Yellow “Promethazine DM” is a combination drug that contains two active ingredients:
| Ingredient | Typical Dose per Tablet | Main Action |
|------------|------------------------|-------------|
| Promethazine (H1‑antihistamine) | 5 mg | Reduces histamine‑mediated allergy symptoms, causes sedation, and has anti‑emetic properties. |
| Dextromethorphan (Cough suppressant) | 10 mg | Blocks cough‑reflex in the brain. |
The tablets are usually yellow or green‑yellow in color and are sold under brand names such as Promethazine DM, Dextromethorphan + Promethazine, etc. The “DM” in the name stands for “Dextromethorphan” rather than a dosage strength.
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Why is it used?
1. Cough – especially dry, non‑productive coughs.
2. Allergic rhinitis – nasal itching, sneezing, runny nose.
3. Motion sickness & nausea – the promethazine component helps prevent vomiting.
4. Sedation – often prescribed for patients who need help sleeping or to ease anxiety (though this is less common in some countries).
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Typical dosing (adult)
- Standard dose: 5 mg promethazine + 10 mg dextromethorphan per tablet.
- Frequency: 2–3 times a day, not exceeding 30 mg promethazine (i.e., 6 tablets) or 60 mg dextromethorphan (i.e., 12 tablets) in 24 h.
- Maximum daily dose: 30 mg promethazine + 60 mg dextromethorphan (≈ 6 tablets).
Note: Doses for children are usually lower and based on body weight; they must be prescribed by a qualified clinician.
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Common side‑effects
| Symptom | Who is most at risk? |
|---------|----------------------|
| Drowsiness, sedation | All patients, especially when combined with alcohol or other CNS depressants |
| Dry mouth, blurred vision | All |
| Constipation, urinary retention | Older adults, those with prostate issues |
| Low blood pressure (orthostatic hypotension) | Elderly, those on antihypertensives |
| Dizziness, fainting | Elderly, or those taking other sedatives |
| Rarely, agitation or hallucinations | High doses or in susceptible individuals |
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Precautions & Contraindications
- Never use with alcohol, opioids, benzodiazepines, or other sedatives – the risk of respiratory depression and excessive sedation rises sharply.
- Avoid in asthma or severe COPD – both drugs can cause bronchoconstriction.
- Pregnancy & lactation – limited data; usually avoided unless the benefit outweighs the risk.
- Liver or kidney disease – dose adjustments may be necessary.
- Children under 6 y – the drug is usually not recommended; use with extreme caution in older children.
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Drug interactions
| Drug | Interaction | Why it matters |
|------|-------------|----------------|
| MAO inhibitors | Severe serotonin syndrome | Not recommended together |
| SSRIs / SNRIs | Serotonin syndrome | Overlap in serotonergic activity |
| Other antihistamines | Additive sedation | Double‑dose drowsiness |
| Antacids (Aluminum) | Decrease absorption of promethazine | May reduce efficacy |
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When to seek medical help
- Severe or worsening breathing difficulties.
- Uncontrolled drowsiness or confusion.
- Signs of an allergic reaction – rash, swelling, difficulty breathing.
- Unexplained fainting or dizziness.
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Bottom line
Yellow “Promethazine DM” is a common, prescription‑only cough‑suppressant that also treats allergy symptoms and nausea. It works best when taken exactly as prescribed and with caution around other sedating substances. Always read the patient information leaflet and, if you have any doubts about dosage or safety, talk to your pharmacist or prescribing doctor.
If you have a specific question (e.g., exact dosing for your age, how it interacts with a medication you’re already taking, or whether it’s suitable for a child), let me know and I’ll dive deeper!