylamine and phenylephrine

Generic Name: doxylamine and phenylephrine (dox IL a meen and FEN il EFF rin)
Brand Name: Poly Hist Forte

Medically reviewed by Drugs.com on Jun 28, 2019 – Written by Cerner Multum

What is doxylamine and phenylephrine?

Doxylamine is an antihistamine that reduces the effects of natural chemical histamine in the body. Histamine can produce symptoms of sneezing, itching, watery eyes, and runny nose.

Phenylephrine is a decongestant that shrinks blood vessels in the nasal passages. Dilated blood vessels can cause nasal congestion (stuffy nose).

Doxylamine and phenylephrine is a combination medicine used to treat runny or stuffy nose, sneezing, itching, watery eyes, and sinus congestion caused by allergies, the common cold, or the flu.

Doxylamine and phenylephrine may also be used for purposes not listed in this medication guide.

Important Information

Do not use doxylamine and phenylephrine if you have used an MAO inhibitor in the past 14 days, such as isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, or tranylcypromine.

Do not use this medicine only to make a child sleepy.

Before taking this medicine

You should not use this medicine if you are allergic to doxylamine or phenylephrine.

Do not use doxylamine and phenylephrine if you have used an MAO inhibitor in the past 14 days. A dangerous drug interaction could occur. MAO inhibitors include isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, tranylcypromine, and others.

Ask a doctor or pharmacist if this medicine is safe to use if you have:

Ask a doctor before using this medicine if you are pregnant or breastfeeding.

How should I take doxylamine and phenylephrine?

Use exactly as directed on the label, or as prescribed by your doctor. Cold or cough medicine is only for short-term use until your symptoms clear up.

Swallow the tablet whole and do not crush, chew, or break it.

Always follow directions on the medicine label about giving cough or cold medicine to a child. Do not use the medicine only to make a child sleepy. Death can occur from the misuse of cough or cold medicines in very young children.

Call your doctor if your symptoms do not improve after 7 days of treatment, or if you have a fever with a headache, cough, or skin rash.

If you need surgery or medical tests, tell the surgeon or doctor ahead of time if you have taken doxylamine and phenylephrine within the past few days.

Store at room temperature away from moisture and heat.

What happens if I miss a dose?

Since doxylamine and phenylephrine is used when needed, you may not be on a dosing schedule. Skip any missed dose if it's almost time for your next dose. Do not use two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking doxylamine and phenylephrine?

Avoid driving or hazardous activity until you know how doxylamine and phenylephrine will affect you. Your reactions could be impaired.

Ask a doctor or pharmacist before using other cough or cold medicines that may contain similar ingredients.

Drinking alcohol can increase certain side effects of doxylamine.

Doxylamine and phenylephrine side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Stop using this medicine and call your doctor at once if you have:

  • severe dizziness;

  • nervousness, trouble sleeping;

  • little or no urination; or

  • high blood pressure (severe headache, pounding in your neck or ears).

Common side effects may include:

  • dizziness, drowsiness;

  • dry mouth, nose, or throat;

  • constipation;

  • blurred vision; or

  • feeling restless or excited (especially in children).

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect doxylamine and phenylephrine?

Avoid using doxylamine and phenylephrine with other drugs that cause drowsiness or slow your breathing (such as opioid medicine, a muscle relaxer, or medicine for anxiety or seizures). Ask a doctor or pharmacist before using any other medication, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed in this medication guide.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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