Antihistamine brand and generic names (H1)
One table for first- and second-generation H1 antihistamines. The route/availability column summarizes generation and typical OTC versus Rx labeling.
H1 antihistamine brand and generic names
| Brand name | Generic name | Class or type | Route / form |
|---|---|---|---|
| Benadryl (oral allergy products) | diphenhydramine | Antihistamines | First gen · OTC (oral) |
| Atarax / Vistaril | hydroxyzine | Antihistamines | First gen · Rx |
| Chlor-Trimeton | chlorpheniramine | Antihistamines | First gen · OTC |
| Phenergan | promethazine | Antihistamines | First gen · Rx |
| Unisom SleepTabs | doxylamine | Antihistamines | First gen · OTC |
| Zyrtec | cetirizine | Antihistamines | Second gen · OTC / Rx |
| Claritin | loratadine | Antihistamines | Second gen · OTC |
| Clarinex | desloratadine | Antihistamines | Second gen · Rx |
| Xyzal | levocetirizine | Antihistamines | Second gen · OTC / Rx |
| Allegra | fexofenadine | Antihistamines | Second gen · OTC / Rx |
| Astepro | azelastine | Antihistamines | Second gen · intranasal · Rx |
| Astepro | azelastine | Antihistamines | Second gen · intranasal · OTC / Rx |
H2 blockers are not H1 antihistamines
H2 receptor antagonists (H2 blockers) reduce stomach acid. They are sometimes called “antihistamines” in broad language but belong in acid-suppression study sets with proton pump inhibitors.
See the H2 blocker brand and generic names guide and the PPI brand names guide for famotidine, cimetidine, historical ranitidine, omeprazole, and related pairs.
Understanding antihistamines
First-generation H1 antihistamines such as diphenhydramine and hydroxyzine cross the blood–brain barrier more readily and tend to cause more sedation. Second-generation oral agents such as cetirizine, loratadine, and fexofenadine are often preferred for daytime allergy symptoms.
Intranasal azelastine (Astelin, Astepro) is an H1 antihistamine with a nasal route—route is part of the product identity. Flonase (fluticasone) is a corticosteroid, not an antihistamine.
Naming patterns and memory tips
Pair cetirizine (Zyrtec) with levocetirizine (Xyzal) and loratadine (Claritin) with desloratadine (Clarinex) as related but distinct generics.
Claritin-D adds pseudoephedrine; the D marks a decongestant combination, not a second antihistamine.
Commonly confused antihistamine names
Zyrtec and Xyzal
Levocetirizine is the active enantiomer related to cetirizine; keep both brand pairs separate in mixed review.
Hydroxyzine and hydralazine
Hydroxyzine is an antihistamine; hydralazine is a vasodilator used in hypertension.
Famotidine and fexofenadine
Pepcid–famotidine is an H2 blocker; Allegra–fexofenadine is an H1 antihistamine.