DIPHENHYDRAMINE

DIPHENHYDRAMINE

Diphenhydramine belongs to the ethanolamine class of antihistamines.

Mechanism of action

• Diphenhydramine antagonizes the effects of histamine on H_{A} -receptors, leading to a reduction of the negative symptoms brought on by histamine HA-receptor binding.

Indication

• Alleviation of allergy symptoms
• To avoid motion sickness
• Treatment of dystonic responses brought on by phenothiazine
• Meniere's illness and vertigo
• Vomiting, nausea, and motion sickness
• Insect sting
• An aid to sleep at night

Dose

Adult

• 25 to 50 mg orally, twice daily.
• IM/IV: 10–50 mg per dose

Child 

• 12.5–25 mg tid–qid.
• 5 mg/kg/day, ay.

Contraindication

• Neonates, lactation, narrow-angle glaucoma, prostatic hypertrophy, bladder neck obstruction, gastrointestinal obstruction or stenosis, acute asthma attacks,

Side effect

Hypotension, palpitations, urinary retention, CNS depression, sedation, drowsiness, restlessness, confusion, depression, agitation, and euphoria, as well as GI disturbances like nausea and vomiting, dry mouth, thickened respiratory secretions, blurred vision, weakness, tachycardia, hypotension, and hypertension, as well as cardiovascular collapse. Hepatic dysfunction and paradoxical excitation.

Nursing consideration

• Give alongside food or milk to reduce GI side effects.
• Avoid potentially dangerous activities while driving.
• Use with caution around preterm or term newborns.
• Avoid breastfeeding while using this medication.