Diphenhydramine

Question 1

Diphenhydramine Class

Answer 1

H1 antihistamine (B)

Question 2

Diphenhydramine Indications

Answer 2

Mild to moderate allergic reactions, anaphylaxis (give after administering epinephrine), dystonic reactions, and other extrapyramidal symptoms

Question 3

Diphenhydramine Mechanism

Answer 3

blocks histamines at H1 receptor sites, reverses dystonic reactions and extrapyramidal symptoms

Question 4

Diphenhydramine Side Effects

Answer 4

1. dizziness
2. Drowsiness
3. Confusion
4. Dilated pupil
5. Dry mouth
6. Headache
7. Mucus plugs
8. Nausea
9. Palpitations
10. Seizures
11. Tachycardia
12. Wheezing
13. Vomiting

Question 5

Diphenhydramine Contraindications

Answer 5

hypersensitivity, neonates, preterm infants, late-stage pregnancy or lactation

Question 6

Diphenhydramine Precautions

Answer 6

use caution in the elderly and patients with heart disease, hypertension, asthma, or COPD (may precipitate an acute asthma attack due to thickening of mucosal secretions), glaucoma (may increase intraocular pressure)

Question 7

Diphenhydramine Interactions

Answer 7

use with alcohol, sedatives, or other CNS depressants may have an additive effect

Question 8

Diphenhydramine Routes of Administration

Answer 8

slow IVP, IO, deep IM, PO

Question 9

Diphenhydramine Onset

Answer 9

15–30 minutes

Question 10

Diphenhydramine Duration

Answer 10

3–12 hours

Question 11

Diphenhydramine Dose Adult

Answer 11

25–50 mg IV at 25 mg/min, repeated PRN

Question 12

Diphenhydramine Dose Pedi

Answer 12

1–2 mg/kg IV (IM not recommended)