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Dextromethorphan / Promethazine Dosage

Medically reviewed on January 16, 2018.

Applies to the following strengths: 15 mg-6.25 mg/5 mL

Usual Adult Dose for Allergic Rhinitis

5 mL orally every 4 to 6 hours
Maximum dose: 30 mL in 24 hours (promethazine 37.5 mg; dextromethorphan 90 mg)

Comments:
-Each 5 mL contains promethazine 6.25 mg and dextromethorphan 15 mg.

Use: For the temporary relief of coughs and upper respiratory symptoms associated with allergy or the common cold.

Usual Adult Dose for Cold Symptoms

5 mL orally every 4 to 6 hours
Maximum dose: 30 mL in 24 hours (promethazine 37.5 mg; dextromethorphan 90 mg)

Comments:
-Each 5 mL contains promethazine 6.25 mg and dextromethorphan 15 mg.

Use: For the temporary relief of coughs and upper respiratory symptoms associated with allergy or the common cold.

Usual Adult Dose for Cough

5 mL orally every 4 to 6 hours
Maximum dose: 30 mL in 24 hours (promethazine 37.5 mg; dextromethorphan 90 mg)

Comments:
-Each 5 mL contains promethazine 6.25 mg and dextromethorphan 15 mg.

Use: For the temporary relief of coughs and upper respiratory symptoms associated with allergy or the common cold.

Usual Pediatric Dose for Allergic Rhinitis

Less than 2 years: Contraindicated

2 years to less than 6 years: 1.25 to 2.5 mL orally every 4 to 6 hours
Maximum dose: 10 mL in 24 hours (promethazine 12.5 mg; dextromethorphan 30 mg)

6 years to less than 12 years: 2.5 to 5 mL orally every 4 to 6 hours
Maximum dose: 20 mL in 24 hours (promethazine 25 mg; dextromethorphan 60 mg)

12 years to 18 years: 5 mL orally every 4 to 6 hours
Maximum dose: 30 mL in 24 hours (promethazine 37.5 mg; dextromethorphan 90 mg)

Comments:
-Each 5 mL contains promethazine 6.25 mg and dextromethorphan 15 mg.
-Extra caution is advised with use of promethazine in children as respiratory depression is strongly associated with use; however, its occurrence is not directly related to individualized weight base dosing.

Use: For the temporary relief of coughs and upper respiratory symptoms associated with allergy or the common cold.

Usual Pediatric Dose for Cold Symptoms

Less than 2 years: Contraindicated

2 years to less than 6 years: 1.25 to 2.5 mL orally every 4 to 6 hours
Maximum dose: 10 mL in 24 hours (promethazine 12.5 mg; dextromethorphan 30 mg)

6 years to less than 12 years: 2.5 to 5 mL orally every 4 to 6 hours
Maximum dose: 20 mL in 24 hours (promethazine 25 mg; dextromethorphan 60 mg)

12 years to 18 years: 5 mL orally every 4 to 6 hours
Maximum dose: 30 mL in 24 hours (promethazine 37.5 mg; dextromethorphan 90 mg)

Comments:
-Each 5 mL contains promethazine 6.25 mg and dextromethorphan 15 mg.
-Extra caution is advised with use of promethazine in children as respiratory depression is strongly associated with use; however, its occurrence is not directly related to individualized weight base dosing.

Use: For the temporary relief of coughs and upper respiratory symptoms associated with allergy or the common cold.

Usual Pediatric Dose for Cough

Less than 2 years: Contraindicated

2 years to less than 6 years: 1.25 to 2.5 mL orally every 4 to 6 hours
Maximum dose: 10 mL in 24 hours (promethazine 12.5 mg; dextromethorphan 30 mg)

6 years to less than 12 years: 2.5 to 5 mL orally every 4 to 6 hours
Maximum dose: 20 mL in 24 hours (promethazine 25 mg; dextromethorphan 60 mg)

12 years to 18 years: 5 mL orally every 4 to 6 hours
Maximum dose: 30 mL in 24 hours (promethazine 37.5 mg; dextromethorphan 90 mg)

Comments:
-Each 5 mL contains promethazine 6.25 mg and dextromethorphan 15 mg.
-Extra caution is advised with use of promethazine in children as respiratory depression is strongly associated with use; however, its occurrence is not directly related to individualized weight base dosing.

Use: For the temporary relief of coughs and upper respiratory symptoms associated with allergy or the common cold.

Renal Dose Adjustments

Data not available

Liver Dose Adjustments

Use with caution

Dose Adjustments

Elderly: Dose selection should be cautious, usually starting the low end of the dosing range.

Precautions

US BOXED WARNING: POTENTIALLY FATAL RESPIRATORY DEPRESSION IN CHILDREN LESS THAN 2 YEARS OF AGE:
-Promethazine should not be used in pediatric patients less than 2 years of age because of the potential for fatal respiratory depression. In postmarketing cases of respiratory depression, which have included fatalities, a wide range of weight-based doses have resulted in respiratory depression in these patients.
-Caution should be exercised when administering promethazine to pediatric patients 2 years of age and older. It is recommended that the lowest effective dose of promethazine be used and concomitant administration of other drugs with respiratory depressant effects be avoided.

Safety and efficacy have not been established in patients younger than 2 years.

Consult WARNINGS section for additional precautions.

Dialysis

Data not available

Other Comments

Administration advice:
-Take orally as directed; do not exceed recommended doses
-Use calibrated measuring device; a household spoon is not an accurate measuring device

Storage requirements:
-Protect from light; keep tightly closed
-Store at 20C to 25C (68F to 77F)

General:
-A wide range of promethazine weight-based doses have resulted in respiratory depression in pediatric patients; administration with other respiratory depressants has been associated with respiratory depression and sometimes death in pediatric patients.
-An increased susceptibility to dystonia has been observed in children who are acutely ill and also dehydrated.
-Hallucinations and convulsions have occurred with therapeutic doses of promethazine in pediatric patients.
-Dextromethorphan should be used cautiously in patients confined to the supine position.

Monitoring:
-Monitor for excessive sedation
-Monitor for respiratory depression
-Monitor for involuntary movements

Patient advice:
-Patients should be advised this drug may cause marked drowsiness and impair the mental and/or physical abilities required for driving or operating machinery; concomitant use of alcohol and other CNS depressants should be avoided.
-Patients should be instructed to report any involuntary muscle movements.
-Patients should be instructed to avoid prolonged sun exposure.
-Patients should be made aware that fatal respiratory depression has occurred in pediatric patients and use in pediatric patients should be undertaken with extreme caution.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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