I didn't know that theophylline was still being used for asthma.  We used to
use it in large doses for small children, (compared to adults) even babies,
as they were much less sensitive to the toxic effects of theophylline.  But
we stopped using it a long time ago, because once you do get toxic effects,
they can be very serious. The amount that gets into the milk, according to
Hale, is 1% of the maternal dose, which is probably not relevant clinically.
(the latter half of this is my interpretation).

Jack Newman, MD, FRCPC