H1 antihistamines
- Block/inversely agonize H1 receptors
- Treat allergy, itch + urticaria
- 1st-gen drugs cross BBB and sedate
- 2nd-gen drugs are usually less sedating
- Some 1st-gen drugs are antimuscarinic
- Not adequate treatment for anaphylactic shock
Class at a glance
- Block/inversely agonize H1 receptors
Clinical role
- Treat allergy, itch + urticaria
Other clinical roles
- Some 1st-gen drugs are antimuscarinic
- Not adequate treatment for anaphylactic shock
Safety / monitoring
- 1st-gen drugs cross BBB and sedate
- 2nd-gen drugs are usually less sedating
Self-check
- Why do first-generation H1 antihistamines sedate?
They cross the BBB. - Are H1 antihistamines adequate treatment for anaphylactic shock?
No.
Drugs in this class (16)
H1 antihistamines prescription history
Animated chart of estimated U.S. prescriptions per year, H1 antihistamines (1944–2026).
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