DOSAGE AND ADMINISTRATION Promethazine Hydrochloride Tablets USP are contraindicated for children under 2 years of age (see WARNINGS-Black Box Warning and Use in Pediatric Patients ). Allergy The average oral dose is 25 mg taken before retiring; however, 12.5 mg may be taken before meals and on retiring, if necessary. Single 25-mg doses at bedtime or 6.25 to 12.5 mg taken three times daily will usually suffice. After initiation of treatment in children or adults, dosage should be adjusted to the smallest amount adequate to relieve symptoms. The administration of promethazine HCl in 25-mg doses will control minor transfusion reactions of an allergic nature. Motion Sickness The average adult dose is 25 mg taken twice daily. The initial dose should be taken one-half to one hour before anticipated travel and be repeated 8 to 12 hours later, if necessary. On succeeding days of travel, it is recommended that 25 mg be given on arising and again before the evening meal. For children, promethazine hydrochloride tablets, syrup, or rectal suppositories, 12.5 to 25 mg twice daily, may be administered. Nausea and Vomiting Antiemetics should not be used in vomiting of unknown etiology in children and adolescents (see WARNINGS-Use in Pediatric Patients ). The average effective dose of promethazine hydrochloride for the active therapy of nausea and vomiting in children or adults is 25 mg. When oral medication cannot be tolerated, the dose should be given parenterally (cf. Promethazine Injection) or by rectal suppository. 12.5- to 25-mg doses may be repeated, as necessary, at 4- to 6-hour intervals. For nausea and vomiting in children, the usual dose is 0.5 mg per pound of body weight, and the dose should be adjusted to the age and weight of the patient and the severity of the condition being treated. For prophylaxis of nausea and vomiting, as during surgery and the postoperative period, the average dose is 25 mg repeated at 4- to 6-hour intervals, as necessary. Sedation This product relieves apprehension and induces a quiet sleep from which the patient can be easily aroused. Administration of 12.5 to 25 mg promethazine hydrochloride by the oral route or by rectal suppository at bedtime will provide sedation in children. Adults usually require 25 to 50 mg for nighttime, presurgical, or obstetrical sedation. Pre- and Postoperative Use Promethazine hydrochloride in 12.5- to 25-mg doses for children and 50-mg doses for adults the night before surgery relieves apprehension and produces a quiet sleep. For preoperative medication, children require doses of 0.5 mg per pound of body weight in combination with an appropriately reduced dose of narcotic or barbiturate and the appropriate dose of an atropine-like drug. Usual adult dosage is 50 mg promethazine HCl with an appropriately reduced dose of narcotic or barbiturate and the required amount of a belladonna alkaloid. Postoperative sedation and adjunctive use with analgesics may be obtained by the administration of 12.5 to 25 mg in children and 25- to 50-mg doses in adults. Promethazine hydrochloride tablets are contraindicated for children under 2 years of age.