Frequently Asked Questions

Promethazine is a type of medicine called a sedating antihistamine. Phenergan is the brand name of Promethazine that works by preventing the actions of histamine.

Where Is Promethazine Used?

Promethazine is an antihistamine used to treat allergic reactions and to treat or prevent nausea and vomiting from illness or motion sickness. It is also used to make you sleep before surgery, and to help treat pain or nausea after surgery.

How Does Promethazine Work?

For Allergies

Histamine is a substance made by the body as part of its defense mechanisms. It causes the symptoms of allergic reactions such as inflammation in the nose or airways, rashes, and itching of the eyes, nose, throat, or skin. Promethazine blocks histamine from binding to its receptors in various parts of the body and this prevents it from causing the symptoms of an allergic reaction.

For Travel Sickness

Promethazine also blocks histamine receptors in a zone of the brain called the vomiting center. It is activated when it gets nerve messages from a part of the inner ear called the vestibular apparatus. It’s accountable for making you feel sick and for the vomiting reflex. Promethazine stops the vomiting center from being activated.

For Sleep

Promethazine is known as a sedating antihistamine as it enters the brain in substantial quantities and makes you feel sleepy. You can use it for short periods to help you get to sleep if you’re having trouble sleeping.

Recommended Dosage for Promethazine

• The dose of Promethazine that is needed and how often the medication needs to be taken will depend on the condition being treated and the age of the person being treated. It is important to follow the instructions in the leaflet or packaging provided with this medicine, or the instructions are given by your doctor.
• Do not exceed the recommended dose.
• Take this medicine by mouth. Use a specially marked spoon or container to measure your medicine. Ask your pharmacist if you do not have one.
• Take your doses at regular intervals. Do not take your medicine more often than directed.
• If symptoms persist despite treatment, seek medical advice from your doctor or pharmacist.

Possible Side Effects of Promethazine

Common side effects:

• Stuffy nose
• Headache

Side effects that you should report to your doctor as soon as possible:

• Blurred vision
• Irregular heartbeat or chest pain
• Muscle or facial twitches
• Pain or difficulty passing urine
• Skin rash
• Slowed or shallow breathing
• Unusual bleeding or bruising

Precautions While Taking Promethazine

• Tell your doctor if your symptoms do not start to get better in 2 or more days.
• You may get drowsy or dizzy. Do not drive, use machinery, or do anything that needs mental alertness until you know how this medicine affects you.
• This medicine can make you more sensitive to the sun. Keep out of the sun.
• If you are diabetic, check your blood sugar levels regularly.
• If you are pregnant or breastfeeding, you should consult your doctor first.