COMMENTARY

Consideration of Herbal Products in Pregnancy and Lactation

Janet R. Hardy, PhD, MPH, MSc

February 25, 2021

In recent decades, natural products have had increased consumer attention in industrialized nations. One of the challenges is that "natural" can be more of a perception than a standard. "Herbal products" is a more frequently used and perhaps a more apt term. Herbal products come in many forms, including herbs used in food preparation, teas, infusions, caplets, dried extracts, essential oils, and tinctures.

Multiple prescription medications have pharmacologically active compounds that originated from herbal products, both historically and currently. Examples include the cardiac stimulant digoxin (foxglove plant), the antimalarial quinine (Cinchona bark), and antihypertensives (Rauwolfia serpentina).

Dr Janet Hardy

Indeed, the first pharmacologically active compound, morphine, was extracted from the seed pods of opium poppies approximately 200 years ago. This demonstrated that medications could be purified from plants and that a precise dose could be determined for administration. However, herbal products are grown and harvested in varying seasonal conditions and soil types, which, over time and geography, may contribute to variability in the levels of active compound in the final products.

The importance of active compound purification and consistent precise dosage in herbal products brings up the topic of regulation. Herbal products are considered dietary supplements and as such are Food and Drug Administration regulated as a food under the 1994 Dietary Supplement Health Education Act.

Regulation as a food product does not involve the same level of scrutiny as a medication. There is no requirement that manufacturers check for purity and consistency of their product's active compound(s). Manufacturers must ensure that the claims they make about herbal products are not false or misleading. They must also support their claims with evidence. However, there is no requirement for the manufacturers to submit this evidence to the FDA. This can translate into a discrepancy between the claim on the product label and scientific evidence that the product does what it claims to do. In other words, the product may not be effective.

With uncertain efficacy, the safety of herbal products comes into focus. Very few herbal products (or their specific active compounds) have been scientifically studied for safety in pregnancy and lactation. Further, herbal products may contain contaminants. Metals such as lead and mercury occur naturally. Yet, because of human activities, both may have collected in areas where herbal products are grown.

From a safety perspective, both can be concerning in pregnancy or lactation. Lead and mercury are two examples of metal contaminants. Other contaminants may include pesticides, chemicals, and bacteria or other microorganisms. Some liquid herbal products such as tinctures contain alcohol, which should be avoided in pregnancy. An additional consideration would be the potential for herbal products, including any of their known or unknown product contents, to interact with prescribed medications or anesthesia.

Select Examples of Herbal Products

Astragalus is the root of an herb and it is used for reasons of boosting immunity, energy, and other functions. These and its purported promotion of breast milk flow (galactagogue) are unsupported. Safety concerns include irregular heartbeat and dizziness, rendering it unsafe for use in pregnancy and of unknown efficacy and safety in lactation.

Kombucha is an herbal product made from leaves (tea), sugar, a culture, and other varying products. Like many herbal products, it is both manufactured and home brewed. It is used for probiotic and antioxidant reasons. As a fermented product, kombucha may contain 0.2%-0.5% alcohol. There is no known safe level of alcohol and no known safe type of alcohol for use in pregnancy. Alcohol exposure in pregnancy can result in fetal alcohol spectrum disorders, involving a range of birth defects and life-long intellectual, learning and behavioral disorders. Alcohol found in breast milk approximates the level of alcohol found in the maternal bloodstream. Alcohol-containing products should be avoided in pregnancy and lactation.

Nux vomica is an herbal product and is used for reasons of reducing nausea or vomiting in pregnancy. It comes from the raw seeds (toxic) of an evergreen tree. It has serious safety concerns and yet it is still in use. It contains strychnine, which can harm both the pregnant individual and the developing fetus. It is not recommended in lactation.

Red raspberry leaf is a leaf, brewed and ingested as a tea. It is used for reasons of preventing miscarriage, relieving nausea and stomach discomfort, toning the uterus, reducing labor pain, increasing breast milk production, and other functions. In low doses, it appears to be safe. In high doses, it can induce smooth muscle relaxation. Efficacy has not been demonstrated with labor and delivery or in increasing breast milk production.

Tabacum is an herbal product and is used for reasons of reducing nausea or vomiting in pregnancy. Its full name is Nicotiana tabacum (tobacco) and it contains 2%-8% nicotine, which should be avoided in pregnancy. Nicotine is a health danger for the pregnant individual and can damage a developing fetus' brain and lungs.

Unless otherwise scientifically demonstrated, herbal products should be considered medications with pharmacologic activity, potential adverse effects, and potential toxicity in pregnancy and lactation. It's easy for a patient to forget about reporting any nonprescription medications during a patient-provider visit.

As a provider, purposefully asking about all over-the-counter and herbal products during each visit can prompt the patient to provide this important information. Further, it may facilitate discussion about the continuation/discontinuation of products of unknown safety and unknown benefit, culminating in the serious reflection: "Is it really worth the risk?"

For further information about the safety of herbal products, consult local Poison Control Centers, MothertoBabyMothertoBaby affiliates, and the National Institutes of Health Drugs and Lactation Database, LactMed.

Hardy is a consultant on global maternal-child health and pharmacoepidemiology, and represents the Society for Birth Defects Research and Prevention and the Organization of Teratology Information Specialists at PRGLAC meetings. Hardy has worked with multiple pharmaceutical manufacturers regarding studies of medication safety in pregnancy, most recently Biohaven Pharmaceuticals, New Haven, CT.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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