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Promethazine Patient Tips

Medically reviewed by C. Fookes, BPharm. Last updated on Sep 15, 2017.

How it works

  • Promethazine works on histamine receptors to relieve allergy symptoms. It can also be used to treat nausea and motion sickness. Promethazine may have weak effects at other receptors (such as dopamine).
  • Promethazine belongs to the class of medicines known as phenothiazines.


  • May be used in the treatment of rhinitis (vasomotor and allergic), conjunctivitis due to allergies or foods, mild urticaria (itchy rash) and other allergic reactions. May also be used together with epinephrine for more severe allergic reactions (such as anaphylaxis) after the acute event has been controlled.
  • May be used for the prevention or treatment of motion sickness.
  • May be used as a sedative pre- or post-operatively or in women during labor. Relieves apprehension and produces a light sleep from which a person can be easily aroused.
  • May be used in the prevention and control of nausea associated with surgery or anesthesia.
  • Generic promethazine is available.


If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

  • Drowsiness, which may affect a person's ability to drive or operate machinery. Avoid alcohol.
  • Heart rate disturbances, dry mouth, confusion.
  • Rarely, respiratory depression (unusually slow and shallow breathing); children are more at risk. Avoid in children aged less than 2 years.
  • FD&C Yellow No. 5 (tartrazine) is contained in some products. This may cause allergic-type reactions (including bronchial asthma) in certain susceptible persons; people with an aspirin hypersensitivity may be more at risk.
  • Rarely may cause unusual symptoms such as oculogyric crisis (prolonged upward deviation of the eyes) torticollis (head involuntarily turned to one side) and tongue protrusion. Confusion, tinnitus (ringing in the ears), hyperexcitability and seizures have also been reported.
  • Occasionally, paradoxical reactions (the opposite of what is to be expected) may occur. Symptoms include excitability and nightmares. Children and elderly people may be more prone to these effects.
  • May interact with a number of other drugs including antidepressants, antipsychotics, and other drugs that cause sedation.

Notes: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. For a complete list of all side effects, click here.

Bottom Line

  • Promethazine may be used to relieve allergy symptoms and nausea. Sedation is the main side effect.


  • Administer without regard to meals. But if stomach upset occurs; administer with meals.
  • When used as a sedative, administer just before bedtime. When used to prevent motion sickness, administer 30 minutes to one hour before travel.
  • Available as tablets, solutions, syrups and suppositories. Use the lowest dose possible to relieve your symptoms. Do not take more than the recommended amount.
  • Do not use in children under the age of 2 years as a number of cases of respiratory depression (marked slow-down in breathing) have been reported, some fatal.
  • Caution when using in children over 2 years. Use the lowest possible dose under medical advice.
  • Avoid prolonged exposure to the sun.
  • Report any unusual muscle movements to a doctor.

Response and Effectiveness

  • Promethazine's effects are noticeable within 20 minutes of oral administration. Its effects last for 4-6 hours, although they may persist for up to 12 hours in some people.


Promethazine [Package Insert]. Revised 03/2017. Par Pharmaceutical

  • Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use promethazine only for the indication prescribed.

Copyright 1996-2018 Revision Date: 2017-11-21 00:28:48

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.