一代抗組織胺 Allergic rhinitis, Anaphylaxis (Adjunct), Common cold, Insomnia, Motion sickness, Parkinsonism, Pruritus of skin

First generation Histamine H₁ Antagonist
DiphenhydrAMINE hydrochloride acts as an antihistamine by competing with histamine for receptor sites on effector cells.

Vd: widely distributed
Metabolism: Hepatic
Excretion: Renal

1. Hypersensitivity to diphenhydrAMINE and other similar antihistamines
2. Newborns or premature infants
3. Nursing mothers
4. Use as a local anesthetic

B (FDA) A(AUS)

Infant risk cannot be ruled out (MDX)

Xerostomia, Dizziness, Dyskinesia, Sedated, Somnolence, Nasal mucosa dry, Pharyngeal dryness, Thick sputum, Bronchial, Anaphylaxis

Allergic rhinitis:
10 to 50 mg IM/IV every 2 to 3 h; maximum parenteral dose: 400 mg/day
Anaphylaxis; Adjunct:
10 to 50 mg IM/IV (rate not to exceed 25 mg/min) every 2 to 3 h; doses of 100 mg/dose may be used if necessary; maximum parenteral dose: 400 mg/day
Motion sickness:
10 to 50 mg IV/IM (rate not to exceed 25 mg/min); doses up to 100 mg/dose may be used if necessary; MAX dose: 400 mg/day
Parkinsonism:
10 to 50 mg IV/IM (rate not to exceed 25 mg/min); doses up to 100 mg/dose may be used if necessary; MAX dose: 400 mg/day
Pruritus of skin:
apply to affected area not more than 3 to 4 times daily

Not recommended in infants or neonates
Allergic rhinitis:
5 mg/kg/day or 150 mg/m²/day IM/IV divided in 4 doses, MAX 300 mg/day
Anaphylaxis; Adjunct:
in addition to epinephrine therapy, 5 mg/kg/day or 150 mg/m²/day IM/IV (rate not to exceed 25 mg/min) divided in 4 doses, MAX 300 mg/day
Motion sickness:
5 mg/kg/day or 150 mg/m²/day divided into 4 doses (rate not to exceed 25 mg/min); MAX dose: 300 mg/day
Pruritus of skin:
apply to affected area not more than 3 to 4 times daily

1. Mild impairment (eGFR >50 mL/min): increase dosing interval to every 6 hours
2. Moderate impairment (eGFR 10-50 mL/min): increase dosing interval to every 6-12 hours
3. Severe impairment (eGFR <10 mL/min): increase dosing interval to every 12-18 hours