LactMed / TOXNET / NLM / NIH
http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?LACT

Thomas Hale Breastfeeding Pharmacology
http://neonatal.ttuhsc.edu/lact/

Breastfeeding Online
http://breastfeedingonline.com/

American Academy of Pediatrics Policy Statement
The Transfer of Drugs and Other Chemicals Into Human Milk
http://aappolicy.aappublications.org/cgi/content/full......

MICROMEDEX Healthcare Series
(Subscription Required)
http://www.micromedex.com/products/hcs/

US Pharmacist
http://www.uspharmacist.com/index.asp
Search: Breastfeeding OR Herbals
Herbals and Breastfeeding (Frank J. Nice)