St. John's Wort
HerbalAlso called · 9 names▾▴
St Johns Wort, Saint John's Wort, Saint Johns Wort, Hypericum, Hypericum perforatum, Klamath weed, goatweed, Johanniskraut, Perikon
Herbal supplement (depression and mood)
Herbs and supplements are not FDA-approved before sale. About these sources
- Capsule/tablet
- Liquid extract
- Tea
- Topical
- Powder
Research strength: 3 / 5
MotherToBaby says three studies did not report an increase in birth defects. Kolding et al. (2015) recorded malformations in 3 of 37 exposed babies (8.1%) versus 3.3% of controls; the difference was not statistically significant (p=0.13). A German claims study by Schafer et al. (2021) found coded major malformations in 18 of 312 babies linked to exposed pregnancies, with 17 exposed in the first trimester; the authors said these findings need cautious interpretation and further study. EMA says human safety is not established, notes findings from animal studies, and does not recommend use during pregnancy; NCCIH warns of a possible increase in birth-defect risk. MotherToBaby and NCCIH also report interactions with many medicines, including birth-control pills. Ask your provider about your situation.
Last reviewed: 2026-10-16
Sources
- MotherToBaby: St. John's WortTeratology service
- Kolding et al., Reproductive Toxicology 2015: Hypericum perforatum use during pregnancy and pregnancy outcomeUS government
- Schafer et al., Reproductive Toxicology 2021: Characterization of pregnancies exposed to St. John's wort and their outcomesUS government
- European Medicines Agency: EU herbal monograph on Hypericum perforatum L., herbaEU agencyEuropean guidance
- NCCIH: St. John’s Wort: Usefulness and SafetyUS government
Research strength: 3 / 5
Kolding et al. (2015) found no difference in preterm birth in its cohort, but it included only 38 exposed pregnancies and did not settle outcomes by trimester. The 2021 German claims study included 496 pregnancies, most with first-trimester exposure, and did not provide a reliable separate estimate for second-trimester use. EMA says human safety is not established, notes findings from animal studies, and does not recommend use during pregnancy; NCCIH warns of a possible increase in birth-defect risk. MotherToBaby reports that St. John’s wort has not been well studied in pregnancy. MotherToBaby and NCCIH also report interactions with many medicines, including birth-control pills. Ask your provider about your situation.
Last reviewed: 2026-10-16
Sources
- MotherToBaby: St. John's WortTeratology service
- Kolding et al., Reproductive Toxicology 2015: Hypericum perforatum use during pregnancy and pregnancy outcomeUS government
- Schafer et al., Reproductive Toxicology 2021: Characterization of pregnancies exposed to St. John's wort and their outcomesUS government
- European Medicines Agency: EU herbal monograph on Hypericum perforatum L., herbaEU agencyEuropean guidance
- NCCIH: St. John’s Wort: Usefulness and SafetyUS government
Research strength: 3 / 5
MotherToBaby says human pregnancy data are limited, and the available studies do not provide a distinct third-trimester risk estimate. In Schafer et al. (2021), 420 of 496 exposed pregnancies had first-trimester exposure; the study authors cautioned that the reported pregnancy outcomes need further study. EMA says human safety is not established, notes findings from animal studies, and does not recommend use during pregnancy; NCCIH warns of a possible increase in birth-defect risk. The available human studies do not establish a specific late-pregnancy effect. MotherToBaby and NCCIH also report interactions with many medicines, including birth-control pills. Ask your provider about your situation.
Last reviewed: 2026-10-16
Sources
- MotherToBaby: St. John's WortTeratology service
- Schafer et al., Reproductive Toxicology 2021: Characterization of pregnancies exposed to St. John's wort and their outcomesUS government
- European Medicines Agency: EU herbal monograph on Hypericum perforatum L., herbaEU agencyEuropean guidance
- NCCIH: St. John’s Wort: Usefulness and SafetyUS government
St. John's Wort — Breastfeeding
Research strength: 2 / 5
MotherToBaby reports small milk transfer in five mothers breastfeeding full-term infants 10 to 22 weeks old, with no infant effects reported; other plant compounds have not been measured in milk. In Lee et al. (2003), mothers reported colic in two infants, drowsiness in two, and lethargy in one among 33 exposed mothers; no infant needed treatment, and the difference was significant only versus the disease-matched group. Klier et al. (2006) measured low hyperforin exposure in five mothers and two infants, with no side effects reported in those infants. LactMed says experience is limited and an alternative may be preferred, especially for newborn or preterm infants; EMA does not recommend use during lactation. MotherToBaby and NCCIH also report medicine interactions, and LactMed says effects on milk supply are unclear. Ask your provider about your situation.
Last reviewed: 2026-10-16
Sources
- LactMed (NIH): St. John's WortUS government
- MotherToBaby: St. John's WortTeratology service
- Lee et al., Journal of Clinical Psychiatry 2003: The safety of St. John's wort during breastfeedingUS government
- Klier et al., Journal of Clinical Psychiatry 2006: St. John's wort and breastfeeding milk concentrationsUS government
- European Medicines Agency: EU herbal monograph on Hypericum perforatum L., herbaEU agencyEuropean guidance
- NCCIH: St. John’s Wort: Usefulness and SafetyUS government
Pregnancy
MotherToBaby reports limited pregnancy research and says three studies did not report an increase in birth defects. The primary abstracts show important detail: Moretti et al. (2009) prospectively followed 54 exposed pregnancies and 108 comparator pregnancies; major malformation rates were 5%, 4%, and 0%, and live-birth and preterm-birth rates did not differ. Kolding et al. (2015) compared 38 exposed pregnancies with 90,128 women; preterm birth did not differ, while malformations were reported in 8.1% of exposed babies versus 3.3% of controls, based on three cases (p=0.13). Schafer et al. (2021) analyzed insurance claims for 496 exposed pregnancies; 420 had first-trimester exposure, 11% ended in non-live births, and 18 of 312 linked babies had coded major malformations, 17 after first-trimester exposure. The 2021 authors said the non-live birth and malformation findings need cautious interpretation and further study; their abstract does not separate non-live births into miscarriages or other outcomes. Human evidence is observational and does not establish cause. EMA states pregnancy safety is not established, reports findings from animal studies, and does not recommend use during pregnancy; NCCIH says the herb may increase birth-defect risk. MotherToBaby says it is not known whether St. John's wort increases miscarriage risk. Moretti et al.'s abstract reports no difference in live-birth rates but gives no miscarriage counts; Schafer et al. report non-live births without separating miscarriage from other outcomes, so those abstracts do not establish a miscarriage-specific effect.
Breastfeeding
LactMed reports that hypericin and hyperforin are poorly excreted into milk and that other components have not been measured. Klier et al. (2006) studied five mothers taking 300 mg three times daily and their infants; relative infant doses of hyperforin were 0.9% to 2.5%, and no side effects were seen in the two infants with plasma samples. Lee et al. (2003) followed 33 breastfeeding women taking St. John's wort, 101 disease-matched controls, and 33 age- and parity-matched controls. The exposed group had two reported cases each of colic and drowsiness and one of lethargy; no infant required treatment. The difference was statistically significant versus disease-matched controls (p<0.01), but not versus the healthy matched controls (p=0.20). The study found no significant difference in reported milk production or infant weight. LactMed notes little published experience and says an alternative may be preferred, especially for newborn or preterm infants. EMA does not recommend use during lactation because human safety is not established and animal studies showed reproductive findings in animals.
St. John's wort is Hypericum perforatum, a flowering plant sold as an herbal supplement. MotherToBaby lists tablets or capsules, liquid extracts, tea, creams, and ointments, and says the amount and quality of plant compounds can vary with soil, harvest, drying, and storage. LactMed identifies hypericin, hyperforin, and flavonoids such as quercetin; only hypericin and hyperforin have been measured in human milk. MotherToBaby and NCCIH note that in the United States dietary supplements are not approved by FDA before sale and do not have the same preparation standards as prescription medicines.
What was tested
Pregnancy evidence includes small prospective cohorts and a German insurance-claims analysis; these studies measured pregnancy outcomes rather than assigning exposure. The 2021 claims analysis covered 496 exposed pregnancies but had no unexposed comparison group in its abstract and did not distinguish kinds of non-live birth. Breastfeeding evidence includes one observational cohort with 33 exposed mothers and 134 controls, plus small studies measuring hyperforin in milk or infant plasma, including five mothers and two infants. Animal studies are part of EMA's reason for its precautionary pregnancy and lactation wording. No human study reviewed establishes a causal link or a trimester-specific pregnancy risk estimate.
Pregnancy recommendations and the meaning of limited human outcome studies
- Source A says
- EMA says human pregnancy safety is not established, cites reproductive findings in animals in animals, and does not recommend use. NCCIH says St. John's wort may increase birth-defect risk. (European Medicines Agency: EU herbal monograph on Hypericum perforatum L., herba, NCCIH: St. John’s Wort: Usefulness and Safety)
- Source B says
- MotherToBaby reports that three studies did not find a statistically significant increase in birth defects. The Danish cohort observed a higher rate based on three exposed cases, and the German claims study reported coded malformations and non-live births that its authors said need cautious interpretation and further study. (MotherToBaby: St. John's Wort, Kolding et al., Reproductive Toxicology 2015: Hypericum perforatum use during pregnancy and pregnancy outcome, Schafer et al., Reproductive Toxicology 2021: Characterization of pregnancies exposed to St. John's wort and their outcomes)
- Why they differ
- EMA and NCCIH emphasize animal findings and a precautionary approach. The human studies are observational, small or based on claims, and use different populations and comparisons. The 2021 claims study primarily covered first-trimester exposure and its abstract does not establish an unexposed comparison or cause.
- What the evidence shows overall
- Human outcome findings are limited and mixed. The studies do not establish cause, but the claims analysis reported outcome patterns its authors considered important enough to study further. EMA and NCCIH take a more precautionary view based on the animal findings and uncertainty.
How cautious guidance should be during breastfeeding
- Source A says
- EMA says human lactation safety is not established, cites findings from animal studies, and does not recommend use during lactation. (European Medicines Agency: EU herbal monograph on Hypericum perforatum L., herba)
- Source B says
- LactMed reports low milk transfer of the measured compounds and says an alternative may be preferred, especially for newborn or preterm infants. MotherToBaby reports no effects in five infants in one study, but a separate cohort reported colic, drowsiness, and lethargy without treatment. (LactMed (NIH): St. John's Wort, MotherToBaby: St. John's Wort, Lee et al., Journal of Clinical Psychiatry 2003: The safety of St. John's wort during breastfeeding, Klier et al., Journal of Clinical Psychiatry 2006: St. John's wort and breastfeeding milk concentrations)
- Why they differ
- EMA uses a precaution based on unestablished human safety and animal findings. The human lactation data are small, measure only selected compounds, and include one observational report of infant symptoms whose cause is uncertain.
- What the evidence shows overall
- Human lactation studies show low transfer of measured compounds but do not cover all plant compounds or exclude infant effects. One small cohort reported infant symptoms, though none required treatment and the difference was not statistically significant versus healthy matched controls.
- MotherToBaby says healthcare providers can discuss treatment options that have been better studied during pregnancy and advises discussing supplement or medicine changes with the care team. (MotherToBaby)
- EMA advises patients taking prescription medicines to consult a doctor or pharmacist before taking Hypericum; its monograph also describes reduced hormonal-contraceptive concentrations and possible loss of contraceptive effectiveness. (European Medicines Agency)
- LactMed says an alternative may be preferred during breastfeeding, especially while nursing a newborn or preterm infant. (LactMed)
General research, not specific to pregnancy.
St. John's wort can change how other medicines work. NCCIH and EMA describe interactions with hormonal contraceptives and other medicines, and NCCIH notes that combining it with some antidepressants can cause serious serotonin-related effects. NCCIH also describes sun-related skin reactions after large oral doses or skin application.
- EMA says St. John's wort can lower the levels of medicines processed by several liver enzymes and transport proteins. It reports reduced hormonal-contraceptive levels and effectiveness, interactions with some transplant, HIV, cancer, and blood-thinning medicines, and possible serotonin syndrome with serotonergic medicines. (European Medicines Agency: EU herbal monograph on Hypericum perforatum L., herba, NCCIH: St. John’s Wort: Usefulness and Safety)
- NCCIH says large oral doses or skin application may cause strong skin reactions after sun exposure. (NCCIH: St. John’s Wort: Usefulness and Safety)
- MotherToBaby says plant-compound amounts can vary with growing and processing. It and NCCIH note that dietary supplements are not approved by FDA before sale in the same way as prescription medicines. (MotherToBaby: St. John's Wort, NCCIH: St. John’s Wort: Usefulness and Safety)
- MotherToBaby: St. John's WortTeratology serviceSecondary
- LactMed (NIH): St. John's WortUS governmentSecondaryPage dated 2025-04-15
- European Medicines Agency: EU herbal monograph on Hypericum perforatum L., herbaEU agencySecondaryPage dated 2022-11-23Independent checkEuropean guidance
- NCCIH: St. John’s Wort: Usefulness and SafetyUS governmentSecondaryIndependent check
- Moretti et al., Reproductive Toxicology 2009: Evaluating the safety of St. John's Wort in human pregnancyUS governmentPrimaryIndependent check
- Kolding et al., Reproductive Toxicology 2015: Hypericum perforatum use during pregnancy and pregnancy outcomeUS governmentPrimaryIndependent check
- Schafer et al., Reproductive Toxicology 2021: Characterization of pregnancies exposed to St. John's wort and their outcomesUS governmentPrimaryIndependent check
- Lee et al., Journal of Clinical Psychiatry 2003: The safety of St. John's wort during breastfeedingUS governmentPrimaryIndependent check
- Klier et al., Journal of Clinical Psychiatry 2006: St. John's wort and breastfeeding milk concentrationsUS governmentPrimaryIndependent check
Last reviewed 2026-10-16
Independent check 2026-10-16
Not yet clinician-reviewed
Ask your provider about your situation.