Hi Susan!
More than 750 ml. per day of tea (iced or hot), coffee, or soft drinks
containing caffeine consumed by a breastfeeding mother can make baby (and
mother) fussy, restless and hard to get / keep asleep.  The strength of the
beverage affects caffeine content and makes a big difference; so can the fact
that some mothers and / or babies are more sensitive to caffeine than others.
Re: Herbal teas:  Herbs can have side effects and be very potent not unlike
certain drugs.  Major common brands of herbal teas (less than 1 liter per
day) are generally regarded as safe. Again the strength of the brew is a
major consideration.  Excess consumption should be avoided as it can cause
side effects in mother and  / or baby.
Quote: 'However, teas marketed as "private" brands or teas brewed form
individual herbs should be used with caution as poisonous alkaloids may
render them toxic (Berlin 1996)'.
Resource: 'The Breastfeeding Answer Book, LLLI, Revised 01/97.

Leona Simoes, LLLL