antinomy and antihistamines

[ewx]

antinomy mentioned something on Thursday evening about antihistamines which I'd not appreciated until now - that they can take several days to build up to full effectiveness. This bubbled back to the surface this morning and I had a quick look through the instruction leaflets that come with three different ones (Piriton, Benadryl Plus and the Boots version of Loratadine). None of them tell you this. Annoying, as it means that (unless you happen to have a conversation with a relevant expert) you end up thinking that they just don't work very well on you and switch to a different pill before they've had a proper chance to do any good.