Phenergan Side Effects

Generic name: promethazine

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

Note: This document provides detailed information about Phenergan Side Effects associated with promethazine. Some dosage forms listed on this page may not apply specifically to the brand name Phenergan.

Applies to promethazine: oral syrup, oral tablet.

Other dosage forms:

• rectal suppository
• solution

Precautions

It is very important that your doctor check your progress at regular visits to make sure this medicine is working properly. Blood tests may be needed to check for unwanted effects .

This medicine may affect blood sugar levels. If you notice a change in the results of your blood or urine sugar tests or if you have any questions, check with your doctor .

This medicine may cause some people to become dizzy, lightheaded, drowsy, or less alert than they are normally. Even if taken at bedtime, it may cause some people to feel drowsy or less alert on arising. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are not alert .

This medicine will add to the effects of alcohol and other CNS depressants (medicines that make you drowsy or less alert). Some examples of CNS depressants are antihistamines or medicine for hay fever, other allergies, or colds; sedatives, tranquilizers, antidepressants, or sleeping medicine; prescription pain medicine or narcotics; barbiturates; medicine for seizures; muscle relaxants; or anesthetics, including some dental anesthetics. Check with your medical doctor or dentist before taking any of the above while you are taking this medicine.

Check with your doctor right away if you have symptoms of pale or blue lips, fingernails, or skin; difficult or troubled breathing; irregular, fast, slow, or shallow breathing; or shortness of breath. These could be signs of a condition called respiratory depression .

Check with your doctor right away and stop taking your medicine (if directed by your doctor) if you have muscle stiffness, fever, difficult or fast breathing, seizures, fast heartbeat, increased sweating, loss of bladder control, unusually pale skin, or tiredness or weakness. These may be symptoms of a serious condition called neuroleptic malignant syndrome (NMS) .

Before you have any medical tests, tell the medical doctor in charge that you are taking this medicine. The results of some tests may be affected by this medicine .

This medicine may cause dryness of the mouth. For temporary relief, use sugarless candy or gum, melt bits of ice in your mouth, or use a saliva substitute. However, if your mouth continues to feel dry for more than 2 weeks, check with your medical doctor or dentist. Continuing dryness of the mouth may increase the chance of dental disease, including tooth decay, gum disease, and fungus infections .

This medicine may make your skin more sensitive to sunlight. Use a sunscreen when you are outdoors. Avoid sunlamps and tanning beds .

This medicine controls nausea and vomiting. For this reason, it may cover up some of the signs of overdose caused by other medicines or the symptoms of encephalopathy or Reye's syndrome. This will make it difficult for your doctor to diagnose these conditions. Make sure your doctor knows that you are taking this medicine .

Serious side effects of Phenergan

Along with its needed effects, promethazine (the active ingredient contained in Phenergan) 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:

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

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 Phenergan

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:

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]

See also:

Frequently asked questions

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

Further information

Phenergan 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.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer