About promethazine hcl
First-generation antihistamine; phenothiazine
Used for
- Relief of allergy symptoms, such as itching, sneezing, and runny nose
- Prevention or treatment of motion sickness
- Short-term relief of nausea and vomiting
Usual adult dose
Allergies: 25 mg at bedtime or 12.5 mg before meals and at bedtime. Motion sickness: 25 mg twice daily.
Usual dose in children
For allergies or motion sickness, dosing depends on age and weight. Not for children under 2 years; use only with clinician-directed dosing.
Common side effects
- Drowsiness, dizziness, and impaired coordination
- Dry mouth, blurred vision, or constipation
- Confusion or agitation, especially in older adults
Important warnings
- Can cause severe or fatal breathing problems in children under 2 years.
- May cause marked sleepiness; avoid alcohol and hazardous activities.
- Use caution with breathing disorders, glaucoma, urinary problems, or older age.
- Seek urgent help for trouble breathing, severe confusion, or uncontrolled movements.
Pregnancy
Use only when clearly needed; discuss potential risks and benefits with a healthcare professional.
Breastfeeding
May cause infant drowsiness or irritability and may reduce milk supply; seek professional guidance.
Interactions
- Alcohol, opioids, sleeping medicines, and sedatives increase drowsiness and breathing risks.
- Anticholinergic medicines can worsen dry mouth, blurred vision, constipation, or urinary retention.
- Some medicines that prolong the QT interval may increase abnormal heart rhythm risk.
AI-generated from general medical knowledge, not from this product's official leaflet. It may be incomplete or out of date. Not medical advice — ask a pharmacist or doctor before making any decision.