Medically Reviewed on 11/10/2022

Generic Name: brompheniramine/dextromethorphan/phenylephrine

Brand Names: Neo DM Suspension, Dimaphen DM, Children's Dimetapp Cold and Cough

Drug Class: Cough/Cold, Non-narcotic Combos; Antihistamine/Antitussive/Decongestant Combos

What is brompheniramine/dextromethorphan/phenylephrine, and what is it used for?

Brompheniramine/dextromethorphan/phenylephrine is a combination drug used to relieve symptoms of the common cold, flu, hay fever, allergies, and respiratory conditions such as sinusitis and bronchitis. The combo medication temporarily relieves symptoms such as cough, runny nose, nasal congestion, sneezing, itchy nose or throat, and itchy/watery eyes due to minor throat and bronchial irritation, and makes breathing easier. The drug is available over the counter (OTC) in the U.S.

Each medication in the combination works in a different way, and when combined they are more effective in relieving symptoms than with monotherapy of just one of the drugs.

  • Brompheniramine works by blocking the activity of histamine, a natural compound in the body that causes allergy symptoms. Histamine is released by mast cells and basophils, types of immune cells, in response to allergen exposure. Brompheniramine binds to histamine H1 receptors in blood vessels, respiratory tract, and gastrointestinal tract, preventing their activation by histamine and the resultant allergic reaction.
  • Dextromethorphan suppresses cough by reducing the sensitivity of cough receptors in the brain region that stimulate the cough reflex and prevent the transmission of cough impulses. Dextromethorphan is a non-opioid drug derived from levorphanol, an opioid painkiller (analgesic), and is structurally similar to opioid drugs such as codeine, however, it does not have analgesic or addictive properties.
  • Phenylephrine is an alpha1 agonist that works by stimulating the activity of alpha1 adrenergic receptors, protein molecules that signal to the smooth muscles around blood vessels to contract. The smooth muscle contraction narrows the blood vessels, limiting blood flow to the swollen respiratory mucous tissue, reducing nasal and bronchial congestion, and making breathing easier.



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What are the side effects of brompheniramine/dextromethorphan/phenylephrine?

Common side effects of brompheniramine/dextromethorphan/phenylephrine include:

Call your doctor immediately if you experience any of the following symptoms or serious side effects while using this drug:

  • Serious heart symptoms include fast or pounding heartbeats, fluttering in your chest, shortness of breath, and sudden dizziness;
  • Severe headache, confusion, slurred speech, severe weakness, vomiting, loss of coordination, feeling unsteady;
  • Severe nervous system reaction with very stiff muscles, high fever, sweating, confusion, fast or uneven heartbeats, tremors, and feeling like you might pass out; or
  • Serious eye symptoms include blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights.

This is not a complete list of all side effects or adverse reactions that may occur from the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may also report side effects or health problems to the FDA at 1-800-FDA-1088.

What are the dosages of brompheniramine/dextromethorphan/phenylephrine?

Oral Solution

  • 1 mg/5 mg/2.5 mg/5 mL

Relief of Cold Symptoms


4 teaspoons (20 mL) orally every 4 hours; not to exceed 120 mL/24 hours


Children below 6 years

  • Not recommended

Children 6-12 years

  • 2 teaspoons (10 mL) orally every 4 hours

Children above 12 years

  • 4 teaspoons (20 mL) orally every 4 hours


  • Brompheniramine/dextromethorphan/phenylephrine overdose can cause severe adverse reactions with symptoms that include agitation, confusion, flushing, hallucinations, large pupils, muscle twitching, and seizures.
  • In children, the drug may initially have an excitatory effect, which may be followed by loss of coordination, drowsiness, loss of consciousness and seizures.
  • Overdose treatment may be supportive and symptomatic care.

What drugs interact with brompheniramine/dextromethorphan/phenylephrine?

Inform your doctor of all medications you are currently taking, who can advise you on any possible drug interactions. Never begin taking, suddenly discontinue, or change the dosage of any medication without your doctor’s recommendation.

  • Severe interactions of brompheniramine/dextromethorphan/phenylephrine include:
    • iobenguane I 123
    • isocarboxazid
    • linezolid
    • phenelzine
    • phenelzine
    • procarbazine
    • rasagiline
    • selegiline transdermal
    • safinamide
    • selegiline
    • tranylcypromine
  • Brompheniramine/dextromethorphan/phenylephrine has serious interactions with at least 58 different drugs.
  • Brompheniramine/dextromethorphan/phenylephrine has moderate interactions with at least 303 different drugs.
  • Brompheniramine/dextromethorphan/phenylephrine has mild interactions with at least 36 different drugs.

The drug interactions listed above are not all of the possible interactions or adverse effects. For more information on drug interactions, visit the RxList Drug Interaction Checker.

It is important to always tell your doctor, pharmacist, or health care provider about all prescription and over-the-counter medications you use, as well as the dosage for each, and keep a list of the information. Check with your doctor or healthcare provider if you have any questions about the medication.

Pregnancy and breastfeeding

  • Neither animal reproductive studies nor controlled studies in pregnant women have been conducted on the safety of brompheniramine/dextromethorphan/phenylephrine use during pregnancy. It is not known if the combination drug can cause fetal harm or affect reproductive capacity. Use with caution in pregnant women only if maternal benefits clearly outweigh possible risk to the fetus.
  • The combination drug contains brompheniramine, an antihistamine. There is a higher risk of antihistamine intolerance in small infants, avoid use in nursing mothers.
  • If you are pregnant or breastfeeding, consult your healthcare provider before taking any OTC drug.

What else should I know about brompheniramine/dextromethorphan/phenylephrine?

  • Take brompheniramine/dextromethorphan/phenylephrine exactly as prescribed, or as per label instructions if taking OTC drug. Do not take higher or more frequent doses than recommended.
  • Stop taking the medication and see your physician if:
    • Your symptoms include fever, rash, or persistent headache or do not get better within 7 days
    • Cough persists for more than 1 week, tends to recur, or is accompanied by fever, rash, or persistent headache,
    • You develop sleeplessness, nervousness, or dizziness
  • The antihistamine component in the drug may impair physical and mental abilities; avoid activities such as driving and operating heavy machinery.
  • Tell your doctor ahead of time if you have taken this drug within the previous a few days, if surgery or medical tests need to be performed.
  • This combo medication can reduce sweating. Avoid becoming overheated or dehydrated during exercise and hot weather, it may increase the risk of heat stroke.
  • Avoid drinking alcohol while taking brompheniramine/dextromethorphan/phenylephrine.
  • Do not administer OTC brompheniramine/dextromethorphan/phenylephrine to children younger than 2 years.
  • Store safely out of reach of children.
  • In case of overdose, seek medical help or call Poison Control.

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Brompheniramine/dextromethorphan/phenylephrine is an over-the-counter (OTC) cold medication used to relieve symptoms of the common cold, flu, hay fever, allergies, and respiratory conditions such as sinusitis and bronchitis. The combo medication temporarily relieves symptoms such as cough, runny nose, nasal congestion, sneezing, itchy nose or throat, and itchy/watery eyes due to minor throat and bronchial irritation, and makes breathing easier. Do not use concurrently with other sedative drugs or alcohol. Common side effects of brompheniramine/dextromethorphan/phenylephrine include dry mouth, nose, and throat; thickening of mucus in nose and throat, drowsiness, dizziness, headache, excitability, restlessness, high blood pressure (hypertension), reflex increase in heart rate (tachycardia), and constriction of peripheral and abdominal (visceral) blood vessels.

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You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

Medically Reviewed on 11/10/2022