Several popular herbal teas pose real risks during pregnancy, primarily because certain plant compounds can trigger uterine contractions, damage the liver, or interfere with fetal development. Caffeinated teas like black, green, and oolong are generally fine in moderation, but the limit matters: staying under 200 mg of caffeine per day (roughly two to three cups of black tea) is the standard guidance from the American College of Obstetricians and Gynecologists. Herbal teas are the bigger concern, because many contain active compounds that act like drugs in the body.
Herbal Teas That Can Trigger Contractions
The most dangerous category of herbal teas during pregnancy includes those that stimulate the uterus. These teas contain compounds that can cause the uterine muscles to contract, raising the risk of preterm labor or miscarriage. The list is longer than most people expect:
- Blue cohosh and black cohosh: Blue cohosh is particularly concerning because it can be directly toxic to the fetus in addition to triggering contractions.
- Pennyroyal: One of the most dangerous on this list. It has historically been used as an abortifacient and is toxic to the liver.
- Dong quai: Commonly used in traditional Chinese medicine, it acts as a uterine stimulant.
- Fenugreek: Often marketed for breastfeeding support, but it can stimulate the uterus during pregnancy.
- Passion flower: Used as a sleep aid, but carries uterine stimulant properties.
- Feverfew: Sometimes taken for migraines, it can provoke contractions.
- Cat’s claw: An herbal supplement popular for immune support that also stimulates the uterus.
- Rue: Toxic when consumed internally and a known uterine stimulant.
Chamomile deserves special attention because it’s one of the most commonly consumed herbal teas in the world. Both German chamomile and Roman chamomile may stimulate uterine contractions. The American Academy of Family Physicians includes chamomile on its list of teas pregnant women should avoid.
Red Raspberry Leaf Tea
Raspberry leaf tea occupies a gray area that causes a lot of confusion. It’s widely promoted as a “pregnancy tea” that prepares the uterus for labor, but the AAFP lists it among teas to avoid during pregnancy. A clinical trial in the Journal of Obstetrics, Gynecology and Cancer Research tested raspberry leaf tea on women at 40 weeks or beyond and found a trend toward increased uterine contractions, though the result wasn’t statistically significant. The concern is timing: even if the tea’s effects are mild, drinking it in the first or second trimester could be problematic. If you’re interested in using it near your due date, that’s a conversation to have with your provider, not something to start on your own early in pregnancy.
Licorice Root Tea
Licorice root contains a compound called glycyrrhizin that can cross the placenta and affect fetal development. A Finnish observational study followed children whose mothers consumed high amounts of licorice during pregnancy (more than 500 mg of glycyrrhizin per week) and found differences in some measures of physical and mental development compared to children of mothers who consumed little or none. The German Federal Institute for Risk Assessment reviewed this study and noted significant limitations, including the fact that the mothers’ licorice intake was estimated from memory rather than tracked in real time. So the evidence isn’t definitive, but the biological mechanism is plausible enough that most guidelines recommend avoiding licorice root tea during pregnancy.
Hibiscus Tea
Hibiscus tea is a common ingredient in fruit-flavored herbal blends, which makes it easy to consume without realizing it. Animal studies have raised concerns about its effects on reproductive hormones. In rats, exposure to hibiscus during pregnancy and nursing delayed the onset of puberty in offspring and increased their body weight. The proposed mechanism involves changes in stress hormones and appetite-regulating signals passed through breast milk. No human studies have confirmed these effects, but there’s also no evidence supporting its safety during pregnancy. Check the ingredient list on any fruity or “berry blend” herbal tea, as hibiscus is a frequent addition.
Teas With Liver-Toxic Compounds
Comfrey tea is one of the clearest “never drink this while pregnant” items. It contains pyrrolizidine alkaloids, compounds that damage liver cells by destroying the small veins inside the liver. This can lead to a condition where scar tissue blocks blood flow through the organ, eventually progressing to cirrhosis. These alkaloids also cause DNA damage in liver cells, which is a concern for anyone but especially for a developing fetus. Many countries have restricted the sale of comfrey for internal use. Wormwood (the herb used in absinthe) contains potentially neurotoxic compounds and should also be avoided. Boldo tea, less common in the U.S. but used in South American traditions, contains both toxic compounds and a sedative alkaloid.
Caffeinated Teas: The 200 mg Rule
Black tea, green tea, and oolong tea are not off-limits during pregnancy, but their caffeine content matters. The threshold is 200 mg per day. A standard 8-ounce cup of black tea contains roughly 40 to 70 mg of caffeine, green tea about 20 to 45 mg, and oolong falls somewhere in between. That means two to three cups of black tea per day is typically within the safe range, while four or five cups could push you over.
One additional consideration with traditional teas is metal content. Testing by EPA researchers found that aluminum levels in brewed black tea frequently exceeded the secondary drinking water limit of 0.2 mg per liter, and chromium levels in many herbal and traditional teas exceeded Canadian safety limits. For occasional tea drinkers this isn’t a major concern, but if you’re drinking several cups daily, the cumulative metal exposure adds up.
Herbal Teas That Are Generally Safe
Not all herbal teas are risky. Ginger tea is one of the best-supported options during pregnancy and is commonly recommended for nausea. Teas made with citrus peel, lemon balm, and rose hips are also considered safe in moderation. The key word is moderation: even safe herbal teas should be consumed in reasonable amounts, not as your primary fluid intake throughout the day.
The broader issue with herbal teas is that they’re not regulated the same way as food or medicine. There are no standardized purity requirements, and what’s on the label doesn’t always match what’s in the bag. Blends marketed as “pregnancy tea” or “women’s wellness tea” sometimes contain ingredients from the avoid list, including chamomile, raspberry leaf, or hibiscus. Read ingredient lists carefully, and stick to single-ingredient teas from brands you trust when possible.