Label: DIPHENHYDRAMINE- diphenhydramine hydrochloride injection, solution
- NDC Code(s): 83634-781-01, 83634-781-41
- Packager: Avenacy, LLC
- Category: HUMAN PRESCRIPTION DRUG LABEL
- DEA Schedule: None
- Marketing Status: Abbreviated New Drug Application
Drug Label Information
Updated May 16, 2025
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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:
Diphenhydramine hydrochloride occurs as a white crystalline powder and is freely soluble in water and alcohol.
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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.
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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.
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.
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CONTRAINDICATIONS
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.
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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.
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PRECAUTIONS
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.
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.
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.
Carcinogenesis, Mutagenesis, Impairment of Fertility
Long-term studies in animals to determine mutagenic and carcinogenic potential have not been performed.
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.
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.
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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.
To report SUSPECTED ADVERSE REACTIONS, contact Avenacy at 1-855-283-6229 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
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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.
Stimulants should not be used.
Vasopressors may be used to treat hypotension.
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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/m2/24 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.
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HOW SUPPLIED
Diphenhydramine Hydrochloride Injection, USP 50 mg per mL is a clear, colorless solution supplied as follows:
NDC Diphenhydramine Hydrochloride Injection, USP Package Factor 83634-781-01 50 mg per mL Single-Dose Vial 25 vials per carton Storage Conditions
Store at 20° to 25°C (68° to 77°F); excursions permitted between 15° and 30°C (59° and 86°F). [See USP Controlled Room Temperature.]
Protect from light. Keep covered in carton until time of use.
Discard unused portion.
Sterile, Nonpyrogenic, Preservative-free.
The container closure is not made with natural rubber latex.AVENACY
Mfd. for Avenacy
Schaumburg, IL 60173 (USA)
Made in India
©2025 AvenacyRevised: May 2025
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INGREDIENTS AND APPEARANCE
DIPHENHYDRAMINE
diphenhydramine hydrochloride injection, solutionProduct Information Product Type HUMAN PRESCRIPTION DRUG Item Code (Source) NDC:83634-781 Route of Administration INTRAVENOUS, INTRAMUSCULAR Active Ingredient/Active Moiety Ingredient Name Basis of Strength Strength diphenhydramine hydrochloride (UNII: TC2D6JAD40) (diphenhydramine - UNII:8GTS82S83M) diphenhydramine hydrochloride 50 mg in 1 mL Inactive Ingredients Ingredient Name Strength SODIUM HYDROXIDE (UNII: 55X04QC32I) HYDROCHLORIC ACID (UNII: QTT17582CB) Packaging # Item Code Package Description Marketing Start Date Marketing End Date 1 NDC:83634-781-01 25 in 1 CARTON 09/01/2025 1 NDC:83634-781-41 1 mL in 1 VIAL, SINGLE-DOSE; Type 0: Not a Combination Product Marketing Information Marketing Category Application Number or Monograph Citation Marketing Start Date Marketing End Date ANDA ANDA205336 09/01/2025 Labeler - Avenacy, LLC (119060628)
