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Promethazine: General Information

Promethazine is a medication primarily used to treat allergies, coughing, nausea, and vomiting. It belongs to a class of drugs known as phenothiazines. Promethazine works by blocking the action of histamine, a substance in the body that causes allergic symptoms.


Promethazine is usually taken by mouth as directed by your doctor. It may be taken with or without food. If you are using the liquid form of this medication, measure the dose carefully using a special measuring device/spoon. Do not use a household spoon because you may not get the correct dose.


Before taking promethazine, inform your doctor or pharmacist if you are allergic to it or any other phenothiazines, or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.


Promethazine should not be used in children younger than 2 years because it may cause serious (possibly fatal) slow/shallow breathing. Promethazine should not be used in children younger than 16 years to treat nausea or vomiting related to surgery or certain medications unless directed by the doctor.

Possible Side Effects

Common side effects of promethazine include drowsiness, dizziness, constipation, blurred vision, or dry mouth/nose/throat. If any of these effects persist or worsen, inform your doctor promptly.

Drug Interactions

Promethazine may interact with other medications, including but not limited to, anticholinergic drugs, such as benztropine or trihexyphenidyl, certain drugs for Parkinson’s disease, such as levodopa or pergolide, among others. Before using promethazine, inform your doctor or pharmacist of all prescription and nonprescription/herbal products you may use.

See also  Allergic reactions(Coughing,Nausea,Vomiting)

Missed Dose

If you miss a dose, take it as soon as you remember. If it is near the time of your next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.


If overdose is suspected, contact a poison control center or emergency room immediately. Symptoms of overdose may include confusion, severe drowsiness/dizziness, fainting, fast/irregular heartbeat, or seizures.


Store promethazine at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.

Description of Its Role in Treating Allergic Reactions, Cough, Nausea, and Vomiting

Promethazine is effective in treating allergic reactions by blocking histamine, thus reducing symptoms such as itching, sneezing, and watery eyes. Additionally, it acts as a cough suppressant by suppressing the cough reflex. Promethazine also helps alleviate nausea and vomiting by blocking receptors in the brain that trigger these symptoms. Overall, it plays a crucial role in providing relief from various allergic reactions and symptoms associated with cough, nausea, and vomiting.