Is Licorice Root Safe During Pregnancy?

Licorice root, specifically the kind that contains glycyrrhizin, is not considered safe during pregnancy in anything more than trace amounts. Multiple studies from a large Finnish birth cohort have linked heavy maternal licorice consumption to preterm birth, lower cognitive scores in children, and altered pubertal development, and the biological mechanism behind these effects is well established. The concern is specific enough that Finland’s national food authority has issued formal warnings about licorice consumption during pregnancy, making it one of the few countries to single out a specific food ingredient this way.

Why Licorice Is Different From Most Herbal Teas

The active compound that causes trouble is glycyrrhizin, which is naturally present in licorice root (Glycyrrhiza glabra and related species). Your body converts glycyrrhizin into glycyrrhetinic acid, a substance that blocks a specific enzyme in the placenta. That enzyme normally converts active cortisol into an inactive form before it reaches the fetus, acting as a chemical shield that keeps the baby from being exposed to the mother’s much higher cortisol levels.

When glycyrrhetinic acid shuts down this protective barrier, maternal cortisol passes through to the fetus largely unfiltered.¹ Laboratory work using perfused human placental tissue has confirmed that glycyrrhetinic acid crosses from the maternal to the fetal side without being broken down, meaning it keeps working once it gets through.² This matters because a developing fetus is extremely sensitive to cortisol. Excess glucocorticoid exposure during critical windows of brain development can reshape how the stress-response system wires itself, with consequences that show up years later.

The Preterm Birth Connection

The most immediate pregnancy risk tied to licorice consumption is earlier delivery. A Finnish study following over a thousand pregnancies found that women with heavy glycyrrhizin intake were roughly two and a half times more likely to deliver before 38 weeks of gestation.³ When the same research team looked more specifically at true preterm birth (before 37 weeks), the risk was still more than doubled, and for very early preterm delivery (before 34 weeks) the odds were about three times higher compared to women who consumed little or no licorice.⁴

Interestingly, heavy licorice consumption did not significantly reduce birth weight. The babies were born earlier but were not smaller for their gestational age. The researchers noted that while the average shift in gestational length was modest (roughly two and a half days), this small shift at the population level was enough to double the proportion of women delivering early. That’s a useful reminder that when you’re talking about pregnancy timing, small average shifts can translate into meaningful clinical risk at the tails of the distribution.

An Italian study of nearly 400 pregnant women found a similar pattern, reporting a higher incidence of threatened miscarriage and preterm labor among regular users of licorice and chamomile compared to non-users.⁵ That study was smaller and grouped licorice with another herb, so it’s less precise, but it points in the same direction as the Finnish data.

Long-Term Effects on Children’s Cognitive Development

The Finnish cohort has been followed into childhood and adolescence, and the findings on cognitive development are striking. Children whose mothers consumed high levels of glycyrrhizin (500 milligrams per week or more) during pregnancy scored about 7 points lower on intelligence tests compared to children whose mothers had little to no exposure.⁶ Seven IQ points is a meaningful gap, roughly half a standard deviation, the kind of difference that shows up in real-world academic performance.

The same study found that these children had poorer memory performance and were more than three times as likely to show problems consistent with attention-deficit/hyperactivity disorder. An earlier analysis of the cohort at a younger age had already flagged similar patterns: children with high prenatal glycyrrhizin exposure showed decrements in verbal ability, visuospatial reasoning, and narrative memory, along with higher rates of externalizing behavior like aggression and rule-breaking.⁷ The cognitive effects appeared to follow a dose-response pattern, meaning more exposure tracked with worse outcomes.

These are observational findings, not results from a randomized trial (nobody would ethically randomize pregnant women to high licorice intake). That means confounders could play a role. But the researchers controlled for a range of factors including maternal education, smoking, and alcohol use, and the associations held. The biological plausibility is also strong: the placental enzyme inhibition described earlier gives a clear pathway from glycyrrhizin intake to fetal cortisol overexposure to altered brain development.

Effects on Pubertal Development in Girls

The long-term follow-up of Finnish children also turned up something unexpected related to growth and puberty, specifically in girls. Girls whose mothers had high glycyrrhizin exposure during pregnancy were taller, heavier, and had higher body mass index for their age. They were also closer to their adult height at the time of measurement and reported more advanced pubertal development compared to girls in the low-exposure group.⁸

Earlier puberty is not just a curiosity. It has been linked in other research to a range of health outcomes later in life, including higher rates of certain cancers and metabolic conditions. Whether the licorice-associated advancement in puberty translates into these downstream risks isn’t yet known, but the finding adds another dimension to the concern about prenatal exposure.

Maternal Blood Pressure and Pre-eclampsia Risk

Licorice doesn’t just affect the fetus. It also raises the mother’s blood pressure, a well-known effect in non-pregnant adults that carries heightened significance during pregnancy. A Danish cohort study of pregnant women found that licorice use was reflected in measurably increased blood pressure.⁹ Glycyrrhizin causes the body to retain sodium and lose potassium, effectively mimicking the hormone aldosterone. In someone who isn’t pregnant, this can cause hypertension and swelling. In pregnancy, where blood pressure disorders like pre-eclampsia are already a serious threat, the additional push can be dangerous.

A case report described severe, very early-onset pre-eclampsia in a woman who had been consuming licorice, with the authors concluding that in women with a genetic or familial susceptibility to pre-eclampsia, licorice consumption may worsen the course of the disease.¹⁰ A single case report doesn’t prove causation, but combined with the known blood-pressure-raising mechanism, it’s a warning worth taking seriously if you have any risk factors for hypertensive disorders in pregnancy.

How Much Is Too Much, and Where Is the Threshold?

The Finnish studies defined “heavy” consumption as 500 milligrams or more of glycyrrhizin per week. Translating that into real food is not perfectly straightforward because glycyrrhizin content varies enormously between products. Traditional Scandinavian salmiakki (salty licorice candy) tends to be very high in glycyrrhizin, while many licorice-flavored products sold in other countries use anise oil for flavoring and contain little or no actual licorice root. A rough guide: about 50 grams (less than two ounces) of genuine licorice candy per day could put you in the high-exposure range, depending on the brand. Some licorice teas and herbal supplements contain concentrated root extract that could deliver even more glycyrrhizin per serving.

The studies also identified a “moderate” exposure group, and the effects there were generally smaller and less consistent. That has led some researchers to describe the risk as dose-dependent, which it probably is. But the absence of a clearly established safe threshold below which there is zero risk is the reason most health authorities recommend avoiding licorice entirely during pregnancy rather than trying to identify a safe amount. When the mechanism involves disabling a key placental protective enzyme, there isn’t an obvious reason to assume small doses are harmless; it’s more that the current studies lacked the power to detect effects at lower intakes.

What About Deglycyrrhizinated Licorice (DGL)?

If you enjoy licorice flavor or have been using licorice root for digestive issues, you may have encountered DGL supplements. Deglycyrrhizinated licorice has had most of the glycyrrhizin removed during processing, which eliminates the blood-pressure-raising and enzyme-inhibiting effects that drive the pregnancy concerns. DGL is generally considered much safer in terms of the specific risks discussed here, and it’s the form often recommended by practitioners for people who want the soothing gastrointestinal effects of licorice without the hormonal side effects.

That said, “most of the glycyrrhizin removed” does not mean “all.” The residual glycyrrhizin content varies by manufacturer, and DGL supplements are not held to pharmaceutical-grade purity standards. During pregnancy, when the stakes are asymmetric (the potential harm is serious and the benefit is easily replaced by other options), most clinicians advise caution even with DGL, or at least checking the glycyrrhizin content on the specific product you’re considering.

Hidden Sources You Might Not Expect

Licorice root doesn’t only show up in candy. It appears in a surprisingly wide range of products, some of which you might consume daily without realizing. Herbal teas labeled for throat comfort, digestion, or detox frequently include licorice root as a sweetening or flavoring ingredient. Some traditional medicine formulations, particularly in Chinese and Ayurvedic practice, use licorice as a harmonizing herb in multi-ingredient blends. Certain chewing tobaccos and tobacco flavorings contain it. Even some beers, particularly Belgian and craft varieties, occasionally use licorice root.

The practical takeaway is that if you’re pregnant, it’s worth scanning ingredient lists for Glycyrrhiza glabra, Glycyrrhiza uralensis, licorice root, licorice extract, or glycyrrhizin. Anise and star anise provide a similar flavor but are entirely different plants that do not contain glycyrrhizin. “Licorice flavor” by itself is ambiguous and could come from either source.

Drug Interactions During Pregnancy

An additional concern that doesn’t get much attention is how licorice interacts with certain medications. Animal research has shown that licorice extract can amplify the toxic and teratogenic effects of cyclophosphamide, a drug used in chemotherapy and some autoimmune conditions, by boosting the expression of an enzyme that activates the drug.¹¹ This particular interaction is more relevant to the small number of women on such medications, but it illustrates a broader principle: licorice is pharmacologically active enough to change how other drugs are metabolized. It also interacts with corticosteroids, diuretics, and blood pressure medications through its aldosterone-mimicking activity. If you’re on any prescription medication during pregnancy, licorice is something to mention to your provider.

Why Many Women Don’t Know About This

Despite the fairly robust evidence base, awareness of licorice’s risks during pregnancy remains low. Survey data from Iran found that many pregnant women who used herbal medicines were unaware of potential risks, and that herbal medicine users had higher rates of pregnancy-related complications and smaller-for-gestational-age newborns.¹² The broader issue is that herbal products occupy a regulatory gray zone in most countries. They’re marketed as natural, sold without prescriptions, and rarely come with pregnancy warnings on the label.

In Scandinavian countries, where licorice candy is deeply embedded in food culture, awareness is higher. Finland has issued explicit warnings, and the topic gets media coverage during pregnancy-advice seasons. But in countries where licorice consumption is less visible or more fragmented across teas, supplements, and flavoring ingredients, pregnant women often encounter glycyrrhizin without anyone flagging it as a concern. Prenatal care guidelines in the United States and the United Kingdom don’t typically include specific counseling about licorice, focusing instead on better-known risks like alcohol, raw fish, and unpasteurized cheese. The evidence suggests licorice deserves a spot on that list, at least for women who consume it regularly.

What the Evidence Cannot Tell Us Yet

Almost all the human data on licorice and pregnancy comes from one research group tracking a single Finnish cohort. The studies are well-designed and have been published in respected epidemiology journals, but replication in other populations would strengthen the case considerably. Finnish women who eat large amounts of salty licorice candy may differ from women in other countries who encounter glycyrrhizin through herbal teas or traditional medicine, and cultural dietary patterns could introduce confounders that haven’t been fully captured.

There is also no clear data on trimester-specific vulnerability. The Finnish studies assessed overall consumption during pregnancy without pinpointing whether exposure in the first, second, or third trimester drives the outcomes. Given what we know about brain development timing, the cognitive effects might be most sensitive to exposure during particular windows, but that remains speculative. For now, the precautionary approach treats the entire pregnancy as a period of concern. There is also very limited evidence on whether occasional, low-level exposure (a single cup of licorice tea once a week, for instance) carries any measurable risk. The studies compared heavy consumers to light or non-consumers, leaving the middle ground poorly defined.