Promethazine Side Effects

Medically reviewed by Drugs.com. Last updated on May 8, 2024.

Applies to promethazine: oral syrup, oral tablet.

Other dosage forms:

• rectal suppository
• solution

Important warnings This medicine can cause some serious health issues

Oral route (tablet; syrup; solution)

Promethazine hydrochloride should not be used in pediatric patients less than 2 years of age because of the potential for fatal respiratory depression.

Postmarketing cases of respiratory depression, including fatalities, have been reported with use of promethazine in pediatric patients less than 2 years of age.

A wide range of weight-based doses of promethazine have resulted in respiratory depression in these patients.

Caution should be exercised when administering promethazine to pediatric patients 2 years or age and older.

It is recommended that the lowest effective dose of promethazine be used in pediatric patients 2 years of age and older and concomitant administration of other drugs with respiratory depressant effects be avoided.

Serious side effects of promethazine

Along with its needed effects, promethazine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Stop taking promethazine and get emergency help immediately if any of the following effects occur:

Rare side effects

- Symptoms of neuroleptic malignant syndrome; two or more occur together; most of these effects do not require emergency medical attention if they occur alone

• convulsions (seizures)
• difficult or unusually fast breathing
• fast heartbeat or irregular pulse
• high fever
• high or low (irregular) blood pressure
• increased sweating
• loss of bladder control
• severe muscle stiffness
• unusually pale skin
• unusual tiredness or weakness

Check with your doctor immediately if any of the following side effects occur while taking promethazine:

Incidence not known

• abdominal or stomach pain
• black, tarry stools
• bleeding gums
• blood in urine or stools
• bloody nose
• blurred vision
• chest pain or discomfort
• chills
• clay-colored stools
• confusion as to time, place, or person
• cough or hoarseness
• dark urine
• decreased awareness or responsiveness
• difficulty or troubled breathing
• double vision
• fast, pounding, or irregular heartbeat or pulse
• fever with or without chills
• fixed position of eye
• headache
• heavier menstrual periods
• high fever
• holding false beliefs that cannot be changed by fact
• hyperexcitability
• increased or decreased blood pressure
• increased sweating
• irregular, fast or slow, or shallow breathing
• itching
• large, hive-like swelling on face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
• lightheadedness, dizziness, or fainting
• loss of appetite
• loss of bladder control
• lower back or side pain
• mimicry of speech or movements
• mutism
• nasal stuffiness
• nausea
• negativism
• nightmares
• noisy breathing
• not breathing
• painful or difficult urination
• pale or blue lips, fingernails, or skin
• peculiar postures or movements, mannerisms or grimacing
• pinpoint red spots on skin
• seeing double
• seeing, hearing, or feeling things that are not there
• seizures
• severe muscle stiffness
• severe sleepiness
• shortness of breath
• skin rash
• slow or irregular heartbeat
• sore throat
• sores, ulcers, or white spots on lips or in mouth
• sticking out of tongue
• swollen glands
• tightness in chest
• tremors
• uncontrolled twisting movements of neck
• unpleasant breath odor
• unusual bleeding or bruising
• unusual excitement, nervousness, or restlessness
• unusual tiredness or weakness
• vomiting of blood
• wheezing
• yellow eyes or skin

Symptoms of overdose

• discouragement
• dizziness, faintness, or lightheadedness when getting up from a lying or sitting position suddenly
• dry mouth
• excessive muscle tone
• feeling of warmth
• feeling sad or empty
• irritability
• lack of appetite
• loss of interest or pleasure
• muscle tension or tightness
• overactive reflexes
• pupils of eyes large and not moving or responding to light
• redness of the face, neck, arms and occasionally, upper chest
• shakiness and unsteady walk
• sudden death
• trouble concentrating
• trouble sleeping
• unconsciousness
• unsteadiness, trembling, or other problems with muscle control or coordination
• unusual paleness

Other side effects of promethazine

Some side effects of promethazine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Incidence not known

• blistering, crusting, irritation, itching, or reddening of skin
• continuing ringing or buzzing or other unexplained noise in ears
• cracked, dry, scaly skin
• dizziness
• drowsiness
• excitation
• false or unusual sense of well-being
• hearing loss
• hives or welts
• increased sensitivity of skin to sunlight
• lack of coordination
• loss of strength or energy
• muscle pain or weakness
• redness or other discoloration of skin
• relaxed and calm
• sunburn
• swelling
• unable to sleep
• vomiting

For healthcare professionals

Applies to promethazine: compounding powder, injectable solution, oral syrup, oral tablet, rectal suppository.

General adverse events

The most commonly reported side effect include drowsiness, dizziness, and restlessness.^[Ref]

Nervous system

• Frequency not reported: Drowsiness, sedation, somnolence, dizziness, extrapyramidal symptoms, incoordination, tremors, convulsive seizures, faintness, headache, neuroleptic malignant syndrome/fatal neuroleptic malignant syndrome, psychomotor impairment, antimuscarinic effects, abnormal movements, central nervous system depression, activation of epileptogenic foci, tardive dyskinesia, tic-like movements of the head and face^[Ref]

Local

• Frequency not reported: Severe chemical irritation, tissue damage, burning, pain, erythema, swelling, sensory loss, palsies, paralysis, severe spasm of distal vessels, thrombophlebitis, venous thrombosis, phlebitis, abscesses, tissue necrosis, gangrene^[Ref]

Psychiatric

• Frequency not reported: Restlessness, anxiety, confusion, disorientation, euphoria, nervousness, insomnia, catatonic-like states, irritability, hysteria, hallucinations, hyperexcitability, nightmares, delirium, agitation/agitated behavior^[Ref]

Gastrointestinal

• Frequency not reported: Dry mouth, nausea, vomiting, constipation, diarrhea, tongue protrusion, gastric irritation, epigastric distress^[Ref]

Cardiovascular

• Frequency not reported: Bradycardia, tachycardia, palpitations, hypotension, arrhythmias, circulatory collapse, increased or decreased blood pressure^[Ref]

Hematologic

• Frequency not reported: Leukopenia, thrombocytopenia, thrombocytopenic purpura, agranulocytosis, blood dyscrasias, hemolytic anemia, aplastic anemia^[Ref]

Dermatologic

• Frequency not reported: Dermatitis, photosensitivity, urticaria, rash, pruritus, angioneurotic edema, topical contact dermatitis^[Ref]

Other

• Frequency not reported: Lassitude, tinnitus, fatigue, tiredness, paradoxical reactions, decreased performance (impaired driving/poor work performance, incoordination, reduced motor skills, impaired information processing)^[Ref]

Respiratory

• Frequency not reported: Asthma, nasal stuffiness, respiratory depression/fatal respiratory depression, apnea/fatal apnea, marked irregular respiration^[Ref]

Ocular

• Frequency not reported: Blurred vision, oculogyric crisis, diplopia, angle closure glaucoma^[Ref]

Hypersensitivity

• Frequency not reported: Anaphylaxis, angioedema, hypersensitivity reactions^[Ref]

Musculoskeletal

• Frequency not reported: Torticollis, muscle spasms, muscle dyskinesia^[Ref]

Metabolic

• Frequency not reported: Anorexia, loss of appetite, appetite stimulation^[Ref]

Hepatic

• Frequency not reported: Jaundice, obstructive jaundice^[Ref]

Genitourinary

• Frequency not reported: Urinary retention and hesitancy^[Ref]

Frequently asked questions

• Par promethazine with codeine vs Hi-Tech promethazine with codeine?
• How long does promethazine stay in your system?

Further information

Promethazine side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.

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