Indications
Promethazine Theoclate is an antihistamine used to prevent and treat nausea and vomiting, especially travel sickness (motion sickness) by car, bus, boat or air. It is also used for dizziness and sickness caused by inner ear problems (vertigo, Meniere’s disease) and, on a doctor’s advice, for severe sickness in pregnancy.
How It Works
It blocks histamine H1 receptors and also has anticholinergic effects. This calms the balance centre in the inner ear and the vomiting centre in the brain, reducing the signals that cause nausea, vomiting and dizziness. Its effect lasts a long time, so one dose often covers a whole day.
Dosage and Administration
Adults and children over 10 years: for travel sickness, usually 25 mg the night before a long journey or 1 to 2 hours before a short journey; it can be repeated every 24 hours if needed. For other nausea or vertigo, 25 mg once a day, up to 25 mg three times a day, as directed by your doctor. Do not take more than 100 mg in 24 hours. Children 5 to 10 years: usually half the adult dose, as directed on the label. Not for children under 2 years; for children 2 to 5 years use only on a doctor’s advice. Swallow with water.
Interactions
- Alcohol, sleeping pills, opioid painkillers, sedating antihistamines and anxiety medicines: increased drowsiness.
- MAO inhibitors and tricyclic antidepressants (such as Amitriptyline): stronger anticholinergic effects.
- Anticholinergic medicines (such as Atropine or Hyoscine): more dry mouth, constipation and urine retention.
- Metoclopramide and antipsychotics: higher risk of movement side effects.
Contraindications
Do not take if allergic to promethazine or other phenothiazines, in children under 2 years (risk of dangerous breathing problems), if you have taken an MAO inhibitor in the last 2 weeks, or if you are in a coma or have severe drowsiness from other substances.
Side Effects
- Drowsiness, tiredness, dizziness.
- Dry mouth, blurred vision, constipation, difficulty passing urine.
- Headache, restlessness or nightmares, especially in children.
- Sensitivity of the skin to sunlight.
Get urgent medical help for difficulty breathing, fits, a very fast or irregular heartbeat, high fever with stiff muscles and confusion, uncontrolled movements of the face or body, or swelling of the face and throat.
Pregnancy and Lactation
It may be used for severe sickness in pregnancy if a doctor advises it. Avoid in the last 2 weeks before delivery unless prescribed, as the newborn may be drowsy or irritable. Small amounts pass into breast milk; ask your doctor before use while breastfeeding.
Precautions and Warnings
It causes drowsiness, which may last into the next day; do not drive or use machines if affected, and avoid alcohol. Use with care in epilepsy, asthma, glaucoma, prostate enlargement, liver or kidney disease, heart disease and in the elderly. Avoid strong sunlight. Stop taking it at least 72 hours before allergy skin tests.
Overdose
Overdose may cause deep sleep, confusion, excitement (especially in children), fits, fast heartbeat and breathing problems. Get emergency medical help.
Therapeutic Class
Phenothiazine antihistamine; antiemetic.
Storage
Store below 30°C in a dry place, away from light and out of the reach of children.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.