Table 1.

Road safety categorisation of H1 antihistamine drugs based on blood alcohol equivalent doses [21, 22]

Generation H1 antihistamines	I No significant effect (DE to BAC: < 0.5 g/l; < 0.5 per mil)	II Low or moderate effect (DE to BAC: 0.5–0.8 g/l; 0.5–0.8 per mil)	III Strong effect, potentially dangerous (DE to BAC: > 0.8 per mil)
1st Generation	–	Ketotifen	Clemastine, diphenhydramine, promethazine
2nd Generation	Azelastine, bilastine, desloratadine, ebastine, fexofenadine, levocetirizine, loratadine, rupatadine	Cetirizine, mizolastine	–

per mil is defined as parts per thousand

BAC blood alcohol content, DE dose equivalent