What is the best over-the-counter antihistamine?

It is impossible to say unequivocally which of the antihistamines is the best. The effects of individual antihistamines may be perceived differently by different patients. The most troublesome side effect of these drugs is the feeling of drowsiness. Taking this criterion into account, the best antihistamines that will cause drowsiness to the least extent are fexofenadine (e.g. https://www.gdziepolek.pl/produkty/3456/allegra-tabletki-powlekane/apteki), bilastin (https://www.gdziepolek.pl/produkty/10833/clatra-allergy-tabletki/apteki), levocetericin (e.g. https://www.gdziepolek.pl/produkty/44491/lirra-gem-tabletki-powlekane/apteki). Antihistamines are divided into those that belong to the first or second generation. Substances belonging to the first generation of antihistamines have a short duration of action of about 4-6h, the second generation of drugs works longer 12-24h. Looking at these data, in chronically ill people, a good choice will be a substance belonging to the second generation of drugs, e.g. bilastin or rupatadine, which also has anti-inflammatory effects. As you can see, in order to select the best antihistamine for a particular person, several criteria and the patient's individual response to treatment should be followed. I encourage you to read the materials: https://www.gdziepolek.pl/kategorie/leki-na-alergie If you need to consult a doctor, I enclose information about the possibility of using a teleconsultation: https://www.gdziepolek.pl/telekonsultacja