Blessed Thistle

Pregnancy

The EMA's 2023 monograph says pregnancy safety has not been established and medicinal use is not recommended because data are insufficient. The 2026 EMA public summary says its page concerns authorized herbal medicines and excludes food and food supplements. The monograph does not separate trimesters. A PubMed all-years search for Blessed Thistle or Cnicus benedictus with pregnancy terms returned zero records; this is a search result, not proof that no risk exists. The reviewed sources did not identify a human pregnancy outcome study. EMA's assessment states that reproductive toxicity testing was not performed for the preparations covered by the monograph.

Breastfeeding

LactMed's Blessed Thistle entry was last revised 20 February 2022. It describes traditional promotion as a milk booster, but says no scientifically valid clinical trials support that use. The literature includes a 2016 feasibility trial by Demirci et al. of a commercial four-herb tincture containing Blessed Thistle, fenugreek, nettle and fennel; 6 women received the tincture and 5 received meditation over 9 days, with home lactation support. The trial abstract reports 11 participants completed the study. Cragg et al.'s 2025 online, 2026 issue systematic review reports that the More Milk Plus product did not increase milk volume at day 7; the review's analysis included 9 participants, with very low certainty, and the blend cannot isolate Blessed Thistle. A separate 2019 randomized safety trial by Wagner et al. enrolled 60 healthy, fully breastfeeding women with no milk insufficiency. LactMed reports that the tea contained 35 mg of Blessed Thistle per bag and that participants drank 3 to 5 cups daily; it also contained several other herbs. The primary abstract reports no group differences in maternal or infant symptoms, infant growth or infant satisfaction. This was a mixed-product safety study, not a trial of Blessed Thistle alone or its milk-supply effect. In McBride et al.'s 2021 Australian cross-sectional survey, 1,876 women responded and 98 reported Blessed Thistle use; 8% reported side effects. The survey measured self-reported experience, not milk volume. The 2020 Cochrane review included 41 galactagogue RCTs overall; its Mother's Milk tea breastfeeding-rate evidence was very low certainty. ABM's 2018 protocol says research on herbal galactagogues remains inconclusive and it cannot recommend a specific agent.

What was tested

Pregnancy: a PubMed all-years query for Blessed Thistle or Cnicus benedictus with pregnancy terms returned 0 records; the 2023 EMA monograph states pregnancy safety has not been established and reports that reproductive toxicity testing was not performed for the covered preparations. Lactation: Demirci et al. (2016) conducted a 9-day feasibility trial in women with perceived insufficient milk; 6 were assigned a four-herb tincture containing Blessed Thistle and 5 meditation. The primary abstract reports 11 women completed the trial; Cragg et al. (online 2025, issue 2026) analyzed milk-volume data from 9 and rated the evidence very low certainty. Wagner et al. (2019) studied a multi-herb tea in 60 healthy fully breastfeeding women without milk insufficiency, comparing it with lemon verbena and following infant outcomes; it did not test Blessed Thistle alone. McBride et al. (2021) surveyed 1,876 Australian women, including 98 Blessed Thistle users, about self-reported use and effects. Cochrane (2020) reviewed 41 galactagogue RCTs; one Mother's Milk tea study reported no significant difference in breastfeeding at six months but gave no underlying data, with very low certainty. No isolated Blessed Thistle milk-supply trial was identified in the reviewed sources.