Promethazine

Promethazine is a sedating (first generation) antihistamine. It has a wide range of uses including treating allergic conditions, inducing sedation, short-term management of insomnia, treating nausea and vomiting, and preventing and treating motion sickness. Antihistamines can also be used to manage the symptoms of the common cold such as runny nose and sneezing. Promethazine relieves symptoms of itching, runny nose, watery eyes and sneezing.

In Hong Kong, it is frequently found in combination products used for treating coughs and colds.

The oral doses for different age groups and uses are listed below:

For allergic conditions

Adult
As Promethazine HCl: 25 mg at night, increase if necessary to 25 mg twice daily OR 10-20 mg 2-3 times daily.

Child 2-5 years
As Promethazine HCl: 5-15 mg daily in 1-2 divided doses.

Child 5-10 years
As Promethazine HCl: 10-25 mg daily in 1-2 divided doses.

For short-term management of insomnia

Adult
As Promethazine HCl: 20-50 mg at night.

For nausea and vomiting

Adult
As Promethazine teoclate: 25 mg at night, may increase the dose to 50-75 mg at night or to 25 mg 2-3 times daily if necessary up to a maximum of 100 mg daily.

For prevention of motion sickness

Adult
As Promethazine HCl: 20 or 25 mg the night before travelling and repeat in the next morning if necessary.

As Promethazine teoclate: 25 mg at night or 1-2 hour before travelling.

Child 2-5 years
As Promethazine HCl: 5 mg the night before the journey and repeat in the next morning (after 6-8 hours) if necessary.

Child 5-10 years
As Promethazine HCl: 10 mg the night before the journey and repeat in the next morning (after 6-8 hours) if necessary.

As Promethazine teoclate: 12.5 mg the night or 1-2 hour before travelling.

Common side effects of Promethazine include dizziness and drowsiness, constipation, blurred vision, and dry mouth.

• People with an allergy to Promethazine or other ingredients of the formulation
• Children under the age of 2

In Hong Kong, Promethazine is an over-the-counter medicine which can be purchased without a prescription from any retail outlet in Hong Kong. This includes grocery stores, convenience stores, medicine shops, and pharmacies. It can also be obtained from doctors. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health.

For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at https://www.drugoffice.gov.hk