Is Lemon Balm Safe During Pregnancy?

Limited scientific evidence exists to confirm whether lemon balm is safe during pregnancy, and no major health authority has issued a clear safety endorsement for its use by pregnant women. A cross-sectional study of medicinal herb use among pregnant women in São Paulo classified lemon balm’s safety documentation as essentially unavailable, noting that the research simply has not been done to establish its status one way or the other. That gap is the honest answer, and it is frustrating for anyone hoping for a definitive yes or no. What follows is a closer look at the evidence that does exist, the forms of lemon balm that carry different risk profiles, and the practical considerations that matter if you are pregnant and wondering whether that cup of lemon balm tea is worth worrying about.

What the Research Actually Shows

The single most important thing to understand about lemon balm and pregnancy is that the research base is thin. Lemon balm (Melissa officinalis) has a long history in traditional herbal medicine for digestive complaints, anxiety, and sleep troubles, and it appears in textbook-style references alongside chamomile, ginger, and lavender as an herb “regularly used during pregnancy.” But appearing in a review chapter is not the same as being tested in a clinical trial designed to evaluate fetal safety. A Brazilian study that surveyed pregnant women’s use of medicinal herbs found that lemon balm was among the herbs consumed, yet the researchers noted that “limited scientific evidence is available to establish the safety of its use during pregnancy.”¹

This is not a case where one study says safe and another says harmful, and experts are arguing about which to believe. It is a case where the pregnancy-specific clinical trials barely exist. Most of what we know about lemon balm’s pharmacology comes from studies in non-pregnant adults, animal models, or in-vitro lab work. Translating those findings to pregnancy requires caution, because the physiological changes of pregnancy affect how the body absorbs, metabolizes, and responds to herbal compounds.

Why Pregnant Women Use It Anyway

Despite the evidence gap, lemon balm keeps showing up in surveys of herbal use during pregnancy. An Italian study of herbal product use among pregnant women found that lemon balm was among the most commonly consumed herbs, alongside chamomile, fennel, ginger, and valerian. Women reported using these herbs orally and throughout the entire pregnancy period.² The reasons are unsurprising: nausea, trouble sleeping, anxiety, and digestive discomfort are common during pregnancy, and many women prefer something they perceive as natural over pharmaceutical options.

The fact that women use lemon balm during pregnancy without widely reported adverse outcomes does offer a kind of informal signal, but it is a weak one. Self-selected use in community surveys does not control for dose, frequency, preparation method, or the many other variables that determine whether a substance causes harm. Women who drink a single cup of lemon balm tea once a week are in a different category from someone taking concentrated capsules daily, and survey data rarely makes that distinction clearly enough to draw safety conclusions.

Tea Versus Capsules Versus Essential Oil

The form in which you consume lemon balm matters more than most people realize, and this is where the risk picture starts to have some useful texture even though the pregnancy data is sparse.

A mild herbal tea made by steeping dried lemon balm leaves in hot water delivers a relatively low concentration of the plant’s active compounds, primarily rosmarinic acid and various volatile oils. This is the preparation most pregnant women are actually using when they report drinking lemon balm, and it is the form least likely to deliver pharmacologically significant doses of any single compound. That does not mean it is proven safe. It means the exposure level is low enough that most herbalists and some integrative medicine practitioners consider it a lower-risk option compared to concentrated preparations.

Capsules, tinctures, and standardized extracts are a different story. These products concentrate the active compounds, sometimes dramatically, and the dose you receive is far higher than what you would get from a cup of tea. The lack of safety data becomes a bigger problem at higher doses because the margin for unexpected effects narrows.

Essential oils present the greatest concern. A review of essential oils and their effects on the female reproductive system during pregnancy noted that major concerns include the potential for causing abortion, modulating reproductive hormones, maternal toxicity, and harm to the developing fetus.³ That review covered essential oils broadly rather than lemon balm specifically, but lemon balm essential oil contains concentrated terpenes and aldehydes (including citral and citronellal) that raise the same category of concern. Essential oils are not the same thing as herbal tea, and treating them interchangeably is one of the most common mistakes people make when thinking about herbal safety during pregnancy.

The Thyroid Question

One concern that comes up specifically with lemon balm, rather than with herbal teas in general, is its potential effect on thyroid function. Lemon balm has been traditionally used to calm an overactive thyroid, and laboratory studies have suggested that certain compounds in the plant can inhibit thyroid-stimulating hormone (TSH) binding and reduce thyroid hormone levels. For someone without thyroid problems drinking an occasional cup of tea, this effect is unlikely to be meaningful. But pregnancy places heavy demands on the thyroid. Your thyroid output increases substantially during pregnancy to support fetal brain development, and anything that suppresses thyroid function even mildly could theoretically matter, especially in the first trimester when the fetus depends entirely on maternal thyroid hormones.

No clinical study has demonstrated that lemon balm tea at normal consumption levels actually suppresses thyroid function in pregnant women. The concern is extrapolated from in-vitro data and from its traditional use as an anti-thyroid herb. If you have a pre-existing thyroid condition, particularly hypothyroidism, or if you are on thyroid medication, the theoretical concern is stronger and worth discussing with your doctor. For women with normal thyroid function who drink lemon balm tea occasionally, the risk is speculative but worth being aware of.

Heavy Metal Contamination in Herbal Teas

A risk that applies to all herbal teas, not just lemon balm, is contamination with heavy metals. A systematic review examining essential and toxic metal levels in commonly consumed herbal teas found that all of the teas studied contained detectable metals, and none met World Health Organization requirements. The review noted that while over 70 percent of the health risks were considered acceptable, the risks from arsenic and lead in certain teas were considerably higher than in others.⁴

During pregnancy, heavy metal exposure is a genuine concern because metals like lead and cadmium can cross the placenta and accumulate in fetal tissue. This is not a lemon-balm-specific problem, but it is a reason to pay attention to the source and quality of any herbal tea you drink while pregnant. Teas from reputable brands that test for contaminants are preferable to loose herbs from unknown suppliers. Organic certification reduces pesticide exposure but does not guarantee low heavy metal levels, since metals come from soil and water rather than from agricultural chemicals.

What About Aromatherapy During Pregnancy

Inhaled lemon balm essential oil, as opposed to ingested lemon balm, occupies its own category. A randomized trial tested lemon balm aromatherapy on mothers of preterm infants in a neonatal intensive care unit and found that sleep quality improved significantly over one and two weeks compared to a control group.⁵ That study involved postpartum mothers rather than pregnant women, so it does not directly answer the pregnancy safety question, but it does suggest that short-term aromatherapy exposure in a controlled setting was tolerated without reported adverse effects.

The distinction between inhaling a diluted essential oil in a well-ventilated room and applying concentrated essential oil directly to the skin or ingesting it orally is important. Inhalation delivers much smaller quantities of active compounds into the bloodstream. Some midwives and integrative practitioners are comfortable with brief aromatherapy exposure during pregnancy while advising against oral essential oil consumption. Whether that distinction is supported by rigorous evidence is another matter; most of the reasoning is based on pharmacokinetic logic rather than pregnancy-specific clinical trials.

Lemon Balm for Postpartum Pain

One area where lemon balm has been studied in a pregnancy-adjacent context is postpartum uterine cramping, sometimes called after-pains. A randomized clinical trial gave lemon balm to women experiencing after-pains and compared them to a control group. The researchers found that pain intensity decreased in both groups over time, but the decrease was significantly greater in the lemon balm group, with the differences becoming more pronounced after repeated doses.⁶ The effect was not immediate; it took until the third hour after the first dose to reach significance, but by the second day of use the difference was clear.

This is a small study, and its participants were postpartum rather than pregnant, so it does not address fetal safety. But it is one of the few controlled trials that tests lemon balm in women who have recently been pregnant, and the absence of reported adverse effects is at least mildly reassuring for the postpartum window. After-pains are common, particularly in women who have had multiple pregnancies, and a natural option that provides relief without significant side effects is something many women would welcome.

Lemon Balm and Breast Milk Production

If you are thinking about lemon balm not just during pregnancy but also while breastfeeding, it shows up in the traditional literature as a galactogogue, meaning a substance believed to help maintain or increase breast milk production. A review of herbs with galactogogue potential listed lemon balm alongside fenugreek, fennel, anise, and milk thistle as plants “known as galactogogues” and used either alone or in combination for this purpose.⁷

The evidence for lemon balm specifically increasing milk supply is traditional rather than clinical. No large trial has demonstrated that lemon balm reliably boosts lactation in humans. That said, nursing mothers around the world have used lemon balm tea for this purpose, and it appears in several commercial lactation tea blends. The same caution about dose and form applies: a cup of tea is a very different exposure than a concentrated supplement, and the lack of evidence for harm in breastfeeding populations is not the same as evidence of safety.

How to Think About the “Not Enough Evidence” Problem

The recurring theme with lemon balm and pregnancy is an evidence vacuum rather than evidence of harm. This can be difficult to navigate, because the absence of evidence and evidence of absence are genuinely different things, but they feel the same when you are trying to make a practical decision. Herbal supplements in general occupy this gray zone during pregnancy. A chapter reviewing nutraceutical and phytotherapeutic support during pregnancy put it plainly: many herbal supplements have longstanding traditional uses, but limited clinical evidence exists establishing safety and effectiveness during pregnancy and breastfeeding.¹

The practical implication is that if you occasionally drink a cup of mild lemon balm tea and it helps with nausea or sleep, the known risk level from that exposure is very low, even if it is not zero. If you are considering concentrated supplements, tinctures, or essential oils taken internally, the absence of safety data makes the risk harder to accept, because higher doses increase the chance that any unknown harmful effect actually manifests. Talking to your midwife or obstetrician before using lemon balm in any concentrated form is reasonable, not because they will have definitive safety data either, but because they can factor it into the full picture of your health, your medications, and your risk profile.

Herbal Teas Compared With One Another

Pregnant women often ask not just whether lemon balm is safe, but how it compares to other herbal teas they might reach for instead. A review of frequently used herbal teas during pregnancy emphasized the importance of caution, noting that the rapidly developing fetus is vulnerable to the adverse effects of any substance, and that potential unwanted effects carry more weight during pregnancy than at other times.⁸

Among common herbal teas, ginger has the strongest evidence base for both efficacy (specifically for nausea) and safety during pregnancy, with multiple randomized trials supporting its use. Chamomile is widely consumed and generally considered low risk in tea form, though it shares the same limited-evidence profile as lemon balm when it comes to rigorous pregnancy trials. Peppermint tea is another common choice that most practitioners consider low risk. Raspberry leaf tea is often recommended in the third trimester to prepare for labor, though its evidence base is also modest. Herbs to genuinely avoid during pregnancy include pennyroyal, blue cohosh, and large doses of licorice root, all of which have documented risks of uterine stimulation or other harmful effects.

Lemon balm sits in the broad middle category: no known serious risk in tea form, widely consumed by pregnant women, but without the specific clinical trials that would move it into the “well-studied and confirmed safe” column. If you are looking for the safest possible herbal tea during pregnancy based on available evidence, ginger tea has the most research behind it. If you prefer lemon balm for its taste or calming properties, the tea form at moderate intake is the lowest-risk way to use it, and there is no published evidence showing harm from that level of exposure.