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Promethazine DM

Generic name: dextromethorphan and promethazinedex-troe-me-THOR-fan-and-pro-METH-a-zeen ]
Drug class: Upper respiratory combinations

Medically reviewed by on Aug 11, 2023. Written by Cerner Multum.

What is Promethazine DM?

Dextromethorphan is a cough suppressant. Promethazine is an antihistamine.

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

Promethazine DM is for use in adults and children at least 2 years old.

Promethazine DM may also be used for purposes not listed in this medication guide.

Promethazine DM 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.

This medicine may cause serious side effects. 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 of Promethazine DM 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.


Promethazine can slow the breathing, which has caused death in very young children. Do not use Promethazine DM in a child younger than 2 years old. Follow all directions when giving the medicine to a child 2 years or older.

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

Before taking this medicine

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

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:

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.

How should I take Promethazine DM?

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

Do not use Promethazine DM 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 Promethazine DM 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 happens if I miss a dose?

Promethazine DM is used when needed. If you are on a dosing schedule, skip any missed 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.

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

What should I avoid while taking Promethazine DM?

Avoid driving, riding a bike, or any other hazardous activity until you know how Promethazine DM 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.

What other drugs will affect Promethazine DM?

Using Promethazine DM with other drugs that make you drowsy can worsen this effect. Ask your doctor before using opioid medication, a sleeping pill, a muscle relaxer, or medicine for anxiety or seizures.

Tell your doctor about all your other medicines, especially:

This list is not complete. Other drugs may affect Promethazine DM, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug 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.