Promethazine

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 narcotic 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.

Promethazine is available under the following different brand names: Phenergan, and Phenadoz.

Dosages of Promethazine:

Adult Dosage Forms and Strengths

Tablet

• 12.5 mg
• 25 mg
• 50 mg

Suppository

• 12.5 mg
• 25 mg
• 50 mg

Injectable solution

• 25 mg/mL
• 50 mg/mL

Syrup

• 6.25 mg/5 mL

Dosing Considerations – Should be Given as Follows:

Allergic Conditions

• Taken orally or rectally: 25 mg at bedtime or 12.5 mg before meals and at bedtime (dosage range, 6.25-12.5 mg once every 8 hours)
• Intravenously (IV)/intramuscularly (IM): 25 mg; may be repeated in 2 hours when necessary; switch to oral dosing as soon as possible

Nausea and Vomiting

• Taken orally or rectally: 12.5-25 mg once every 4-6 hours as needed
• Intravenously (IV)/intramuscularly (IM): 12.5-25 mg once every 4-6 hours as needed

Motion Sickness

• 25 mg taken orally or rectally 30-60 minutes before departure and once every 8-12 hours as needed; on succeeding travel days, 25 mg orally or rectally every morning and every evening

Preoperative Sedation

• 50 mg taken orally or rectally on the night before procedure or 25-50 mg intravenously (IV)/intramuscularly (IM) combined with reduced doses of analgesics and atropine-like drugs

Postoperative Sedation

• 25-50 mg intravenously/intramuscularly/orally/rectally combined with reduced doses of analgesics and atropine-like drugs

Obstetric Sedation

• 25-50 mg intravenously (IV)/intramuscularly (IM) in early labor; may be increased to 25-75 mg once every 2-4 hours after labor established; not to exceed two doses or up to 100 mg/day during labor

Allergic Conditions (Off-label)

• Children under 2 years old: Contraindicated
• Children 2 years and older: 25 mg taken orally or rectally at bedtime or 12.5 mg once every 6 hours; alternatively, 6.25-12.5 mg orally/rectally once every 8 hours

Nausea & Vomiting

• Children under 2 years old: Contraindicated
• Children 2 years and older: 0.25-1 mg/kg orally/rectally once every 4-6 hours as needed; not to exceed 25 mg

Motion Sickness

• Children under 2 years: Contraindicated
• Children 2 years and older: 12.5-25 mg orally/rectally administered 30-60 minutes before departure and once every 8-12 hours as needed or 0.5 mg/kg orally once every 12 hours as needed
• Succeeding days of travel: 12.5-25 mg twice daily (upon arising or before evening meals)

Sedation

• Children under 2 years: Contraindicated
• Children 2 years and older: 12.5-25 mg orally/intramuscularly/rectally at bedtime

Preoperative Sedation

• Children under 2 years: Contraindicated
• Children 2 years and older: 1 mg/kg orally or rectally with a reduced dose of analgesic and appropriate dose of an atropine-like drug

Postoperative Sedation

• Children under 2 years: Contraindicated
• Children 2 years and older: 12.5-25 mg with a reduced dose of analgesic and appropriate dose of an atropine-like drug

Common Side effects of Promethazine include:

• Sedation
• Confusion
• Disorientation
• Blurred vision
• Hallucinations
• Muscle spasms
• Catatonic states
• Euphoria
• Excitation
• Extrapyramidal symptoms (tremors, jerky movements, muscle rigidity)
• Fast or slow heart rate
• Photosensitivity
• Obstructive jaundice
• Dry mouth
• Skin swelling (angioneurotic edema)
• Involuntary movements (tardive dyskinesia)
• Hives
• Angioneurotic edema
• Impotence
• Urinary retention

Rare side effects of promethazine include

• Leukopenia
• Agranulocytosis

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

If your doctor has directed you to use this medication, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

Severe Interactions of promethazine include:

• astemizole
• cisapride
• disopyramide
• ibutilide
• indapamide
• metrizamide
• pentamidine
• pimozide
• procainamide
• quinidine
• sotalol
• terfenadine

Promethazine has serious interactions with at least 59 different drugs.

Promethazine has moderate interactions with at least 290 different drugs.

Promethazine has mild interactions with at least 69 different drugs.

This information does not contain all possible interactions or adverse effects. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns, or for more information about this medicine.

Warnings

• IV administration can cause severe tissue injury, including burning, gangrene, or thrombophlebitis, necessitating fasciotomy, skin graft, or amputation
• Severe tissue injury can occur from perivascular extravasation, unintentional intra-arterial injection, and intraneuronal or perineuronal infiltration
• Deep IM injection is the preferred method of administration
• Intra-arterial and SC administration is contraindicated
• 25 mg/mL product may be administered by deep IM injection or IV infusion (at a rate not to exceed 25 mg/min through flowing IV tubing)
• Monitor for signs and symptoms of potential tissue injury including burning or pain at the site of injection, phlebitis, swelling, and blistering
• Discontinue IV infusion immediately if the patient complains of pain during injection
• Respiratory fatalities reported with use in children less than 2 years (use contraindicated); use lowest effective dose in children 2 years and older; avoid other drugs with respiratory depressant effects
• This medication contains promethazine
• Do not take Phenergan or Phenadoz if you are allergic to promethazine or any ingredients contained in this drug
• Keep out of reach of children
• In case of overdose, get medical help or contact a Poison Control Center immediately

Contraindications

• Hypersensitivity
• Newborn/premature infants less than 2 years old (risk of potentially fatal respiratory depression)
• SC or intra-arterial administration
• Coma
• Treatment of lower respiratory tract symptoms, including asthma

Effects of Drug Abuse

• No information available

Short-Term Effects

• See "What Are Side Effects Associated with Using Promethazine?"

Long-Term Effects

• See "What Are Side Effects Associated with Using Promethazine?"

Cautions

• Use caution in asthma, hepatic impairment, peptic ulcer disease, respiratory impairment, bone marrow suppression, anaphylaxis in susceptible individuals
• May impair ability to drive or perform hazardous tasks
• May impair core body temperature regulation; caution when taking medications with anticholinergic effects, heat exposure, or strenuous exercise
• Depresses hypothalamic thermoregulatory mechanism; exposure to extreme temperatures may cause hypo- or hyperthermia
• May alter cardiac conduction (life-threatening arrhythmias reported)
• The antiemetic effect may obscure the toxicity of chemotherapeutic drugs
• Monitor closely in patients with cardiovascular disease, hepatic impairment, Reye syndrome, or history of sleep apnea
• Has anticholinergic effects; use with caution in patients with decreased gastrointestinal motility or obstructions (partial or complete), urinary retention, urinary obstructions, xerostomia, BPH, or visual problems
• May cause extrapyramidal symptoms including pseudoparkinsonism, acute dystonic reactions, tardive dyskinesia, and akathisia
• Neuroleptic malignant syndrome reported with use; monitor for fever, muscle rigidity and/or autonomic instability, or mental status changes
• May cause orthostatic hypotension; use caution in patients at risk of experiencing hypotensive episodes (cardiovascular disease, cerebrovascular disease, hypovolemia, or taking medications that may predispose to bradycardia or hypotension)
• May cause photosensitivity
• Pyloroduodenal obstruction, stenosing peptic ulcer disease, or bladder neck obstruction
• Anticholinergic effects of promethazine may exacerbate the condition in patients with narrow-angle glaucoma or myasthenia gravis

Pregnancy and Lactation

• Use promethazine with caution if benefits outweigh risks
• Animal studies show risk and human studies not available or neither animal nor human studies done
• It is not known whether promethazine crosses into breast milk; discontinue the drug, or do not nurse while using promethazine