What is an antihistamine?

Antihistamines are medicines that treat mild allergic reactions. Antihistamines come in tablets and liquids. They work by stopping histamine.

Antihistamines work by counteracting histamines, thus reducing the inflammation and irritation caused by histamines. They tend to do the trick, but can have side effects, such as dry nasal cavities, drowsiness and other undesirable conditions.

Antihistamines are medications that block histamine, a substance released by the body in response to allergens.

Some oral antihistamines, such as diphenhydramine, can cause drowsiness and may be best when taken at night. Daytime antihistamine options include:

  • loratadine (Claritin)
  • fexofenadine (Allegra)
  • cetirizine (Zyrtec)

Antihistamines in the form of a nasal spray are only available by prescription and typically are used to treat more severe allergy symptoms. Nasal antihistamines directly target the nasal passages, but may cause a bitter taste and/or headache.

An antihistamine is a type of medication. It lessens the effects of compounds released by the body during an allergic reaction.

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