Diphenhydramine | Drug Overview & Clinical Reference
Diphenhydramine
Clinical safety rating: caution
Animal studies have demonstrated safety
How it works
Mechanism information is still being processed. Check the DailyMed link in the sidebar for the official prescribing information.
Dosing & administration
Dosing varies by indication and patient profile. Always follow your institution's current prescribing guidelines.
Renal impairment
Consult protocols for adjustment.
Liver impairment
Consult protocols for adjustment.
Use during pregnancy
1st trimester
Safe. No established teratogenic risk.
2nd trimester
Safe, though second-generation antihistamines preferred.
3rd trimester
Caution within 2 weeks of delivery. Can cause neonatal CNS depression, jitteriness, and feeding difficulties. Avoid high doses near delivery.
Clinical note
First-generation sedating antihistamine used for allergic conditions, sleep, and NVP. More sedating than second-generation agents. No established teratogenicity in humans but limited near-term use recommended. When used very close to delivery, associated with neonatal CNS depression, jitteriness, and respiratory issues. Prefer second-generation antihistamines (cetirizine, loratadine) for routine use.
Breastfeeding
Caution. Sedation in infant possible; may suppress lactation. Prefer alternatives for breastfeeding mothers.
