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promethazine plain

Promethazine Plain (Promethazine Hydrochloride) is a phenothiazine used to treat Anaphylaxis, Allergic Conjunctivitis, Motion Sickness, Nausea.

Promethazine Hydrochloride · by Pharmobedient

Generic of Phenergan

⚠ FDA reports a current shortage of the injection form — availability differs between suppliers — see drug shortages →
Not yet rated· sourced from the FDA label
Rated against independent regulatory sources·Last updated June 7, 2026·How we rate
Verified againstopenFDANIH DailyMedRxClass

Key facts

Drug class
Phenothiazine
Form
Syrup
Strength
Promethazine Hydrochloride 6.25MG/5ML
Type
Prescription (Rx)
Brand or generic
Generic
Manufacturer
Pharmobedient
Half-life
about 9 to 16 hours (how long it stays in your system)
What the pharmacy pays
~$1.53 for 30 — not your price
FDA application
ANDA087953

What is Promethazine Plain?

From the FDA label:Each 5 mL (teaspoonful) of Promethazine contains 6.25 mg of promethazine HCl. The inactive ingredients present are artificial banana flavor, artificial fruit flavor, artificial strawberry flavor, ascorbic acid, citric acid anhydrous, dehydrated alcohol, D&C Yellow No. 10, edetate disodium, FD&C Blue No. 1, FD&C Red No. 40, glycerin, sucrose, methylparaben, purified water, saccharin sodium, sodium benzoate, sodium citrate dihydrate, and sodium propionate. Promethazine HCl is a racemic compound; the molecular formula is C17H20N2S•HCl and its molecular weight is 320.88. Promethazine HCl, a phenothiazine derivative, is designated chemically as 10H-Phenothiazine-10-ethanamine, N,N, -trimethyl-, monohydrochloride, (±)- with the following structural formula: Promethazine HCl occurs as a white to faint yellow, practically odorless, crystalline powder which slowly oxidizes and turns blue on prolonged exposure to air. It is freely soluble in water and soluble in alcohol. Image

How to use

Promethazine Syrup is contraindicated for children under 2 years of age (see WARNINGS-Black Box Warning and Use in Pediatric Patients ). Allergy The average oral dose is 25 mg taken before retiring; however, 12.5 mg may be taken before meals and on retiring, if necessary. Single 25-mg doses at bedtime or 6.25 to 12.5 mg taken three times daily will usually suffice. After initiation of treatment in children or adults, dosage should be adjusted to the smallest amount adequate to relieve symptoms. The administration of promethazine HCl in 25-mg doses will control minor transfusion reactions of an allergic nature. Motion Sickness The average adult dose is 25 mg taken twice daily. The initial dose should be taken one-half to one hour before anticipated travel and be repeated 8 to 12 hours later, if necessary. On succeeding days of travel, it is recommended that 25 mg be given on arising and again before the evening meal. For children, Promethazine Syrup, 12.5 to 25 mg, twice daily, may be administered. Nausea and Vomiting Antiemetics should not be used in vomiting of unknown etiology in children and adolescents (see WARNINGS-Use in Pediatric Patients ). The average effective dose of Promethazine for the active therapy of nausea and vomiting in children or adults is 25 mg. When oral medication cannot be tolerated, the dose should be given parenterally (cf. Promethazine Injection) or…

Side effects

Central Nervous System Drowsiness is the most prominent CNS effect of this drug. Sedation, somnolence, blurred vision, dizziness; confusion, disorientation, and extrapyramidal symptoms such as oculogyric crisis, torticollis, and tongue protrusion; lassitude, tinnitus, incoordination, fatigue, euphoria, nervousness, diplopia, insomnia, tremors, convulsive seizures, excitation, catatonic-like states, hysteria. Hallucinations have also been reported. Cardiovascular -Increased or decreased blood pressure, tachycardia, bradycardia, faintness. Dermatologic -Dermatitis, photosensitivity, urticaria. Hematologic -Leukopenia, thrombocytopenia, thrombocytopenic purpura, agranulocytosis. Gastrointestinal -Dry mouth, nausea, vomiting, jaundice. Respiratory -Asthma, nasal stuffiness, respiratory depression (potentially fatal) and apnea (potentially fatal). (See WARNINGS-Respiratory Depression .) Other -Angioneurotic edema. Neuroleptic malignant syndrome (potentially fatal) has also been reported. (See WARNINGS-Neuroleptic Malignant Syndrome .) Paradoxical Reactions Hyperexcitability and abnormal movements have been reported in patients following a single administration of promethazine HCl. Consideration should be given to the discontinuation of promethazine HCl and to the use of other drugs if these reactions occur. Respiratory depression, nightmares, delirium, and agitated behavior have…

FDA Boxed Warning (the FDA’s most serious warning)

Boxed (black-box) warning — from the FDA label

PROMETHAZINE 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 OF 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.

Warnings

Important safety information

Depression Promethazine Syrup may impair the mental and/or physical abilities required for the performance of potentially hazardous tasks, such as driving a vehicle or operating machinery. The impairment may be amplified by concomitant use of other central-nervous-system depressants such as alcohol, sedatives/hypnotics (including barbiturates), narcotics, narcotic analgesics, general anesthetics, tricyclic antidepressants, and tranquilizers; therefore such agents should either be eliminated or given in reduced dosage in the presence of promethazine HCl (see PRECAUTIONS-Information for Patients and Drug Interactions ). Respiratory Depression Promethazine Syrup may lead to potentially fatal respiratory depression. Use of Promethazine Syrup in patients with compromised respiratory function (e.g., COPD, sleep apnea) should be avoided. Lower Seizure Threshold Promethazine Syrup may lower seizure threshold. It should be used with caution in persons with seizure disorders or in persons who are using concomitant medications, such as narcotics or local anesthetics, which may also affect seizure threshold. Bone-Marrow Depression Promethazine Syrup should be used with caution in patients with bone-marrow depression. Leukopenia and agranulocytosis have been reported, usually when Promethazine (promethazine HCl) has been used in association with other known marrow-toxic agents. Neuroleptic Malignant Syndrome A potentially fatal symptom complex sometimes referred to as Neuroleptic Malignant Syndrome (NMS) has been reported in association with promethazine HCl alone or in combination with antipsychotic drugs. Clinical manifestations of NMS are hyperpyrexia, muscle rigidity, altered mental status and evidence of autonomic instability (irregular pulse or blood pressure, tachycardia, diaphoresis and cardiac dysrhythmias). The diagnostic evaluation of patients with this syndrome is complicated. In arriving at a diagnosis, it is important to identify cases where the clinical presentation includes both serious medical illness (e.g. pneumonia, systemic infection, etc.) and untreated or inadequately treated extrapyramidal signs and symptoms (EPS). Other important considerations in the differential diagnosis include central anticholinergic toxicity, heat stroke, drug fever and primary central nervous system (CNS) pathology. The management of NMS should include 1) immediate discontinuation of promethazine HCl, antipsychotic drugs, if any, and other drugs not essential to concurrent therapy, 2) intensive symptomatic treatment and medical monitoring, and 3) treatment of any concomitant serious medical problems for which specific treatments are available. There is no general agreement about specific pharmacological treatment regimens for uncomplicated NMS. Since recurrences of NMS have been reported with phenothiazines, the reintroduction of promethazine HCl should be carefully considered. Use in Pediatric Patients PROMETHAZINE SYRUP IS CONTRAINDICATED FOR USE IN PEDIATRIC PATIENTS LESS THAN TWO YEARS OF AGE. CAUTION SHOULD BE EXERCISED WHEN ADMINISTERING PROMETHAZINE SYRUP TO PEDIATRIC PATIENTS 2 YEARS OF AGE AND OLDER BECAUSE OF THE POTENTIAL FOR FATAL RESPIRATORY DEPRESSION. RESPIRATORY DEPRESSION AND APNEA, SOMETIMES ASSOCIATED WITH DEATH, ARE STRONGLY ASSOCIATED WITH PROMETHAZINE PRODUCTS AND ARE NOT DIRECTLY RELATED TO INDIVIDUALIZED WEIGHT-BASED DOSING, WHICH MIGHT OTHERWISE PERMIT SAFE ADMINISTRATION. CONCOMITANT ADMINISTRATION OF PROMETHAZINE PRODUCTS WITH OTHER RESPIRATORY DEPRESSANTS HAS AN ASSOCIATION WITH RESPIRATORY DEPRESSION, AND SOMETIMES DEATH, IN PEDIATRIC PATIENTS. ANTIEMETICS ARE NOT RECOMMENDED FOR TREATMENT OF UNCOMPLICATED VOMITING IN PEDIATRIC PATIENTS, AND THEIR USE SHOULD BE LIMITED TO PROLONGED VOMITING OF KNOWN ETIOLOGY. THE EXTRAPYRAMIDAL SYMPTOMS WHICH CAN OCCUR SECONDARY TO PROMETHAZINE SYRUP ADMINISTRATION MAY BE CONFUSED WITH THE CNS SIGNS OF UNDIAGNOSED PRIMARY DISEASE, e.g., ENCEPHALOPATHY OR REYE'S SYNDROME. THE USE OF PROMETHAZINE SYRUP SHOULD BE AVOIDED IN PEDIATRIC PATIENTS WHOSE SIGNS AND SYMPTOMS MAY SUGGEST REYE'S SYNDROME OR OTHER HEPATIC DISEASES. Excessively large dosages of antihistamines, including Promethazine Syrup, in pediatric patients may cause sudden death (see OVERDOSAGE ). Hallucinations and convulsions have occurred with therapeutic doses and overdoses of Promethazine in pediatric patients. In pediatric patients who are acutely ill associated with dehydration, there is an increased susceptibility to dystonias with the use of promethazine HCl. Other Considerations Administration of promethazine HCl has been associated with reported cholestatic jaundice. CNS Depression Promethazine Syrup may impair the mental and/or physical abilities required for the performance of potentially hazardous tasks, such as driving a vehicle or operating machinery. The impairment may be amplified by concomitant use of other central-nervous-system depressants such as alcohol, sedatives/hypnotics (including barbiturates), narcotics, narcotic analgesics, general anesthetics, tricyclic antidepressants, and tranquilizers; therefore such agents should either be eliminated or given in reduced dosage in the presence of promethazine HCl (see PRECAUTIONS-Information for Patients and Drug Interactions ). Respiratory Depression Promethazine Syrup may lead to potentially fatal respiratory depression. Use of Promethazine Syrup in patients with compromised respiratory function (e.g., COPD, sleep apnea) should be avoided. Lower Seizure Threshold Promethazine Syrup may lower seizure threshold. It should be used with caution in persons with seizure disorders or in persons who are using concomitant medications, such as narcotics or local anesthetics, which may also affect seizure threshold. Bone-Marrow Depression Promethazine Syrup should be used with caution in patients with bone-marrow depression. Leukopenia and agranulocytosis have been reported, usually when Promethazine (promethazine HCl) has been used in association with other known marrow-toxic agents. Neuroleptic Malignant Syndrome A potentially fatal symptom complex sometimes referred to as Neuroleptic Malignant Syndrome (NMS) has been reported in association with promethazine HCl alone or in combination with antipsychotic drugs. Clinical manifestations of NMS are hyperpyrexia, muscle rigidity, altered mental status and evidence of autonomic instability (irregular pulse or blood pressure, tachycardia, diaphoresis and cardiac dysrhythmias). The diagnostic evaluation of patients with this syndrome is complicated. In arriving at a diagnosis, it is important to identify cases where the clinical presentation includes both serious medical illness (e.g. pneumonia, systemic infection, etc.) and untreated or inadequately treated extrapyramidal signs and symptoms (EPS). Other important considerations in the differential diagnosis include central anticholinergic toxicity, heat stroke, drug fever and primary central nervous system (CNS) pathology. The management of NMS should include 1) immediate discontinuation of promethazine HCl, antipsychotic drugs, if any, and other drugs not essential to concurrent therapy, 2) intensive symptomatic treatment and medical monitoring, and 3) treatment of any concomitant serious medical problems for which specific treatments are available. There is no general agreement about specific pharmacological treatment regimens for uncomplicated NMS. Since recurrences of NMS have been reported with phenothiazines, the reintroduction of promethazine HCl should be carefully considered. Use in Pediatric Patients PROMETHAZINE SYRUP IS CONTRAINDICATED FOR USE IN PEDIATRIC PATIENTS LESS THAN TWO YEARS OF AGE. CAUTION SHOULD BE EXERCISED WHEN ADMINISTERING PROMETHAZINE SYRUP TO PEDIATRIC PATIENTS 2 YEARS OF AGE AND OLDER BECAUSE OF THE POTENTIAL FOR FATAL RESPIRATORY DEPRESSION. RESPIRATORY DEPRESSION AND APNEA, SOMETIMES ASSOCIATED WITH DEATH, ARE STRONGLY ASSOCIATED WITH PROMETHAZINE PRODUCTS…

Who should not take Promethazine Plain

Promethazine Syrup is contraindicated for use in pediatric patients less than two years of age. Promethazine Syrup is contraindicated in comatose states, and in individuals known to be hypersensitive or to have had an idiosyncratic reaction to promethazine or to other phenothiazines. Antihistamines are contraindicated for use in the treatment of lower respiratory tract symptoms including asthma.

Overdose — what happens if you take too much

Signs and symptoms of overdosage with promethazine HCl range from mild depression of the central nervous system and cardiovascular system to profound hypotension, respiratory depression, unconsciousness, and sudden death. Other reported reactions include hyperreflexia, hypertonia, ataxia, athetosis, and extensor-plantar reflexes (Babinski reflex). Stimulation may be evident, especially in children and geriatric patients. Convulsions may rarely occur. A paradoxical-type reaction has been reported in children receiving single doses of 75 mg to 125 mg orally, characterized by hyperexcitability and nightmares. Atropine-like signs and symptoms-dry mouth, fixed, dilated pupils, flushing, as well as gastrointestinal symptoms-may occur. Treatment Treatment of overdosage is essentially symptomatic and supportive. Only in cases of extreme overdosage or individual sensitivity do vital signs, including respiration, pulse, blood pressure, temperature, and EKG, need to be monitored. Activated charcoal orally or by lavage may be given, or sodium or magnesium sulfate orally as a cathartic. Attention should be given to the reestablishment of adequate respiratory exchange through provision of a patent airway and institution of assisted or controlled ventilation. Diazepam may be used to control convulsions. Acidosis and electrolyte losses should be corrected. Note that any depressant effects of…

U.S. Poison Control: call or text 1-800-222-1222 (free, 24/7). In an emergency call 911. From the FDA label; not medical advice.

Interactions

CNS Depressants Promethazine Syrup may increase, prolong, or intensify the sedative action of other central-nervous-system depressants, such as alcohol, sedatives/hypnotics (including barbiturates), narcotics, narcotic analgesics, general anesthetics, tricyclic antidepressants, and tranquilizers; therefore, such agents should be avoided or administered in reduced dosage to patients receiving promethazine HCl. When given concomitantly with Promethazine Syrup, the dose of barbiturates should be reduced by at least one-half, and the dose of narcotics should be reduced by one-quarter to one-half. Dosage must be individualized. Excessive amounts of promethazine HCl relative to a narcotic may lead to restlessness and motor hyperactivity in the patient with pain; these symptoms usually disappear with adequate control of the pain. Epinephrine Because of the potential for Promethazine to reverse epinephrine's vasopressor effect, epinephrine should NOT be used to treat hypotension associated with Promethazine Syrup overdose. Anticholinergics Concomitant use of other agents with anticholinergic properties should be undertaken with caution. Monoamine Oxidase Inhibitors (MAOI) Drug interactions, including an increased incidence of extrapyramidal effects, have been reported when some MAOI and phenothiazines are used concomitantly. This possibility should be considered with Promethazine Syrup. CNS Depressants Promethazine Syrup may increase, prolong, or intensify the sedative action of other central-nervous-system depressants, such as alcohol, sedatives/hypnotics (including barbiturates), narcotics, narcotic analgesics, general anesthetics, tricyclic antidepressants, and tranquilizers; therefore, such agents should be avoided or administered in reduced dosage to patients receiving promethazine HCl. When given concomitantly with Promethazine Syrup, the dose of barbiturates should be reduced by at least one-half, and the dose of narcotics should be reduced by one-quarter to one-half. Dosage must be individualized. Excessive amounts of promethazine HCl relative to a narcotic may lead to restlessness and motor hyperactivity in the patient with pain; these symptoms usually disappear with adequate control of the pain. Epinephrine Because of the potential for Promethazine to reverse epinephrine's vasopressor effect, epinephrine should NOT be used to treat hypotension associated with Promethazine Syrup overdose. Anticholinergics Concomitant use of other agents with anticholinergic properties should be undertaken with caution. Monoamine Oxidase Inhibitors (MAOI) Drug interactions, including an increased incidence of extrapyramidal effects, have been reported when some MAOI and phenothiazines are used concomitantly. This possibility should be considered with Promethazine Syrup.

How long does Promethazine Hydrochloride stay in your body?

The elimination half-life of promethazine hydrochloride is about 9 to 16 hours — the time it takes the body to clear about half of it. As a rule of thumb, a medicine is mostly gone after roughly 4 to 5 half-lives, though this varies from person to person with age and kidney or liver function. Kinetics are linear (no saturable/dose-dependent behavior). The FDA label reports a plasma half-life of 9-16 hours after IV dosing and a mean of 9.8 ± 3.4 hours after IM dosing; the oral tablet label omits a numeric half-life but describes the same disposition. Duration of clinical effect (about 4-6 hours, occasionally up to 12) is shorter than the elimination half-life, so sedation can wear off well before the drug clears. Promethazine is metabolized in the liver to sulfoxides of promethazine and N-desmethylpromethazine (the main urinary metabolites); the label does not characterize these as clinically active or as outlasting the parent. Not a prodrug. Because clearance is hepatic, impaired liver function may prolong the half-life; the label gives no specific age- or kidney-based half-life values.

This is general information, not medical advice. It doesn’t tell you when a drug test would read negative (tests detect substances for different, often longer, windows) or when it’s safe to take another dose — ask your pharmacist or prescriber. Source: Promethazine Hydrochloride Injection, USP — FDA label (DailyMed).

Drug class

May treat (source: NIH RxClass)

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Dosage forms

Syrup

The forms currently marketed in the U.S., per the FDA National Drug Code Directory.

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Frequently asked questions

What does Promethazine Plain treat?
Promethazine Plain (Promethazine Hydrochloride) may be used to treat anaphylaxis, allergic conjunctivitis, motion sickness, nausea, pain, postoperative complications, based on NIH RxClass drug-classification data (conditions a drug may treat — not a verbatim copy of the FDA-approved label). This is general reference, not medical advice.
How much does Promethazine Plain cost?
Nobody can tell you what you will pay — your price is set by your insurer's formulary, your deductible and the pharmacy's markup, and none of those are published. What IS published is what the pharmacy paid to acquire it: about $1.53 for 30, per the CMS NADAC survey. Treat that as the floor, not the quote — ask the pharmacist for the cash price as well as your copay, because for cheap generics the cash price often wins.
Is there a coupon or discount for Promethazine Plain?
pharmaranks is an independent ratings site, not a pharmacy — we don't issue coupons or sell Promethazine Plain. To pay less, Promethazine Plain is already a generic — usually the lowest-cost version — so the main levers are comparing cash prices between pharmacies and using a pharmacy discount-card service. Prices vary by pharmacy, insurance, and location, so always confirm at the counter. This is general reference, not medical or financial advice.
Who makes Promethazine Plain?
Promethazine Plain is marketed by Pharmobedient. You can see Pharmobedient's full profile, rating, and other products on pharmaranks.
Is Promethazine Plain a brand-name or generic drug?
Promethazine Plain is a generic medication; its active ingredient is Promethazine Hydrochloride. Generics contain the same active ingredient as the brand-name original and are usually lower cost.
Is Promethazine Plain available over the counter?
No. Promethazine Plain is a prescription (Rx) medication in the US — you need a prescription from a licensed clinician (in person or via telehealth); it isn't sold over the counter. For some conditions there are OTC alternatives — ask your pharmacist.
What forms does Promethazine Plain come in?
Promethazine Plain is currently marketed as syrup, per the FDA's National Drug Code Directory.
What class of drug is Promethazine Plain?
Promethazine Plain is classified as phenothiazine, per the FDA's Established Pharmacologic Class.
Is Promethazine Plain FDA-registered?
Promethazine Plain is on record with the U.S. FDA under application number ANDA087953. You can verify this on its official FDA label.
Is Promethazine Plain safe?
There's no single safe-or-not verdict, and we don't yet have a composite recall-safety score for Promethazine Plain. Review its FDA-label side effects and warnings below, and always consult a licensed professional.
What are the side effects of Promethazine Plain?
Promethazine Plain's side effects are taken directly from its FDA label. From the label: Central Nervous System Drowsiness is the most prominent CNS effect of this drug. Sedation, somnolence, blurred vision, dizziness; confusion, disorientation, and extrapyramidal symptoms such as oculogyric crisis, torticollis, and tongue protrusion; lassitude, tinnitus, incoordination, fatigue,… Both common and serious reactions are documented in full on this page. This is general reference from the FDA, not medical advice — always consult a professional.

Clinical content sourced from the FDA label via openFDA (U.S. FDA). View the FDA label on DailyMed → Provided for general reference only — not medical advice. Always consult a licensed professional and the current prescribing information.

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