Which hay fever symptoms can H1 antihistamines help relieve?

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antihistamines, including Benadryl — antihistamine Antihistamines such as Benadryl (diphenhydramine) and Claritin (loratadine) can be purchased without prescriptions. Both of those agents act by blocking H₁ receptors. However, whereas Benadryl binds to those receptors in the central nervous system (CNS), causing drowsiness, Claritin does not readily enter the CNS and thus does not normally cause drowsiness.

H1 antihistamines are effective in treating seasonal hay fever—which includes seasonal rhinitis and conjunctivitis—by competing with histamine for H1 receptor sites.1

These drugs help relieve the following symptoms associated with hay fever:
* Sneezing1
* Rhinorrhea (runny nose)1
* Itching of the eyes, nose, and throat1

H1 antihistamines are generally most successful when used at the beginning of the hay-fever season, when allergen concentrations are lower.1