No, that is marketing information on the label. There are not different “forms” of the same antihistamines. For example, there is a group of common antihistamines that work for 18 - 24 hours. They are also called “second-generation” antihistamines. Common ones are:
- Zyrtec (Cetirizine)
- Allegra (Fexofenadine)
- Claritin (Loratadine)
There aren’t different “forms” of these medications with different “lengths of action.” These drugs are different from Benadryl (Diphenhydramine) that works for four to six hours. Compared to Benadryl, second-generation antihistamines have fewer side effects (e.g., drowsiness).
Finally, antihistamines help control rashes and itching due to hives. They help with common allergy symptoms. This includes itching, sneezing, and runny nose, among others.