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Diphenhydramine and phenylephrine

Generic Name: diphenhydramine and phenylephrine (DYE fen HYE dra meen and FEN il EFF rin)
Brand Name: Children's Triacting Night Time, Dimetapp Nighttime Cold & Congestion, Dytan-D, Triaminic Night Time Cold & Cough, ...show all 21 brand names
Dosage Forms: oral liquid (12.5 mg-5 mg/5 mL; 6.25 mg-2.5 mg/5 mL); oral suspension, extended release (25 mg-7.5 mg/5 mL); oral tablet, chewable, extended release (25 mg-10 mg)

Medically reviewed by Drugs.com on Sep 29, 2020 – Written by Cerner Multum

What is diphenhydramine and phenylephrine?

Diphenhydramine is an antihistamine. Phenylephrine is a decongestant.

Diphenhydramine 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.

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

Important Information

Do not use diphenhydramine 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.

Use this medicine exactly as directed. Taking too much diphenhydramine can lead to serious heart problems, seizures, coma, or death.

Do not use this medicine to make a child sleepy. Ask a doctor before giving the medicine to a child younger than 6 years old.

Ask a doctor or pharmacist before using any other medicine that may contain diphenhydramine. Taking too much of this medicine can lead to a fatal overdose.

Before taking this medicine

Do not use this medicine 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 ever had:

This medicine may contain phenylalanine. Check the medication label if you have phenylketonuria (PKU).

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

How should I take diphenhydramine 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.

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.

Ask a doctor before giving the medicine to a child younger than 6 years old.

You must chew the chewable tablet before you swallow it.

Measure liquid medicine carefully. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon).

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 doctor ahead of time if you have taken a cold medicine within the past few days.

Store at room temperature away from moisture and heat.

What happens if I miss a dose?

Since diphenhydramine 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. An overdose of diphenhydramine and phenylephrine can be fatal.

Overdose symptoms may include vomiting, confusion, severe drowsiness, ringing in your ears, no urination, very dry eyes and mouth, dilated pupils, fast heartbeats, tremor, agitation, hallucinations, or seizure.

What should I avoid while taking diphenhydramine and phenylephrine?

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

Ask a doctor or pharmacist before using any other medicine that may contain diphenhydramine. This includes medicines for sleep, cold/allergy symptoms, or anti-itch medicine used on the skin. Using too much diphenhydramine may lead to a fatal overdose.

Drinking alcohol with this medicine can cause side effects.

Diphenhydramine 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 drowsiness;

  • painful or difficult urination;

  • fast, pounding, or uneven heartbeats;

  • trouble breathing;

  • anxiety, nervousness;

  • a seizure; or

  • problems with balance or speech.

Common side effects may include:

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.

Diphenhydramine and phenylephrine dosing information

Usual Adult Dose for Allergic Rhinitis:

Diphenhydramine 12.5 mg / phenylephrine 5 mg per 10 mL liquid: 20 mL every 4 hours
Maximum dose: 6 doses per 24 hours

Diphenhydramine 25 mg / phenylephrine 10 mg per tablet: 1 tablet every 4 hours
Maximum dose: 6 doses per 24 hours

Usual Adult Dose for Cold Symptoms:

Diphenhydramine 12.5 mg / phenylephrine 5 mg per 10 mL liquid: 20 mL every 4 hours
Maximum dose: 6 doses per 24 hours

Diphenhydramine 25 mg / phenylephrine 10 mg per tablet: 1 tablet every 4 hours
Maximum dose: 6 doses per 24 hours

Usual Pediatric Dose for Allergic Rhinitis:

Diphenhydramine 6.25 mg / phenylephrine 2.5 mg per 5 mL liquid:
6 to under 12 years: 10 mL every 4 hours
Maximum dose: 6 doses per 24 hours

Diphenhydramine 12.5 mg / phenylephrine 5 mg per 10 mL liquid:
12 years and older: 20 mL every 4 hours
6 to under 12 years: 10 mL every 4 hours
Maximum dose: 6 doses per 24 hours

Diphenhydramine 25 mg / phenylephrine 10 mg per tablet:
12 years and older: 1 tablet every 4 hours
Maximum dose: 6 doses per 24 hours

Usual Pediatric Dose for Cold Symptoms:

Diphenhydramine 6.25 mg / phenylephrine 2.5 mg per 5 mL liquid:
6 to under 12 years: 10 mL every 4 hours
Maximum dose: 6 doses per 24 hours

Diphenhydramine 12.5 mg / phenylephrine 5 mg per 10 mL liquid:
12 years and older: 20 mL every 4 hours
6 to under 12 years: 10 mL every 4 hours
Maximum dose: 6 doses per 24 hours

Diphenhydramine 25 mg / phenylephrine 10 mg per tablet:
12 years and older: 1 tablet every 4 hours
Maximum dose: 6 doses per 24 hours

What other drugs will affect diphenhydramine and phenylephrine?

Ask a doctor or pharmacist before using diphenhydramine and phenylephrine with any other medicines, especially drugs that can cause drowsiness (such as opioid medication, sleep medicine, a muscle relaxer, or medicine for anxiety or seizures). Tell your doctor about all your current medicines and any medicine you start or stop using. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here.

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.