Research shows that tokishakuyakusan, a traditional Japanese herbal medicine, reduced harmful inflammation in the uterus by lowering IL-6 protein levels and boosting the body’s natural anti-inflammatory molecules in pregnant mice exposed to progesterone withdrawal. According to Gram Research analysis, the herb increased protective anti-inflammatory factors called SLPI and PGRN while suppressing uterine inflammation, without affecting fetal development. However, this is early-stage animal research; human studies are needed before recommending this herb for pregnancy support.
Researchers studied an ancient Japanese herbal medicine called tokishakuyakusan (TSS) to understand how it might protect pregnancies. Using pregnant mice, scientists found that TSS helped reduce harmful inflammation in the uterus when progesterone levels dropped. The herb worked by boosting the body’s natural anti-inflammatory molecules while reducing a key inflammatory protein. According to Gram Research analysis, this discovery could explain why this traditional medicine has been used for centuries to support healthy pregnancies, though human studies are still needed to confirm these findings.
Key Statistics
A 2026 animal study published in the American Journal of Reproductive Immunology found that tokishakuyakusan suppressed IL-6 protein expression in the uterus while increasing anti-inflammatory molecules SLPI and PGRN in pregnant mice experiencing progesterone withdrawal.
Research in pregnant mice showed that tokishakuyakusan administration did not affect fetal number, fetal weight, or placental weight despite reducing uterine inflammation, suggesting targeted anti-inflammatory effects without disrupting normal pregnancy development.
According to Gram Research analysis of this 2026 study, the herbal medicine increased the inflammatory marker G-CSF in the bloodstream while suppressing IL-6 in uterine tissue, indicating selective modulation of inflammation rather than complete suppression.
The Quick Take
- What they studied: How a traditional Japanese herbal medicine called tokishakuyakusan affects inflammation in the uterus during pregnancy, specifically when progesterone levels drop
- Who participated: Pregnant laboratory mice divided into two groups: one eating regular food and one eating food containing the herbal medicine from mating through late pregnancy
- Key finding: The herbal medicine reduced harmful inflammation in the uterus by lowering a protein called IL-6 and boosting the body’s natural anti-inflammatory molecules, without affecting baby development or placenta health
- What it means for you: This research suggests a traditional remedy may work by helping the body control inflammation during pregnancy, though these are early-stage findings in animals. Human studies would be needed before recommending this herb for pregnancy support
The Research Details
Scientists conducted an experiment using pregnant mice to test whether tokishakuyakusan could protect against inflammation caused by progesterone withdrawal. Half the mice ate regular food while the other half ate food mixed with 1% of the herbal medicine throughout their pregnancy. On day 15 of pregnancy, all mice received a drug called mifepristone that blocks progesterone’s effects, mimicking a dangerous condition that can occur in human pregnancies.
The researchers then measured inflammation markers in the mice’s blood, uterus tissue, and placenta using specialized laboratory tests. They also examined which genes were turned on or off in the uterus tissue to understand the biological mechanisms at work. This approach allowed them to see exactly how the herb was affecting the body’s inflammatory response.
This research design is important because it uses a controlled animal model to test a specific mechanism—how an herb might protect pregnancy when progesterone levels drop dangerously. By measuring both the chemical signals of inflammation and the genetic changes, researchers can understand not just whether the herb works, but how it works. This foundational knowledge is necessary before testing in humans.
This study was published in a peer-reviewed scientific journal focused on reproductive immunology, meaning experts reviewed the work before publication. The researchers used multiple measurement methods to verify their findings, which strengthens confidence in the results. However, this is animal research, so results may not directly apply to humans. The study size and specific mouse strain details would help readers assess generalizability, but these weren’t fully specified in the abstract.
What the Results Show
When mice received the drug that blocks progesterone, their bodies showed signs of widespread inflammation, including increased levels of inflammatory proteins in the blood. Mice that ate the herbal medicine showed a different pattern: they still had some inflammatory response, but the inflammation in their uterus tissue was significantly reduced compared to control mice.
Specifically, the herb lowered levels of IL-6, a key inflammatory protein in the uterus. At the same time, the herb boosted production of two natural anti-inflammatory molecules called SLPI and PGRN—these are the body’s own inflammation-fighting tools. Importantly, the herb didn’t interfere with normal pregnancy development; babies were born at normal weights and the placenta developed normally.
The herb did increase one inflammatory marker called G-CSF in the bloodstream, suggesting it wasn’t simply suppressing all inflammation. This is actually important because some inflammation is necessary for healthy pregnancy. The placenta—the organ that nourishes the baby—showed minimal changes from the herb, indicating the protective effect was specifically targeted to the uterus rather than affecting the entire pregnancy system.
Tokishakuyakusan has been used in traditional Japanese medicine for centuries to support pregnancy, but scientists haven’t fully understood how it works. This study provides the first molecular explanation for its effects, showing it acts through progesterone-responsive pathways. Previous research on other traditional herbs has suggested similar anti-inflammatory mechanisms, so this finding fits into a growing body of evidence that some traditional medicines work by helping the body regulate its own inflammatory responses.
This research was conducted in mice, not humans, so the results may not directly translate to human pregnancy. The study didn’t test different doses of the herb or compare it to other treatments. The abstract doesn’t specify how many mice were used, which makes it harder to assess the statistical strength of the findings. Additionally, this was a single study, so results would need to be confirmed by other research teams before drawing firm conclusions. Human clinical trials would be necessary before this herb could be recommended for pregnancy support.
The Bottom Line
Based on this animal research, tokishakuyakusan shows promise as a potential anti-inflammatory support during pregnancy, but confidence level is low to moderate because human studies haven’t been conducted yet. This research should not be used to self-treat pregnancy complications. Anyone considering herbal supplements during pregnancy should consult their healthcare provider, as some herbs can affect fetal development.
Researchers studying pregnancy complications and inflammation should pay attention to this work as it identifies specific biological pathways worth investigating further. Healthcare providers interested in traditional medicine may find this useful background. Pregnant people should not use this information to self-treat without medical guidance. This research is most relevant to scientists planning future human studies.
This is fundamental research exploring biological mechanisms, not a clinical trial testing real-world outcomes. Even if human studies confirm these findings, it would likely take 5-10 years of additional research before any herbal supplement could be recommended for routine pregnancy support. Benefits, if they occur in humans, would likely develop gradually over weeks of use.
Frequently Asked Questions
Does tokishakuyakusan help prevent miscarriage caused by low progesterone?
Animal research suggests tokishakuyakusan may reduce inflammation related to progesterone withdrawal, but this hasn’t been tested in humans. Current evidence is insufficient to recommend it for miscarriage prevention. Consult your healthcare provider about proven treatments for progesterone-related pregnancy complications.
Is tokishakuyakusan safe to take during pregnancy?
This study doesn’t address human safety. While the herb has traditional use in Japan, any herbal supplement during pregnancy requires medical approval. Some herbs can affect fetal development. Always discuss supplements with your obstetrician before use.
How does tokishakuyakusan reduce pregnancy inflammation?
According to this 2026 research, the herb works by boosting the body’s natural anti-inflammatory molecules (SLPI and PGRN) while reducing IL-6, a key inflammatory protein in the uterus. This suggests it helps the body regulate its own inflammation response.
When will tokishakuyakusan be available as a pregnancy treatment?
This is early-stage research in animals. Human clinical trials would be needed before any medical recommendation. If trials proceed, it typically takes 5-10 years minimum to develop and approve new treatments. Current use should only occur under medical supervision.
Can I buy tokishakuyakusan supplements for pregnancy support?
Tokishakuyakusan is available as a traditional supplement in some markets, but this research doesn’t support using it for pregnancy without medical guidance. Unregulated supplements may have variable quality or purity. Discuss any herbal use with your healthcare provider before starting.
Want to Apply This Research?
- Users interested in this research could track inflammatory markers if recommended by their healthcare provider (such as C-reactive protein levels through blood tests), measuring changes every 4-8 weeks if using any anti-inflammatory interventions
- Users could log daily intake of anti-inflammatory foods and herbs (with medical approval), noting any changes in pregnancy-related symptoms like cramping or bleeding, while maintaining regular prenatal care
- Establish a baseline inflammatory marker measurement with a healthcare provider, then track follow-up measurements quarterly while maintaining a symptom journal correlated with dietary or supplement changes
This research is preliminary animal-based science and should not be used for self-diagnosis or self-treatment. Tokishakuyakusan has not been clinically tested in pregnant humans. Anyone experiencing pregnancy complications, threatened miscarriage, or considering herbal supplements during pregnancy must consult their obstetrician or healthcare provider before taking any action. This article is for educational purposes only and does not constitute medical advice. Do not use this information to replace professional medical care or established pregnancy treatments.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.
