Diphenhydramine Hydrochloride Injection, Usp

Diphenhydramine Hydrochloride Injection, Usp
SPL v1
SPL
SPL Set ID 5bbbd6e5-4d0a-4380-bbd3-3313ff26cda0
Routes
INTRAMUSCULAR INTRAVENOUS
Published
Effective Date 2025-12-18
Document Type 34391-3 HUMAN PRESCRIPTION DRUG LABEL

Drug Facts

Composition & Product

Active Ingredients
Diphenhydramine (50 mg)
Inactive Ingredients
Hydrochloric Acid Sodium Hydroxide Water

Identifiers & Packaging

Marketing Status
ANDA Active Since 2025-12-18

Description

Diphenhydramine Hydrochloride Injection, USP  is a sterile, nonpyrogenic solution for intravenous or deep intramuscular use as an antihistaminic agent. Each mL contains diphenhydramine hydrochloride 50 mg in Water for Injection. pH 4.0 to 6.5; sodium hydroxide and/or hydrochloric acid added, if needed, for pH adjustment. The chemical name of diphenhydramine hydrochloride is 2-(Diphenylmethoxy)-N,N-dimethylethylamine hydrochloride. The structural formula is as follows: C 17 H 21 NO • HCl MW 291.82 Diphenhydramine hydrochloride occurs as a white crystalline powder and is freely soluble in water and alcohol.

Indications and Usage

Diphenhydramine hydrochloride injection, USP is effective in adults and pediatric patients, other than premature infants and neonates, for the following conditions when the oral form is impractical. Antihistaminic For amelioration of allergic reactions to blood or plasma, in anaphylaxis as an adjunct to epinephrine and other standard measures after the acute symptoms have been controlled and for other uncomplicated allergic conditions of the immediate type when oral therapy is impossible or contraindicated. Motion Sickness For active treatment of motion sickness. Antiparkinsonism For use in parkinsonism, when oral therapy is impossible or contraindicated, as follows: parkinsonism in the elderly who are unable to tolerate more potent agents, mild cases of parkinsonism in other age groups and in other cases of parkinsonism in combination with centrally acting anticholinergic agents.

Dosage and Administration

THIS PRODUCT IS FOR INTRAVENOUS OR INTRAMUSCULAR ADMINISTRATION ONLY. Diphenhydramine hydrochloride injection, USP is indicated when the oral form is impractical. DOSAGE SHOULD BE INDIVIDUALIZED ACCORDING TO THE NEEDS AND THE RESPONSE OF THE PATIENT. Pediatric Patients, Other Than Premature Infants and Neonates 5 mg/kg/24 hours or 150 mg/m 2 /24 hours. Maximum daily dosage is 300 mg. Divide into four doses, administered intravenously at a rate generally not exceeding 25 mg/min, or deep intramuscularly. Adults 10 mg to 50 mg intravenously at a rate generally not exceeding 25 mg/min, or deep intramuscularly; 100 mg if required; maximum daily dosage is 400 mg. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.

Contraindications

Use in Neonates or Premature Infants This drug should not be used in neonates or premature infants. Use in Nursing Mothers Because of the higher risk of antihistamines for infants generally, and for neonates and prematures in particular, antihistamine therapy is contraindicated in nursing mothers. Use as a Local Anesthetic Because of the risk of local necrosis, this drug should not be used as a local anesthetic. Antihistamines are also Contraindicated in the Following Conditions Hypersensitivity to diphenhydramine hydrochloride and other antihistamines of similar chemical structure.

Adverse Reactions

The most frequent adverse reactions are italicized. General Urticaria; drug rash; anaphylactic shock; photosensitivity; excessive perspiration; chills; dryness of mouth, nose and throat. Cardiovascular System Hypotension, headache, palpitations, tachycardia, extrasystoles. Hematologic System Hemolytic anemia, thrombocytopenia, agranulocytosis. Nervous System Sedation , sleepiness , dizziness , disturbed coordination , fatigue, confusion, restlessness, excitation, nervousness, tremor, irritability, insomnia, euphoria, paresthesia, blurred vision, diplopia, vertigo, tinnitus, acute labyrinthitis, neuritis, convulsions. Gastrointestinal System Epigastric distress , anorexia, nausea, vomiting, diarrhea, constipation. Genitourinary System Urinary frequency, difficult urination, urinary retention, early menses. Respiratory System Thickening of bronchial secretions , tightness of chest and wheezing, nasal stuffiness.

Drug Interactions

Diphenhydramine hydrochloride has additive effects with alcohol and other CNS depressants (hypnotics, sedatives, tranquilizers, etc.) MAO inhibitors prolong and intensify the anticholinergic (drying) effects of antihistamines.

How Supplied

Diphenhydramine Hydrochloride Injection, USP 50 mg/mL is a sterile, nonpyrogenic, clear colourless solution, and is supplied as 1 mL single dose vial in package of 25s NDC: 70518-4536-00 NDC: 70518-4536-01 PACKAGING: 25 in 1 PACKAGE PACKAGING: 1 mL in 1 VIAL,GLASS Type 0 Storage Discard unused portion Protect from light. Keep covered in carton until time of use. Store at 20° to 25°C (68° to 77°F); excursions permitted between 15° to 30°C (59° to 86°F) [See USP Controlled Room Temperature]. To report SUSPECTED ADVERSE REACTIONS, contact Avet Pharmaceuticals Inc. at 1-866-901-DRUG (3784), or the FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. Repackaged and Distributed By: Remedy Repack, Inc. 625 Kolter Dr. Suite #4 Indiana, PA 1-724-465-8762


Medication Information

Indications and Usage

Diphenhydramine hydrochloride injection, USP is effective in adults and pediatric patients, other than premature infants and neonates, for the following conditions when the oral form is impractical.

Antihistaminic

For amelioration of allergic reactions to blood or plasma, in anaphylaxis as an adjunct to epinephrine and other standard measures after the acute symptoms have been controlled and for other uncomplicated allergic conditions of the immediate type when oral therapy is impossible or contraindicated.

Motion Sickness

For active treatment of motion sickness.

Antiparkinsonism

For use in parkinsonism, when oral therapy is impossible or contraindicated, as follows: parkinsonism in the elderly who are unable to tolerate more potent agents, mild cases of parkinsonism in other age groups and in other cases of parkinsonism in combination with centrally acting anticholinergic agents.

Dosage and Administration

THIS PRODUCT IS FOR INTRAVENOUS OR INTRAMUSCULAR ADMINISTRATION ONLY.

Diphenhydramine hydrochloride injection, USP is indicated when the oral form is impractical.

DOSAGE SHOULD BE INDIVIDUALIZED ACCORDING TO THE NEEDS AND THE RESPONSE OF THE PATIENT.

Pediatric Patients, Other Than Premature Infants and Neonates

5 mg/kg/24 hours or 150 mg/m 2/24 hours. Maximum daily dosage is 300 mg. Divide into four doses, administered intravenously at a rate generally not exceeding 25 mg/min, or deep intramuscularly.

Adults

10 mg to 50 mg intravenously at a rate generally not exceeding 25 mg/min, or deep intramuscularly; 100 mg if required; maximum daily dosage is 400 mg.

Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.

Contraindications

Use in Neonates or Premature Infants

This drug should not be used in neonates or premature infants.

Use in Nursing Mothers

Because of the higher risk of antihistamines for infants generally, and for neonates and prematures in particular, antihistamine therapy is contraindicated in nursing mothers.

Use as a Local Anesthetic

Because of the risk of local necrosis, this drug should not be used as a local anesthetic.

Antihistamines are also Contraindicated in the Following Conditions

Hypersensitivity to diphenhydramine hydrochloride and other antihistamines of similar chemical structure.

Adverse Reactions

The most frequent adverse reactions are italicized.

General

Urticaria; drug rash; anaphylactic shock; photosensitivity; excessive perspiration; chills; dryness of mouth, nose and throat.

Cardiovascular System

Hypotension, headache, palpitations, tachycardia, extrasystoles.

Hematologic System

Hemolytic anemia, thrombocytopenia, agranulocytosis.

Nervous System

Sedation, sleepiness, dizziness, disturbed coordination, fatigue, confusion, restlessness, excitation, nervousness, tremor, irritability, insomnia, euphoria, paresthesia, blurred vision, diplopia, vertigo, tinnitus, acute labyrinthitis, neuritis, convulsions.

Gastrointestinal System

Epigastric distress, anorexia, nausea, vomiting, diarrhea, constipation.

Genitourinary System

Urinary frequency, difficult urination, urinary retention, early menses.

Respiratory System

Thickening of bronchial secretions, tightness of chest and wheezing, nasal stuffiness.

Drug Interactions

Diphenhydramine hydrochloride has additive effects with alcohol and other CNS depressants (hypnotics, sedatives, tranquilizers, etc.)

MAO inhibitors prolong and intensify the anticholinergic (drying) effects of antihistamines.

How Supplied

Diphenhydramine Hydrochloride Injection, USP 50 mg/mL is a sterile, nonpyrogenic, clear colourless solution, and is supplied as 1 mL single dose vial in package of 25s

NDC: 70518-4536-00

NDC: 70518-4536-01

PACKAGING: 25 in 1 PACKAGE

PACKAGING: 1 mL in 1 VIAL,GLASS Type 0

Storage

Discard unused portion

Protect from light. Keep covered in carton until time of use. Store at 20° to 25°C (68° to 77°F); excursions permitted between 15° to 30°C (59° to 86°F) [See USP Controlled Room Temperature].

To report SUSPECTED ADVERSE REACTIONS, contact Avet Pharmaceuticals Inc. at 1-866-901-DRUG (3784), or the FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

Repackaged and Distributed By:

Remedy Repack, Inc.

625 Kolter Dr. Suite #4 Indiana, PA 1-724-465-8762

Description

Diphenhydramine Hydrochloride Injection, USP  is a sterile, nonpyrogenic solution for intravenous or deep intramuscular use as an antihistaminic agent. Each mL contains diphenhydramine hydrochloride 50 mg in Water for Injection. pH 4.0 to 6.5; sodium hydroxide and/or hydrochloric acid added, if needed, for pH adjustment. The chemical name of diphenhydramine hydrochloride is 2-(Diphenylmethoxy)-N,N-dimethylethylamine hydrochloride.

The structural formula is as follows:

C 17H 21NO • HCl MW 291.82

Diphenhydramine hydrochloride occurs as a white crystalline powder and is freely soluble in water and alcohol.

Section 51945-4

DRUG: Diphenhydramine Hydrochloride

GENERIC: Diphenhydramine Hydrochloride

DOSAGE: INJECTION

ADMINSTRATION: INTRAMUSCULAR

NDC: 70518-4536-0

NDC: 70518-4536-1

PACKAGING: 1 mL in 1 VIAL, GLASS

OUTER PACKAGING: 25 in 1 PACKAGE

ACTIVE INGREDIENT(S):

  • DIPHENHYDRAMINE HYDROCHLORIDE 50mg in 1mL

INACTIVE INGREDIENT(S):

  • WATER
  • SODIUM HYDROXIDE
  • HYDROCHLORIC ACID

General

Diphenhydramine hydrochloride has an atropine-like action and, therefore, should be used with caution in patients with a history of bronchial asthma, increased intraocular pressure, hyperthyroidism, cardiovascular disease or hypertension. Use with caution in patients with lower respiratory disease, including asthma.

Warnings

Antihistamines should be used with considerable caution in patients with narrow-angle glaucoma, stenosing peptic ulcer, pyloroduodenal obstruction, symptomatic prostatic hypertrophy or bladder-neck obstruction.

Local necrosis has been associated with the use of subcutaneous or intradermal use of intravenous diphenhydramine.

Use in Pediatric Patients

In pediatric patients, especially, antihistamines in overdosagemay cause hallucinations, convulsions or death.

As in adults, antihistamines may diminish mental alertness in pediatric patients. In the young pediatric patient, particularly, they may produce excitation.

Use in the Elderly (approximately 60 years or older)

Antihistamines are more likely to cause dizziness, sedation and hypotension in elderly patients.

Pregnancy

Teratogenic Effects

Reproduction studies have been performed in rats and rabbits at doses up to 5 times the human dose and have revealed no evidence of impaired fertility or harm to the fetus due to diphenhydramine hydrochloride. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.

Overdosage

Antihistamine overdosage reactions may vary from central nervous system depression to stimulation. Stimulation is particularly likely in pediatric patients. Atropine-like signs and symptoms, dry mouth; fixed, dilated pupils; flushing, and gastrointestinal symptoms may also occur.

Stimulantsshould notbe used.

Vasopressors may be used to treat hypotension.

Pediatric Use

Diphenhydramine should not be used in neonates and premature infants (see CONTRAINDICATIONS ). 

Diphenhydramine may diminish mental alertness, or in the young pediatric patient, cause excitation. Overdosage may cause hallucinations, convulsions or death (see WARNINGS and OVERDOSAGE ). 

See also DOSAGE AND ADMINISTRATION section.

Clinical Pharmacology

Diphenhydramine hydrochloride is an antihistamine with anticholinergic (drying) and sedative side effects. Antihistamines appear to compete with histamine for cell receptor sites on effector cells.

Diphenhydramine hydrochloride in the injectable form has a rapid onset of action. Diphenhydramine is widely distributed throughout the body, including the CNS. A portion of the drug is excreted unchanged in the urine, while the rest is metabolized via the liver. Detailed information on the pharmacokinetics of diphenhydramine hydrochloride injection, USP is not available.

Information for Patients

Patients taking diphenhydramine hydrochloride should be advised that this drug may cause drowsiness and has an additive effect with alcohol.

Patients should be warned about engaging in activities requiring mental alertness, such as driving a car or operating appliances, machinery, etc.

Repackaged By / Distributed By: RemedyRepack Inc.

625 Kolter Drive, Indiana, PA 15701

(724) 465-8762

Carcinogenesis, Mutagenesis, Impairment of Fertility

Long-term studies in animals to determine mutagenic and carcinogenic potential have not been performed.


Structured Label Content

Section 51945-4 (51945-4)

DRUG: Diphenhydramine Hydrochloride

GENERIC: Diphenhydramine Hydrochloride

DOSAGE: INJECTION

ADMINSTRATION: INTRAMUSCULAR

NDC: 70518-4536-0

NDC: 70518-4536-1

PACKAGING: 1 mL in 1 VIAL, GLASS

OUTER PACKAGING: 25 in 1 PACKAGE

ACTIVE INGREDIENT(S):

  • DIPHENHYDRAMINE HYDROCHLORIDE 50mg in 1mL

INACTIVE INGREDIENT(S):

  • WATER
  • SODIUM HYDROXIDE
  • HYDROCHLORIC ACID

General

Diphenhydramine hydrochloride has an atropine-like action and, therefore, should be used with caution in patients with a history of bronchial asthma, increased intraocular pressure, hyperthyroidism, cardiovascular disease or hypertension. Use with caution in patients with lower respiratory disease, including asthma.

Warnings (WARNINGS)

Antihistamines should be used with considerable caution in patients with narrow-angle glaucoma, stenosing peptic ulcer, pyloroduodenal obstruction, symptomatic prostatic hypertrophy or bladder-neck obstruction.

Local necrosis has been associated with the use of subcutaneous or intradermal use of intravenous diphenhydramine.

Use in Pediatric Patients

In pediatric patients, especially, antihistamines in overdosagemay cause hallucinations, convulsions or death.

As in adults, antihistamines may diminish mental alertness in pediatric patients. In the young pediatric patient, particularly, they may produce excitation.

Use in the Elderly (approximately 60 years or older)

Antihistamines are more likely to cause dizziness, sedation and hypotension in elderly patients.

Pregnancy

Teratogenic Effects

Reproduction studies have been performed in rats and rabbits at doses up to 5 times the human dose and have revealed no evidence of impaired fertility or harm to the fetus due to diphenhydramine hydrochloride. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.

Overdosage (OVERDOSAGE)

Antihistamine overdosage reactions may vary from central nervous system depression to stimulation. Stimulation is particularly likely in pediatric patients. Atropine-like signs and symptoms, dry mouth; fixed, dilated pupils; flushing, and gastrointestinal symptoms may also occur.

Stimulantsshould notbe used.

Vasopressors may be used to treat hypotension.

Description (DESCRIPTION)

Diphenhydramine Hydrochloride Injection, USP  is a sterile, nonpyrogenic solution for intravenous or deep intramuscular use as an antihistaminic agent. Each mL contains diphenhydramine hydrochloride 50 mg in Water for Injection. pH 4.0 to 6.5; sodium hydroxide and/or hydrochloric acid added, if needed, for pH adjustment. The chemical name of diphenhydramine hydrochloride is 2-(Diphenylmethoxy)-N,N-dimethylethylamine hydrochloride.

The structural formula is as follows:

C 17H 21NO • HCl MW 291.82

Diphenhydramine hydrochloride occurs as a white crystalline powder and is freely soluble in water and alcohol.

How Supplied (HOW SUPPLIED)

Diphenhydramine Hydrochloride Injection, USP 50 mg/mL is a sterile, nonpyrogenic, clear colourless solution, and is supplied as 1 mL single dose vial in package of 25s

NDC: 70518-4536-00

NDC: 70518-4536-01

PACKAGING: 25 in 1 PACKAGE

PACKAGING: 1 mL in 1 VIAL,GLASS Type 0

Storage

Discard unused portion

Protect from light. Keep covered in carton until time of use. Store at 20° to 25°C (68° to 77°F); excursions permitted between 15° to 30°C (59° to 86°F) [See USP Controlled Room Temperature].

To report SUSPECTED ADVERSE REACTIONS, contact Avet Pharmaceuticals Inc. at 1-866-901-DRUG (3784), or the FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

Repackaged and Distributed By:

Remedy Repack, Inc.

625 Kolter Dr. Suite #4 Indiana, PA 1-724-465-8762

Pediatric Use

Diphenhydramine should not be used in neonates and premature infants (see CONTRAINDICATIONS ). 

Diphenhydramine may diminish mental alertness, or in the young pediatric patient, cause excitation. Overdosage may cause hallucinations, convulsions or death (see WARNINGS and OVERDOSAGE ). 

See also DOSAGE AND ADMINISTRATION section.

Adverse Reactions (ADVERSE REACTIONS)

The most frequent adverse reactions are italicized.

General

Urticaria; drug rash; anaphylactic shock; photosensitivity; excessive perspiration; chills; dryness of mouth, nose and throat.

Cardiovascular System

Hypotension, headache, palpitations, tachycardia, extrasystoles.

Hematologic System

Hemolytic anemia, thrombocytopenia, agranulocytosis.

Nervous System

Sedation, sleepiness, dizziness, disturbed coordination, fatigue, confusion, restlessness, excitation, nervousness, tremor, irritability, insomnia, euphoria, paresthesia, blurred vision, diplopia, vertigo, tinnitus, acute labyrinthitis, neuritis, convulsions.

Gastrointestinal System

Epigastric distress, anorexia, nausea, vomiting, diarrhea, constipation.

Genitourinary System

Urinary frequency, difficult urination, urinary retention, early menses.

Respiratory System

Thickening of bronchial secretions, tightness of chest and wheezing, nasal stuffiness.

Contraindications (CONTRAINDICATIONS)

Use in Neonates or Premature Infants

This drug should not be used in neonates or premature infants.

Use in Nursing Mothers

Because of the higher risk of antihistamines for infants generally, and for neonates and prematures in particular, antihistamine therapy is contraindicated in nursing mothers.

Use as a Local Anesthetic

Because of the risk of local necrosis, this drug should not be used as a local anesthetic.

Antihistamines are also Contraindicated in the Following Conditions

Hypersensitivity to diphenhydramine hydrochloride and other antihistamines of similar chemical structure.

Drug Interactions

Diphenhydramine hydrochloride has additive effects with alcohol and other CNS depressants (hypnotics, sedatives, tranquilizers, etc.)

MAO inhibitors prolong and intensify the anticholinergic (drying) effects of antihistamines.

Clinical Pharmacology (CLINICAL PHARMACOLOGY)

Diphenhydramine hydrochloride is an antihistamine with anticholinergic (drying) and sedative side effects. Antihistamines appear to compete with histamine for cell receptor sites on effector cells.

Diphenhydramine hydrochloride in the injectable form has a rapid onset of action. Diphenhydramine is widely distributed throughout the body, including the CNS. A portion of the drug is excreted unchanged in the urine, while the rest is metabolized via the liver. Detailed information on the pharmacokinetics of diphenhydramine hydrochloride injection, USP is not available.

Indications and Usage (INDICATIONS AND USAGE)

Diphenhydramine hydrochloride injection, USP is effective in adults and pediatric patients, other than premature infants and neonates, for the following conditions when the oral form is impractical.

Antihistaminic

For amelioration of allergic reactions to blood or plasma, in anaphylaxis as an adjunct to epinephrine and other standard measures after the acute symptoms have been controlled and for other uncomplicated allergic conditions of the immediate type when oral therapy is impossible or contraindicated.

Motion Sickness

For active treatment of motion sickness.

Antiparkinsonism

For use in parkinsonism, when oral therapy is impossible or contraindicated, as follows: parkinsonism in the elderly who are unable to tolerate more potent agents, mild cases of parkinsonism in other age groups and in other cases of parkinsonism in combination with centrally acting anticholinergic agents.

Information for Patients

Patients taking diphenhydramine hydrochloride should be advised that this drug may cause drowsiness and has an additive effect with alcohol.

Patients should be warned about engaging in activities requiring mental alertness, such as driving a car or operating appliances, machinery, etc.

Repackaged By / Distributed By: RemedyRepack Inc.

625 Kolter Drive, Indiana, PA 15701

(724) 465-8762

Dosage and Administration (DOSAGE AND ADMINISTRATION)

THIS PRODUCT IS FOR INTRAVENOUS OR INTRAMUSCULAR ADMINISTRATION ONLY.

Diphenhydramine hydrochloride injection, USP is indicated when the oral form is impractical.

DOSAGE SHOULD BE INDIVIDUALIZED ACCORDING TO THE NEEDS AND THE RESPONSE OF THE PATIENT.

Pediatric Patients, Other Than Premature Infants and Neonates

5 mg/kg/24 hours or 150 mg/m 2/24 hours. Maximum daily dosage is 300 mg. Divide into four doses, administered intravenously at a rate generally not exceeding 25 mg/min, or deep intramuscularly.

Adults

10 mg to 50 mg intravenously at a rate generally not exceeding 25 mg/min, or deep intramuscularly; 100 mg if required; maximum daily dosage is 400 mg.

Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.

Carcinogenesis, Mutagenesis, Impairment of Fertility

Long-term studies in animals to determine mutagenic and carcinogenic potential have not been performed.


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