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Allergic Rhinitis and Antihistamines

Read more about Antihistamines.


Antihistamines are a common treatment for allergic conditions such as allergic rhinitis. They come in prescription and over-the-counter forms.

The following antihistamines are available over-the-counter, without a prescription. Many of these are older (first-generation) antihistamines. (Note: First-generation antihistamines can cause drowsiness.)

  • Diphenhydramine (Benadryl)
  • Chlorpheniramine (Chlor-Trimeton)
  • Brompheniramine (Dimetane)
  • Dexbrompheniramine and pseudoephedrine (Drixoral)
  • Clemastine (Tavist)
  • Chlorpheniramine and phenylpropanolamine (Triaminic Allergy)

Several second-generation antihistamines are also available over the counter. (Note: Second-generation antihistamines are non-sedating.)

  • Loratadine (Claritin)
  • Cetirizine hydrochloride (Zyrtec)

Common prescription antihistamines include:

  • Fexofenadine (Allegra)
  • Desloratadine (Clarinex)
  • Levocetirizine (Xyzal)

Nasal antihistamine sprays are also available, such as azelastine (Astelin).

Effect of Antihistamines on Allergic Rhinitis

Antihistamines help reduce or block the action of histamine, a chemical that is released when the immune system reacts to an allergen. The release of histamine leads to the symptoms of allergic rhinitis.

Side Effects and Warnings

Possible side effects of over-the-counter antihistamines include:

  • Drowsiness (Claritin and Zyrtec are non-sedating)
  • Slowed reaction time
  • Dry mouth

Possible side effects of prescription antihistamines include:

  • Drowsiness
  • Lightheadness
  • Blurry vision
  • Change in ability to think clearly
  • Dry mouth, nose, or throat
  • Gastrointestinal upset, stomach pain, or nausea
  • Increased appetite and weight gain
  • Thickening of mucus
  • Increased effects in people with kidney disease due to slower removal from the body


Effect of Decongestants on Allergic Rhinitis

Read more about Allergic Rhinitis and Decongestants.