Herbs are commonly consumed by pregnant and breast-feeding women, possibly because they believe that “natural products” are safer than drugs. However, even though some have been available for hundreds or thousands of years, little is known about their effects on the embryo, fetus, newborn, or nursing infant. Moreover, as unregulated products, the concentration, contents, and presence of contaminants cannot be easily determined.
Detailed reviews of the 22 most commonly used herbs discussed here can be found in “Drugs in Pregnancy and Lactation,” Briggs GG, Freeman RK, 10th ed., Philadelphia: Wolters Kluwer Health, 2014).
In the following discussions, dose, one of the two key factors that determine the risk of developmental toxicity (abnormal growth, structural anomalies, functional and/or neurobehavioral deficits, or death), is rarely reported. In addition, all herbs contain multiple chemical compounds, few of which have been studied during pregnancy or lactation.
Thus, with few exceptions, a woman who takes an herb in pregnancy should be informed that the risk to her developing baby is unknown.
By Dr. Gerald Briggs
Six herbs are considered contraindicated in pregnancy:
- black seed /kalanji
- blue cohosh
- salvia divinorum
•Arnica. The dried flowers, and sometimes the roots and rhizomes, are the parts of this perennial plant that are used topically for their anti-inflammatory and analgesic effects. There is no clinical evidence to support this use. Occasional topical use probably represents a low risk, but absorption may occur when it is applied to broken skin. The Food and Drug Administration has classified arnica as an unsafe herb and, when used orally, it is considered a poison. It is a uterine stimulant and an abortifacient. Nevertheless, in homeopathic formulations, it has been promoted for use before and during labor for internal and external bruising of the mother and newborn. In Italy, it is one of the top 10 herbs taken by women (Pharmacoepidemiol. Drug Saf. 2006;15:354-9).
• Black seed/kalanji. This herb has been used for thousands of year as a medicine, food, or spice. Because of this, it is unlikely that it causes teratogenesis. Nevertheless, its use to stimulate menstruation and its potential contraceptive properties suggest that it is contraindicated in pregnancy.
• Blue cohosh. Some of the components of this herb have been shown to be teratogenic and toxic in various animal species, so it should be avoided in the first trimester. The herb has uterine stimulant properties that are used by nurse-midwives to stimulate labor. Blue cohosh was the most frequently used herbal preparation for this purpose. However, some sources believe that the potential fetal and newborn toxicity may outweigh any medical benefit (“PDR for Herbal Medicine,” 2nd ed., Montvale, N.J.: Medical Economics, 2000:109-10; “The Review of Natural Products,” St. Louis, MO: Facts and Comparisons, 2000).
• Feverfew. This herb has been used for labor, menstrual disorders, potential miscarriage, and morning sickness; as an abortifacient; and for several other indications. Because of its antipyretic properties, it has been known as “medieval aspirin.” The doses used for these indications have not been quantified. Because of its emmenagogic (capable of provoking menstruation) activity, the herb should not be used in pregnancy.
• Salvia divinorum. This herb has hallucinogenic effects and is used in certain regions of Mexico for healing and divinatory rituals. It is also thought to have antidiarrheal properties. The herb is either smoked or chewed, or its juices are ingested. When taken orally, systemic effects are dependent upon absorption across the oral mucosa as the active ingredient is destroyed in the GI tract. Persistent psychosis has been observed in people who smoked the herb, so it is contraindicated in pregnancy.
• Valerian. A large number of preparations containing valerian are available. It has been used as a sedative and hypnotic for anxiety, restlessness, and sleep disturbances, as well as several other pharmacologic claims. Because of the risk of cytotoxicity in the fetus and hepatotoxicity in the mother, the herb should be avoided during gestation.
For the remaining 16 herbs, small, infrequent doses probably cause no harm to the mother, embryo, fetus, or newborn. Unfortunately there is very little research to support the safety, either. Nevertheless, as noted below, some of these herbs are best avoided during pregnancy.
• Chamomile. Excessive use of this herb should be avoided because it is thought to have uterine stimulant, emmenagogic, and abortifacient properties. Although controversial, some nurse-midwives prescribe chamomile teas for the treatment of morning sickness. Because the plant sources of the herb contain coumarin compounds, ingesting chamomile by pregnant women with coagulation disorders is a concern. However, the herb has been used for thousands of years, so the risk of harm, at least from occasional use, must be very rare.
• Echinacea. This herb is used topically to enhance wound healing and systemically as an immunostimulant. An IV formulation is used in Germany but is not available in the United States. It also has been recommended to assist in the prevention or treatment of viral upper respiratory tract infections. Its use in pregnancy is limited to one small study.
• Evening primrose oil. The oil contains two essential fatty acids: cis-linoleic and gamma-linolenic acid. In a national survey of nurse-midwives, it was the most frequently used herbal preparation for the induction of labor. No adverse effects have been reported in the fetus or newborn from this use. The doses used varied widely and included both oral and vaginal routes of administration. In addition, the oil has been used for rheumatoid arthritis and diabetic neuropathy, but there are no reports of these uses in pregnancy.
• Garlic. Garlic has been used for food flavoring since ancient times and appears to be safe during pregnancy. Some components cross the placenta, as shown by garlic odor in the amniotic fluid and on the newborn’s breath. Very high doses have the potential to induce menstruation or uterine contractions, but apparently these effects have not been reported.
• Ginger. No reports of ginger-induced developmental toxicity have been located. Ginger has been used as antiemetic for nausea and vomiting of pregnancy.
• Ginseng. The root is the most important part of this plant that is found throughout the world and has been used in medicine for more than 2,000 years. The herb has been promoted for multiple pharmacologic effects, including adaptogenic, CNS, cardiovascular, endocrine, ergogenic, antineoplastic, and immunomodulatory effects.
Hypertension and hypoglycemia have been reported in nonpregnant patients, but not in the limited human pregnancy data. A brief 1991 study compared 88 women who took the herb during pregnancy with 88 controls. No differences between the groups were found with regard to the mode of delivery, birth weight, low birth weight (< 2,500 ), preterm delivery (< 37 weeks), low Apgar score (< 7), stillbirths, neonatal deaths, or maternal complications (Asia Oceania J. Obstet. Gynaecol. 1991;17:379-80).
• Ginkgo biloba. The limited animal reproduction data suggest low risk, but there is no reported human pregnancy experience. Nevertheless, it is an ancient herbal preparation that is commonly used for organic brain syndrome, circulatory disorders, asthma, vertigo, and tinnitus. Because of its widespread use, it is doubtful that a major teratogenic effect would have escaped notice, but more subtle or low-incidence toxic effects may not have been detected.
• Kudzu. No human or animal data regarding pregnancy have been located. The herb has been used for more than 2,500 years for the treatment of alcohol hangover, drunkenness, alcoholism, muscle pain, and measles. Many of its chemical constituents can be found in foods. Nevertheless, high, frequent doses should be avoided.
• Nutmeg. This is a commonly used spice but, as with any herb, high doses can produce toxicity. The toxicity is caused by a chemical in the seeds, myristicin, which has anticholinergic properties. A woman at 30 weeks’ gestation misread a recipe and used a whole grated nutmeg rather than 1/8 teaspoon when making cookies. When she ate a cookie, she experienced sinus tachycardia, hypertension, and a sensation of impending doom. The fetus had tachycardia, and atropine-like poisoning was diagnosed. After about 12 hours, both mother and fetus made an uneventful recovery and a healthy infant was born at term.
• Passion flower. The name of this herb may refer to about 400 species of the genus Passiflora. It is available in both oral and topical forms and is used for nervousness, neuralgia, insomnia, pain, asthma, seizures, burns, hemorrhoids, and menopausal complaints. As with many herbs, it contains a large number of chemicals, none of which have undergone reproductive testing. No reports describing the use of this herb in human pregnancy have been located. However, because it has uterine stimulant properties, the oral formulation is best avoided in pregnancy.
• Peppermint. This popular flavoring appears to be harmless for the mother and developing baby when low, recommended doses are ingested. Peppermint oil is available in numerous topical and oral formulations. High oral doses, however, can cause significant toxicity, including death. During pregnancy, ingestion of more than the recommended doses is unsafe because of possible emmenagogic and abortifacient properties.
• Pumpkin seed. This herb, when used as a food, appears to be harmless for the mother and embryo-fetus, but no reports describing its use in pregnancy have been located. High doses, such as those used in traditional medicine or in eating disorders, should be avoided because of the potential for toxic effects from the many chemicals these seeds contain.
• Raspberry leaf. Raspberry leaf tea is commonly used by pregnant women. Nurse-midwives often prescribe the tea to treat nausea and vomiting and as a uterine tonic to shorten labor. A double-blind, randomized, placebo-controlled study evaluated the effect of raspberry leaf tablets (2 tablets/day) on pregnancy outcomes. Compared with controls, no differences were found for length of labor or stages of labor, mode of delivery, admission to the neonatal intensive care unit, Apgar score, and birth weight (J. Midwifery Womens Health 2001;46:51-9).
• Safflower. Safflower oil is commonly used in cooking and has been given for its laxative action. There are no reports describing the use of the herb in pregnancy. It is doubtful if such use would have any adverse effect on a pregnancy. Although abortifacient and emmenagogic effects have been suggested, there is no evidence supporting these effects when used as a food.
• St. John’s wort. No toxicity in pregnant humans has been reported. The use of the herb is widespread and dates back thousands of years. Thus, it is doubtful that the herb is a major teratogen or causes other elements of developmental toxicity. The herb has been used for the management of anxiety, depression, insomnia, inflammation, and gastritis. It is also used as a diuretic and, topically, for the treatment of hemorrhoids and enhanced wound healing.
• Yohimbine. The use of this herb in human pregnancies has not been reported. It has been used as an aphrodisiac and for weight loss, sexual dysfunction, and the treatment of orthostatic hypotension. Although it has no Food and Drug Administration–sanctioned indications, it is also available by prescription for male erectile dysfunction. Due to the lack of data regarding pregnancy, the herb is best avoided during pregnancy.
There are few data regarding the effects of the above herbs on a breast-feeding infant. Depending upon the herb, nursing infants will be exposed to many chemical compounds. For those herbs used as food, nursing is probably safe. The safety of the other herbs during lactation is unknown. However, toxicity has been reported in a 9-day-old term infant whose mother was taking arnica (Clin. Toxicol. 2009;47:726, abstract 120). The infant presented with lethargy, decreased milk intake, anemia, and jaundice but recovered with treatment. After the mother stopped the herb and resumed nursing, no further problems were noted in the infant.
Drugs, Pregnancy, and Lactation: Herbs
By: GERALD G. BRIGGS, B.PHARM., FCCPOctober 23, 2014
Mr. Briggs is a pharmacist clinical specialist at the outpatient clinics of Memorial Care Center for Women at Miller Children’s Hospital in Long Beach, Calif.; clinical professor of pharmacy at the University of California, San Francisco; and adjunct professor of pharmacy at the University of Southern California, Los Angeles, and Washington State University, Spokane. He also is coauthor of “Drugs in Pregnancy and Lactation,” and coeditor of “Diseases, Complications, and Drug Therapy in Obstetrics.” He had no relevant financial disclosures.
reposted by Heather Knott, RN-IBCLC