First-generation antihistamines

Definition

First-generation antihistamines are medications that block histamine H1 receptors to alleviate allergic symptoms. They often cause sedation due to their ability to cross the blood-brain barrier.

5 Must Know Facts For Your Next Test

1. First-generation antihistamines can cause drowsiness and impair cognitive functions due to central nervous system penetration.
2. These drugs are commonly used for treating allergic rhinitis, urticaria, and motion sickness.
3. They have a shorter duration of action compared to second-generation antihistamines, typically requiring multiple doses per day.
4. Common first-generation antihistamines include diphenhydramine, chlorpheniramine, and promethazine.
5. Due to their sedative effects, they are sometimes used as nighttime sleep aids.

Review Questions

• What is a primary side effect of first-generation antihistamines that impacts daily activities?
• Name three conditions that first-generation antihistamines are commonly used to treat.
• Why do first-generation antihistamines often require multiple doses per day?

Related terms

Second-Generation Antihistamines: Medications that block histamine H1 receptors but do not significantly cross the blood-brain barrier, causing less sedation.

Decongestants: Medications that reduce nasal congestion by constricting blood vessels in the nasal passages.

Cerumenolytics: Agents used to soften and break down earwax for easier removal from the ear canal.