Herbs Contraindicated in Pregnancy, by Mechanism
Western herbalism does not give in pregnancy the emmenagogues and uterine stimulants, the anthraquinone purgatives, the pyrrolizidine-alkaloid plants, the essential oils taken internally, the strong bitters and alkaloids, the hormonally active plants in medicinal dose, and the toxic plants of the tradition. It does give, with a clear dose, Raspberry leaf, Nettle, Ginger in small amounts, Chamomile, Oat, and a handful of others and treats every culinary herb in cooking quantity as food. The list is the one the herbals and the modern monographs carry, sorted by mechanism, since the mechanism tells why a plant absent from it is or is not safe.
Emmenagogues and uterine stimulants
An emmenagogue brings on menstruation; a uterine stimulant contracts the womb. Both are avoided throughout pregnancy, and the strong ones are the classical abortifacients. Pennyroyal, Mentha pulegium, whose essential oil is also a liver poison; Tansy, Tanacetum vulgare; Rue, Ruta graveolens; Mugwort, Artemisia vulgaris, and Wormwood, Artemisia absinthium; Savin, Juniperus sabina, and Juniper berry, Juniperus communis; Blue Cohosh, Caulophyllum thalictroides; Black Cohosh, Actaea racemosa, except at term in the hands of a midwife; Cotton root bark, Gossypium herbaceum; Birthwort, Aristolochia species, which is in any case no longer used at all because its aristolochic acid destroys the kidney; Motherwort, Leonurus cardiaca; Yarrow, Achillea millefolium, in medicinal dose; Feverfew, Tanacetum parthenium; Angelica, Angelica archangelica, and Dong Quai, Angelica sinensis; Goldenseal, Hydrastis canadensis; Myrrh, Commiphora myrrha; Lovage, Levisticum officinale; and Parsley, Petroselinum crispum, as root or seed in medicinal quantity.
Anthraquinone purgatives
Senna, Senna alexandrina; Cascara, Frangula purshiana; Buckthorn, Frangula alnus; Aloe latex, Aloe vera; and Rhubarb root, Rheum palmatum, are the anthraquinone laxatives, and they are avoided because the griping of the bowel reflexly stimulates the uterus. The gentle bulk and bitter remedies are used instead: Psyllium, Plantago ovata, and Dandelion root, Taraxacum officinale.
Pyrrolizidine alkaloids
Comfrey, Symphytum officinale; Coltsfoot, Tussilago farfara; Borage leaf, Borago officinalis; Butterbur, Petasites hybridus; and Life Root, Senecio aureus, contain pyrrolizidine alkaloids that injure the liver and cross the placenta, and they are not taken internally in pregnancy or at any other time in current practice. Comfrey on unbroken skin, for a short course, is the one use the modern monographs allow, and even that is withheld in pregnancy.
Essential oils, strong bitters, and alkaloids
No essential oil is taken internally in pregnancy; Thuja, Sage oil, Wintergreen, and Pennyroyal oil are the dangerous ones, and the culinary leaves of sage and thyme in food are not the concern. The bitter and alkaloidal plants avoided are Barberry, Berberis vulgaris, and Oregon Grape, Mahonia aquifolium, for their berberine; Lobelia, Lobelia inflata; Ma Huang, Ephedra sinica, whose Western use ended with the regulatory bans of the early 2000s; Bloodroot, Sanguinaria canadensis; and Kava, Piper methysticum. The toxic plants of the materia medica, Aconite, Foxglove, Hellebore, Poke root in more than drop doses, are not home remedies at any time.
Hormonally active plants and the debated ones
Licorice, Glycyrrhiza glabra, in medicinal dose and over weeks is avoided for its effect on blood pressure and potassium and on the pregnancy itself; a cup of a blend that carries a pinch of it is not the concern. Vitex, Vitex agnus-castus, acts on the pituitary and is stopped when pregnancy is confirmed, though some practitioners continue it through the first trimester for a person with a history of early loss, which is a debate inside the tradition. Ginseng, Panax ginseng, is avoided by the monographs; Red Clover, Trifolium pratense, in medicinal quantity likewise. St John's Wort, Hypericum perforatum, is avoided because there is no established dose and because of its drug interactions. Ginger, Zingiber officinale, is the plant the tradition disagrees about most: the Commission E monograph withheld it from pregnancy, and the later monographs and the midwives' practice give it for nausea at up to 1 gram of the dried root a day, which is the figure used now.
What the tradition gives
| Plant | Preparation | Adult dose | When |
|---|---|---|---|
| Raspberry leaf, Rubus idaeus | infusion, 1 to 2 teaspoons per cup | one to three cups daily | second and third trimester |
| Nettle, Urtica dioica | long infusion, 30 g per litre, four hours | one to two cups daily | throughout |
| Ginger, Zingiber officinale | dried root, infusion or capsule | up to 1 g per day | for nausea |
| Chamomile, Matricaria chamomilla | infusion, 1 teaspoon per cup | one to three cups daily | throughout |
| Milky Oat, Avena sativa | fresh tincture, 1:2 | 2 to 4 ml, three times daily | throughout |
| Lemon Balm, Melissa officinalis | infusion, 1 to 2 teaspoons per cup | one to two cups daily | throughout |
| Slippery Elm, Ulmus rubra | powder in water | 1 teaspoon as needed | for heartburn |
Raspberry leaf is the partus preparator of the tradition, toning the uterus for labour, and the herbals hold it to the second half of pregnancy. Slippery elm is an at-risk tree and is bought from a cultivated or salvage source.
Not medical advice.