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Promethazine

Generic: Promethazine Hydrochloride

Rx only
Antihistamine✓ FDA-verified
View full FDA label ↗
Promethazine is a medication used to treat allergies, nausea, vomiting, and to help with sedation before and after surgery. It works by blocking certain signals in the brain that can cause these symptoms, making you feel more comfortable. It is taken as a rectal suppository, with a typical starting dose of 25 mg for adults, which can be repeated as needed, but should not exceed 50 mg. A key warning is that it should not be used in children under 2 years old due to the risk of serious breathing problems. Additionally, it should be used with caution if you are taking other medications that can also cause drowsiness, like alcohol or sedatives.
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Uses

  • Perennial and seasonal allergic rhinitis.
  • Vasomotor rhinitis.
  • Allergic conjunctivitis from allergens and foods.
  • Mild allergic skin reactions like hives.
  • Allergic reactions to blood or plasma.
  • Dermographism.
  • Anaphylactic reactions as additional therapy.
  • Sedation before and after surgery.
  • Preventing nausea and vomiting from anesthesia.
  • Motion sickness treatment and prevention.
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Dosage

  • 25 mg before bedtime for allergies. 12.5 mg before meals if needed. 25 mg twice daily for motion sickness. 25 mg for nausea and vomiting every 4 to 6 hours as needed. 12.5 to 25 mg for sedation in children at bedtime. 50 mg for adult sedation before surgery.
  • Always follow your doctor's specific instructions for your dose.
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Side effects

Common

Drowsinesssedationblurred visionDizzinessconfusiondisorientationDry mouthnauseavomitingIncreased or decreased blood pressureRespiratory depression

Serious

which can be fatalSevere allergic reactions like angioedema
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Warnings

⚠ Important warnings

  • Not for children under 2 years due to risk of fatal respiratory depression.
  • Use caution in children 2 years and older.
  • May impair ability to drive or operate machinery.
  • Can cause respiratory depression in patients with breathing issues.
  • May lower seizure threshold in patients with seizure disorders.
  • Avoid using with other CNS depressants like alcohol.
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Drug interactions

  • Alcoholincreases sedation effectsMonitor
  • Narcoticsmay require dose reductionCaution
  • Barbituratesreduce dose by halfCaution
  • Epinephrinemay reverse its effectsCaution
  • Anticholinergicsuse with cautionCaution
  • Monoamine Oxidase Inhibitorsincreased risk of side effectsMonitor

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Medical Disclaimer: This content is provided for informational and educational purposes only and is not intended as medical advice. Always consult a qualified healthcare provider before taking any medication.
Data Source: Publicly available drug labeling information from the U.S. Food and Drug Administration (FDA).