Promethazine DM (Dextromethorphan And Promethazine) – Side Effects, Interactions, Uses, Dosage, Warnings

Dextromethorphan is a cough suppressant. Promethazine is an antihistamine.

Dextromethorphan and promethazine is a combination medicine used to treat cough, stuffy nose, runny nose, and sneezing caused by colds or allergies.

This medicine is for use in adults and children at least 2 years old.

Dextromethorphan and promethazine may also be used for purposes not listed in this medication guide.


What is Promethazine DM (Dextromethorphan And Promethazine) used for?

  • Allergic Rhinitis
  • Cold Symptoms
  • Cough


What is the most important information I should know about Promethazine DM (Dextromethorphan And Promethazine)?

You should not use this medicine if you are allergic to dextromethorphan or promethazine, or if you have:

  • asthma or other breathing problems; or
  • an allergy to medicines similar to promethazine (chlorpromazine, fluphenazine, prochlorperazine, thioridazine, and others).

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, tranylcypromine, and others.

Tell your doctor if you have ever had:

  • chronic obstructive pulmonary disease (COPD), sleep apnea, or other breathing disorder;
  • a seizure;
  • eczema;
  • bone marrow depression;
  • glaucoma;
  • a stomach ulcer;
  • blockage in your stomach or intestines;
  • a bladder obstruction or other urination problems;
  • an enlarged prostate;
  • liver disease;
  • heart problems; or
  • if you are on bed rest or otherwise debilitated.

Tell your doctor if you are pregnant or breastfeeding.

Taking this medicine during the last 2 weeks of pregnancy may increase the risk of bleeding in the newborn baby.

Ask a doctor before giving this medicine to a child younger than 12 years old.

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Side Effects

What are the side effects of Promethazine DM (Dextromethorphan And Promethazine)?

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:

  • weak or shallow breathing, breathing that stops during sleep;
  • unusual restlessness or excitement;
  • uncontrolled muscle movements in your neck, tongue, or eyes;
  • fast, slow, or uneven heart rate;
  • hallucinations, ringing in your ears;
  • a seizure;
  • fever, chills, weakness;
  • easy bruising, unusual bleeding;
  • yellowing of your skin or eyes; or
  • severe nervous system reaction–very stiff (rigid) muscles, high fever, sweating, confusion, fast or uneven heartbeats, tremors, feeling like you might pass out.

Common side effects may include:

  • drowsiness, dizziness;
  • dry mouth, nose, or throat;
  • blurred vision;
  • nausea, vomiting; or
  • loss of coordination.

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.

Pregnancy & Breastfeeding

Can I take Promethazine DM (Dextromethorphan And Promethazine) if I’m pregnant or breastfeeding?

Risk cannot be ruled out
Based on FDA pregnancy categories

Tell your doctor if you are pregnant or breastfeeding.


What drugs and food should I avoid while taking Promethazine DM (Dextromethorphan And Promethazine)?

Avoid driving, riding a bike, or any other hazardous activity until you know how this medicine will affect you. Your reactions could be impaired.

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

Avoid drinking alcohol.

Avoid sunlight, and wear protective clothing and use sunscreen (SPF 30 or higher) when you are outdoors.

Dosage Guidelines & Tips

How to take Promethazine DM (Dextromethorphan And Promethazine)?

Use Promethazine DM (Dextromethorphan And Promethazine) exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Do not use this medicine in a child younger than 2 years old, and carefully follow all dosing directions about use in a child 2 years or older. Promethazine can slow the breathing, which has caused death in very young children.

Measure liquid medicine with the supplied syringe or a dose-measuring device (not a kitchen spoon).

This medicine can affect the results of certain medical tests, and may cause false results on a pregnancy test. Tell the doctor or laboratory staff if you have taken dextromethorphan and promethazine in the past few days.

Call your doctor if your symptoms do not improve, or if they get worse.

Store at room temperature away from moisture and heat. Keep the bottle tightly closed when not in use.

What should I do if I missed a dose of Promethazine DM (Dextromethorphan And Promethazine)?

Dextromethorphan and promethazine is used when needed. If you are on a dosing schedule, skip any missed dose. Do not use two doses at one time.

Overdose Signs

What happens if I overdose on Promethazine DM (Dextromethorphan And Promethazine)?

Overdose symptoms may include overactive reflexes, feeling restless or confused, slow breathing, dilated pupils, or fainting.

If you think you or someone else may have overdosed on: Promethazine DM (Dextromethorphan And Promethazine),  call your doctor or the Poison Control center

(800) 222-1222

If someone collapses or isn't breathing after taking Promethazine DM (Dextromethorphan And Promethazine), call 911


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