Herbs to Avoid During Pregnancy and Breastfeeding

Some herbs should be avoided during pregnancy because they contain toxic constituents, stimulate uterine contractions, affect hormonal activity, contain harmful pyrrolizidine alkaloids, or have other pharmacological actions that may pose risks to a developing embryo or fetus.

For many other herbs, the issue is different: we simply don’t have adequate human data to establish their safety during pregnancy or breastfeeding.

That distinction matters. “Not proven safe” does not necessarily mean “proven dangerous.” But pregnancy is a time when the consequences of an adverse effect can be especially serious, so a lack of reliable safety information is itself a reason for caution.

As a general rule, don’t assume that an herb is safe during pregnancy simply because it is natural or widely available. Research each medicinal herb individually before using it during pregnancy or lactation, considering the preparation, dosage, trimester, duration of use, and your individual health circumstances.

It’s easy for someone new to herbal medicine to assume that herbs are safe during pregnancy because they are natural. But medicinal plants contain physiologically active constituents, and some can affect the uterus, cardiovascular system, liver, nervous system, endocrine system, or other physiological processes relevant to pregnancy.

At the same time, herbal safety isn’t black and white.

There are thousands of plants used medicinally around the world, while only a relatively small number have a longstanding tradition of use for pregnancy-related concerns.

This is why I recommend taking a conservative approach.

Some herbs have a long history of use for pregnancy-related concerns, and several have accumulated reassuring clinical or observational safety data. Others rely more heavily on traditional use and expert clinical experience.

Medicinal plants have historically been used to ease nausea, constipation, heartburn, insomnia, and other pregnancy discomforts, and certain herbs have traditionally been used by skilled practitioners during labor.

Aviva Romm, herbalist and MD, provides excellent resources on the safe use of herbs in pregnancy. If you are a medical practitioner, I highly recommend her Botanical Medicine for Women’s Health. For personal use, consider The Natural Pregnancy book. It was one of my go-to references in my own pregnancy.

Examples of herbs traditionally used during pregnancy include:

• Ginger (Zingiber officinale)
• Peppermint (Mentha x piperita)
• Lemon (Citrus limon)
• Oatstraw (Avena sativa)
• Black haw (Viburnum prunifolium)
• Passionflower (Passiflora incarnata)
• Partridge berry (Mitchella repens)

Pregnancy isn’t the time to experiment casually with unfamiliar herbs or assume that a commonly used remedy is automatically safe. Research the individual herb carefully, including its constituents, pharmacological actions, contraindications, preparation, dosage, and pregnancy-specific safety information.

Be especially careful about where you source your herbs. Adulteration, contamination, misidentification, and inaccurate labeling introduce additional risks during pregnancy. For trusted sources, visit our Herbal Resource List. Check out our Resources at the end of this article and our Favorite Books for Women, Babies, and Children.

In many situations, an appropriately chosen botanical remedy may be worth discussing with a qualified health care provider. Err on the side of caution, do your research, and don’t be afraid to ask questions.

Keep in mind that conventional health care practitioners vary considerably in their training and familiarity with botanical medicine. If your physician, nurse, or midwife isn’t knowledgeable about herbal safety during pregnancy, consider consulting a qualified clinical herbalist or integrative practitioner with specific expertise in pregnancy and lactation—in collaboration with your prenatal health care team.

The first trimester warrants particular caution because it is a critical period of embryonic development. Exposure to teratogens—substances that can disrupt normal development, including certain herbs, pharmaceuticals, and environmental chemicals—during this vulnerable period can result in congenital abnormalities or other adverse effects.

For this reason, be especially conservative with medicinal herbs during the first trimester. Avoid unnecessary herbal remedies, and use an herb only when it’s appropriate for your individual circumstances.

Rather than memorizing one enormous list of herbs that aren’t appropriate during pregnancy, it can be more useful to understand why particular classes of herbs raise concerns.

The major categories include uterine stimulants and emmenagogues, toxic or highly bioactive herbs, stimulant laxatives, herbs with significant hormonal activity, and plants containing harmful pyrrolizidine alkaloids.

Uterine stimulants and strong emmenagogues are generally avoided during pregnancy because of their potential to stimulate uterine activity or menstrual bleeding. Depending on the herb, dose, preparation, and stage of pregnancy, these actions may theoretically or demonstrably increase the risk of pregnancy complications.

This is perhaps the most intuitive class of herbs to avoid during pregnancy.

Examples of uterine stimulant herbs to avoid in pregnancy:

• Black cohosh (Actaea racemosa)
• Blue cohosh (Caulophyllum thalictroides)
• Calendula (Calendula officinalis)
• Cotton root bark (Gossypium hirsutum, Gossypium herbaceum)
• Dong quai (Angelica sinensis)
• Feverfew (Tanacetum parthenium)
• Motherwort (Leonurus cardiaca)
• Mugwort (Artemisia vulgaris)
• Pennyroyal (Hedeoma pulegioides and Mentha pulegium)
• Yarrow (Achillea millefolium)

Note: Some herbs that are contraindicated earlier in pregnancy have traditionally been used by experienced midwives during labor. An herb’s safety therefore depends not only on the plant itself but also on timing, indication, preparation, dosage, and practitioner expertise.

Some herbs contain potent constituents that make them inappropriate for pregnancy. These include plants with known toxicity as well as medicinal herbs with powerful physiological actions or traditional contraindications during pregnancy.

I find it useful to distinguish toxic herbs from what I call highly bioactive herbs.

Toxic herbs can cause direct harm or poisoning in adults as well as embryos and fetuses. Highly bioactive herbs, on the other hand, may be used medicinally in nonpregnant adults without causing toxicity but contain potent constituents or exert physiological effects that make their use inappropriate—or insufficiently studied—during pregnancy.

Examples of bioactive and toxic herbs to avoid in pregnancy:

• Ashwagandha (Withania somnifera)
• California poppy (Eschscholzia californica)
• Comfrey (Symphytum officinale)
• Damiana (Turnera diffusa)
• Elecampane (Inula helenium)
• Foxglove (Digitalis purpurea)
• Lobelia (Lobelia inflata)
• Poke root (Phytolacca spp.)
• Rue (Ruta graveolens)
• Tansy (Tanacetum vulgare)
• Wild ginger (Asarum spp.)
• Wormwood (Artemisia absinthium)

Note: These herbs aren’t interchangeable in their chemistry or risk level. Some contain constituents with well-characterized toxicity, while others are avoided because of pharmacological activity, traditional contraindications, or animal data.

Strong stimulant laxatives are generally avoided during pregnancy. These herbs increase intestinal motility and may cause abdominal cramping, diarrhea, electrolyte disturbances, or other unwanted effects.

Examples of stimulant laxative herbs generally avoided during pregnancy include:

• Aloe latex (Aloe vera)
• Buckthorn (Rhamnus spp.)
• Cascara sagrada (Frangula purshiana, syn. Rhamnus purshiana)
• Senna (Senna alexandrina)
• Turkey rhubarb (Rheum palmatum and other Rheum species)

If you’re experiencing constipation during pregnancy, discuss it with your prenatal health care provider. Increasing dietary fiber, fluid intake, and appropriate physical activity may help, and bulk-forming fibers such as psyllium (Plantago spp.) may be appropriate for many people.

Hormonal remedies are generally avoided in pregnancy—so as not to disrupt the hormonal control of the pregnancy or the developing fetus—but herbalists and midwives debate which hormonal remedies are inappropriate or appropriate. This is why you’ll see red clover (Trifolium pratense) on some lists of herbs to avoid, and elsewhere you may see it in tonic pregnancy tea blends.

Examples of hormonal herbs to avoid in pregnancy:

• Fenugreek (Trigonella foenum-graecum)
• Hops (Humulus lupulus)
• Black cohosh (Actaea racemosa)
• Licorice root (Glycyrrhiza glabra)
• Dong quai (Angelica sinensis)
• Vitex (Vitex agnus-castus)

Note: Some of these herbs have uses at other stages of the reproductive cycle. Fenugreek and hops are used during lactation to increase milk production. Vitex is used judiciously by advanced clinicians in early pregnancy to prevent miscarriage.

Certain pyrrolizidine alkaloids (PAs) are naturally occurring plant constituents with well-established hepatotoxic potential. Some unsaturated PAs and their metabolites can cause serious liver injury and are also associated with genotoxic and carcinogenic effects.

Because pregnancy and infancy are periods of particular vulnerability, I recommend avoiding internal use of herbs containing harmful pyrrolizidine alkaloids during pregnancy and breastfeeding.

Do not apply PA-containing herbal preparations to the breasts or nipples while nursing. There are plenty of safe alternatives to these plants for every health concern, so there’s no reason to use them in pregnancy, considering the potential danger.

Examples of pyrrolizidine alkaloid-containing herbs to be avoided in pregnancy:

• Boneset (Eupatorium perfoliatum)
• Butterbur (Petasites spp.)
• Coltsfoot (Tussilago farfara)
• Comfrey (Symphytum officinale and other Symphytum species)
• Joe-Pye weed (Eupatorium and other Eupatorium species)
• Ragwort (Certain species in the Senecio genus)

The dose makes an enormous difference.

Small doses of culinary herbs used in cooking aren’t a concern; however, higher medicinal doses can be problematic in pregnancy. In some cases, basil and parsley are used in sizable quantities in food—pesto and tabbouleh, for example—and could potentially cause problems for those prone to miscarriage or preterm labor. For most people, they are not going to be an issue in pregnancy, but those who are at higher risk may choose to avoid high doses of specific culinary herbs.

Most herbalists don’t recommend giving up basil-based pesto during a healthy pregnancy, and no known reports link pesto to adverse pregnancy outcomes. However, basil is traditionally considered a uterine stimulant, and a generous serving of pesto delivers considerably more basil than the amount normally used to season a dish.

The important distinction is culinary use versus medicinal use. An herb that is safe in the small quantities typically used in food isn’t necessarily safe as a strong tea, tincture, capsule, extract, or other medicinal preparation during pregnancy. Each culinary herb has a unique safety profile during pregnancy. For instance, ginger (Zingiber officinale) has long been used to alleviate nausea.

Herbal safety remains important after pregnancy. Many botanical constituents can pass into breast milk and potentially affect a nursing baby. The amount transferred and its significance vary considerably by herb, constituent, preparation, dose, and other factors.

The infant’s age, health, gestational age at birth, maternal dosage, preparation, frequency of use, and duration of exposure can all affect risk.

Some herbs remain inappropriate while breastfeeding because of known toxicity or concern about exposure through breast milk. Others may be compatible with lactation even though they were avoided during pregnancy.

PA-containing herbs deserve particular caution. Internal use of plants containing harmful pyrrolizidine alkaloids should be avoided during breastfeeding, and PA-containing topical preparations should not be placed on the breast or nipple where an infant could ingest them. Toxic herbs should also be avoided.

Because lactation safety data are sparse for many medicinal plants, research each herb individually rather than assuming that “natural” means safe—or that every pregnancy contraindication automatically applies to breastfeeding.

The herbs covered in this article are examples, not a complete list of every herb to avoid during pregnancy or breastfeeding.

Likewise, the absence of an herb from this article does not mean that it is safe.

Research each herb individually using reliable clinical resources, and when in doubt, consult an experienced herbalist or health care provider who is knowledgeable about herbal medicine during pregnancy and lactation.

If you’d like to dig deeper, our 25-hour Online Herbal Safety Course includes a full lesson on pregnancy and lactation, along with our Herbs to Avoid in Pregnancy and Lactation Chart, a handy reference to commonly encountered Western herbs that are inappropriate for internal use during pregnancy. You’ll also receive our Herbal Safety & Contraindications Guide, which covers the herbs taught in our programs along with the most common herbs of commerce.

And because pregnancy is only one piece of herbal safety, the course also explores herb-drug interactions, toxic constituents, adulteration and contamination, allergic and topical reactions, and other important considerations for using herbal medicine safely. Our other programs contain these resources as well.