Definition

Noun: * A type of medication used to treat symptoms caused by an excess of histamine in the body, such as those from allergies, hay fever, and the common cold. It works by blocking histamine from binding to its receptor sites, thereby counteracting its effects.

Usage

Antihistamines are primarily used to relieve symptoms like sneezing, itching, watery eyes, and runny nose. They are available over-the-counter and by prescription, and can be sedating or non-sedating.

Examples

• "I took an antihistamine to stop my eyes from itching."
• "For severe seasonal allergies, her doctor prescribed a stronger antihistamine."
• "Some antihistamines can cause drowsiness, so it's important to read the label."

Advanced Usage

• First-generation vs. second-generation antihistamines: This distinction is common in medical contexts. First-generation types (e.g., diphenhydramine) often cause sedation, while second-generation types (e.g., loratadine, cetirizine) are typically non-sedating.
• H1-receptor antagonist: This is the technical pharmacological term for most common antihistamines, specifying that they block the H1 type of histamine receptor.

Variants and Related Words

• Antihistaminic (adjective): Having the effect of an antihistamine.
  • "The drug's antihistaminic properties provide relief from hives."

Synonyms

• Histamine blocker
• Allergy medication (Note: This is a broader category that includes antihistamines.)

Related Phrases

• Take an antihistamine: The standard phrase for using this medicine.
  • "You should take an antihistamine before visiting a house with cats if you're allergic."
• Antihistamine eye drops/nasal spray: Specific formulations of the medication for targeted relief.

Noun

1. a medicine used to treat allergies and hypersensitive reactions and colds; works by counteracting the effects of histamine on a receptor site