My husband swears loratadine doesn't work for him unless he takes 20mg bid. what is the highest safe dose take?

Loratadine: while antihistamines are safe taken in high doses, 20mg twice a day of loratadine can be sedating. Whatever he symptom control he is trying to achieve, obviously an antihistamine is not controlling them. I strongly suggest he sees an allergist to address his symptoms

Recommended dose: The recommended daily dose is 10 mg. It is fairly a safe medicine, but side effects may arise in high doses. It seems like he is tolerating the 40 mg/day dose. The high dose definition may vary from patient to patient according their body tolerance. As he requires a large dose, he might benefit from adding different class medicine, so that he can avoid the side effects from unconventional doses.