Take orally, with or without food. To minimize stomach upset, it may be taken with food or milk.

Promethazine acts as an H1-receptor antagonist, blocking histamine's effects. Its antiemetic effect is primarily due to its antagonism of dopamine D2 receptors in the chemoreceptor trigger zone (CTZ) and anticholinergic effects. Its sedative effects are due to its ability to cross the blood-brain barrier and block H1 receptors in the CNS.

• •Hypersensitivity to promethazine or other phenothiazines
• •Comatose states or severe CNS depression
• •Children under 2 years of age (due to risk of fatal respiratory depression)
• •Patients with severe respiratory impairment (e.g., severe asthma, COPD)
• •Angle-closure glaucoma, prostatic hypertrophy with urinary retention

Store in a cool, dry place below 30°C. Protect from light and moisture. Keep out of reach of children.

Symptoms of overdose include severe drowsiness, confusion, disorientation, severe dry mouth, blurred vision, dilated pupils, fever, hallucinations, convulsions, and respiratory depression. Management involves supportive care, maintaining airway, and treating symptoms.

Pregnancy Category C. Not recommended for use during late pregnancy or labor as it may cause respiratory depression in the newborn. Avoid during lactation as promethazine may pass into breast milk and cause drowsiness or irritability in the infant.