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Promethazine

Brand names: Phenergan, Promethegan

Promethazine is a sedating antihistamine used for nausea, vomiting, motion sickness, and allergies.

Brand namesPhenergan, Promethegan
Type of medicineAntihistamine (nausea and allergy medicine)
Prescription?Prescription
ImportantThis page is general information, not a prescription. Don't start, stop, or change a medicine without talking to your provider or pharmacist.

Overview

It's also in some prescription cough syrups.

What it's used for

  • Nausea and vomiting
  • Motion sickness
  • Allergy symptoms
  • Sedation before procedures

How to take it

  • Take it with or without food.
  • For motion sickness, take it 30 to 60 minutes before travel.

Your dose depends on your health and other medicines. Always follow your prescription label, and ask your pharmacist if anything is unclear.

Side effects

Common side effects

  • Strong sleepiness
  • Dry mouth
  • Dizziness
  • Blurry vision
Call 911Slow, shallow, or stopped breathing, blue lips, or can't be woken up
Call 911High fever, stiff muscles, and confusion
Call your provider todayUncontrolled movements
Call your provider todaySevere pain, swelling, or skin color change at a shot site

Warnings

  • Boxed warning: never give it to children under 2; it can stop breathing.
  • Use caution in children 2 and older and in older adults.

Other medicines, foods, and alcohol

  • Opioids, alcohol, and sedating medicines can dangerously slow breathing.
  • Other anticholinergic medicines add to side effects.

Tell your provider and pharmacist about every medicine, vitamin, and supplement you take.

Pregnancy and breastfeeding

Sometimes used for nausea in pregnancy. Talk with your provider.

Missed doses, overdose, and storage

If you miss a dose

This medicine is often taken only when needed. If you take it on a schedule, take a missed dose when you remember, unless it's almost time for the next one. Don't double up.

If someone takes too much

Call Poison Control at 1-800-222-1222 or get help online at poison.org. Call 911 if the person collapses, has a seizure, has trouble breathing, or can't be woken.

Storing it

Store at room temperature, away from heat and moisture (not in the bathroom), and out of reach of children and pets.

Conditions it's used for

Sources

Last updated 2026-11-13.