First-generation antihistamine

First-generation antihistamines are a class of medications that were first developed in the mid-20th century for the treatment of allergies. They work by blocking the action of histamine, a chemical in the body that triggers allergic reactions.

History

The first antihistamines were developed in the 1930s and 1940s, following the discovery of histamine in the body and its role in allergic reactions. These early medications, such as diphenhydramine and chlorpheniramine, are known as first-generation antihistamines.

Mechanism of action

First-generation antihistamines work by blocking the action of histamine at the H1 receptor. Histamine is a chemical in the body that triggers symptoms of allergies, such as sneezing, itching, and runny nose. By blocking the action of histamine, these medications can reduce these symptoms.

Uses

First-generation antihistamines are used to treat a variety of conditions, including allergic rhinitis, urticaria (hives), and atopic dermatitis. They are also used to treat symptoms of the common cold and to aid in sleep, as they have sedative effects.

Side effects

The most common side effects of first-generation antihistamines include drowsiness, dry mouth, and blurred vision. These medications can also cause confusion and memory problems in older adults.

Examples

Examples of first-generation antihistamines include diphenhydramine (Benadryl), chlorpheniramine (Chlor-Trimeton), and hydroxyzine (Atarax).

See also

• Second-generation antihistamines
• Histamine H1 receptor
• Allergic reaction