Diphenhydramine

(Benedryl)

Classification:         

Action:                   

Competes with histamines at receptor sites

Reverses dystonic reactions

Indications:            

Allergic reaction 

Adjunct to epinephrine in treating

anaphylaxis

Dystonic reactions

Contraindications: 

Glaucoma

Acute asthma

Lactating mother

Adverse Effects:     

Cardiovascular           

hypotension

palpitations  

bradycardia

Neurological  

drowsiness                                                                             dizziness

headache  

dilated pupils 

seizures

Respiratory             

wheezing                                                      

mucus plugs   

Gastrointestinal

dry mouth

nausea/vomit                                                               

Administration:       

50-100 mg slow IV/IO at 25mg/minute or deep IM

Pediatrics:               

1mg/kg slow IV/IO over several minutes

Onset:      

Duration:                   

              Onset:   IV   1-5 minutes  IM  10-15 minutes

                      Duration:        3-4 hours

Note:  

May precipitate acute asthma due to drying effect on bronchial mucosa and thickening of secretions.

May increase ocular pressure in glaucoma due to atropine like effect.