The following herbs should not be used while nursing unless otherwise directed by an expert qualified in the appropriate use of the substance.
Alkanet (Alkanna tinctoria)
Aloe (Aloe vera, A. ferox, A. perryi)
Basil* (Ocimum basilicum)
Black cohosh (Cimicifuga racemosa)
Bladderwrack (Fucus vesiculosus)
Borage (Borago officinalis)
Bugleweed (Lycopus virginicus)
Cascara sagrada (Rhamnus purshiana)
Chinese rhubarb (Rheum palmatum)
Coltsfoot (Tussilago farfara)
Comfrey (Symphytum officinale)
Elecampane (Inula helenium)
Ephedra, ma huang (Ephedra sinica)
Garlic* (Allium sativum)
Joe Pye (Eupatorium purpureum)
Licorice (Glycyrrhiza glabra)
Male fern (Dryopteris filix-mas)
Purging buckthorn (Rhamnus catharticus)
Senna (Senna alexandrina)
Stillingia (Stillingia sylvatica)
Wormwood (Artemisia absinthium)
* May be safely used as a culinary seasoning.
Source: Botanical Safety Handbook (CRC, 1997)