Antihistamines

action:
blocks histamine at receptor sites
examples
1. promethazine HCL (Phenergan)
2. chlorpheniramine maleate (Chlor-Trimeton)
3. diphenhydramine (Benedryl)
uses
1. relieves symptoms of allergies, colds, pruritus
2. prevents problems in blood transfusion and drug reactions
adverse effects
1. drowsiness
2. gastric effects
3. dry mouth
4. headache
5. thickening of bronchial secretions
contraindications
1. acute asthma
2. lower respiratory heart disease
3. narrow angle glaucoma
nursing interventions
1. discontinue four days before skin testing for allergies
2. avoid interaction with CNS depressants
3. teach client
* avoid driving and hazardous activities
* take antihistamines with food
* additive effect with alcohol, other CNS depressants