Some customers will prefer to use one product to treat all of their hayfever symptoms. Antihistamine tablets and syrups work by blocking the action of histamine, which is one of the chemicals released when a susceptible person encounters pollen. These products tend to start working quickly and they relieve most allergy symptoms. They can be taken as and when sufferers notice symptoms or on a daily basis as a preventative treatment.

Oral antihistamines are separated into two groups:

Older compounds €“ the most common example is chlorphenamine (e.g. Piriton Allergy Tablets). This is a relatively non-specific antihistamine and one of its drawbacks is that it can cause drowsiness. Older antihistamines have a shorter duration of action and so need to be taken more frequently (e.g. every four to six hours). However, these products are often more affordable, which can make them more appealing to some customers. 

Newer compounds €“ examples include acrivastine (e.g. Benadryl Allergy Relief), cetirizine (e.g. Benadryl One A Day, Benadryl Allergy Children's Oral Solution, Piriteze Allergy Syrup, Pollenshield, Zirtek) and loratadine (e.g. Clarityn). Drowsiness is not usually a problem with these products, and they tend to have a longer duration of action so don't need to be taken as frequently as older compounds.