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Drug

Promethazine

Pronounced

"pro-METH-uh-zeen"

Uses

See also Warning section.

Promethazine is used to prevent and treat nausea and vomiting related to certain conditions (such as motion sickness, or before/after surgery). It is also used to treat allergy symptoms such as rash, itching, and runny nose. It may be used to help you feel sleepy/relaxed before and after surgery or to help certain opioid pain relievers (such as meperidine) work better. The suppository form is used when medications cannot be taken by mouth.

Promethazine is an antihistamine and works by blocking a certain natural substance (histamine) that your body makes during an allergic reaction. Its other effects (such as anti-nausea, calming, pain relief) may work by affecting other natural substances (such as acetylcholine) and by acting directly on certain parts of the brain.

Warning

Promethazine should not be used by children younger than 2 years because it may cause serious (possibly fatal) slow/shallow breathing. When this medication is used by children 2 years and older, the lowest effective dosage should be used, and other drugs that affect breathing should be avoided. Get medical help right away if slow/shallow breathing occurs.

In children, drugs for nausea should only be used in cases of prolonged vomiting of a known cause. Avoid use of promethazine in children with liver disease (including possible Reye's syndrome).

How to Use This Medication

Unwrap and insert one suppository rectally as directed by your doctor, usually 2 to 4 times daily. Remain lying down for a few minutes after using this medication, and avoid having a bowel movement for an hour or longer so the drug will be absorbed. The suppository is for rectal use only.

For motion sickness, the first dose of promethazine should be used 30 to 60 minutes before beginning travel. For allergies, this medication may be used once daily at bedtime to avoid being drowsy during the day. When used before surgery, promethazine may be used the night before or just before the procedure and may be continued afterwards as directed.

The dosage is based on your age, medical condition, and response to treatment. Children's dosage may also be based on weight. Do not increase your dose or use this medication more often than directed.

Tell your doctor if your condition does not get better or if it gets worse.

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Information expires December 2025.