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Key takeaways
• No published safety data exist for fisetin supplementation during pregnancy or breastfeeding.
• Ordinary dietary fisetin intake from strawberries, apples, and grapes is presumably safe — fisetin is a normal component of a healthy diet at dietary levels.
• Concentrated capsule doses (100 mg and higher) are not recommended during pregnancy or breastfeeding without explicit obstetric guidance.
• Fisetin’s known biological activities — senolytic clearance of senescent cells, modest anti-inflammatory effects, mild CYP450 activity — raise theoretical concerns during pregnancy that have not been formally studied.
• Whether fisetin crosses into breast milk in humans is unstudied. As a small lipophilic molecule, some transfer is likely, but the extent and clinical significance are unknown.
• Women planning pregnancy or actively trying to conceive should discontinue fisetin supplements and rely on dietary sources only.
Quick answer
There is no published safety data for fisetin supplementation during pregnancy or breastfeeding. Ordinary dietary intake from strawberries and other fisetin-containing fruits is presumably safe — fisetin is a normal component of a healthy diet consumed daily at low levels. Concentrated capsule doses (typically 100 mg and higher) have not been studied in pregnant or lactating women and should not be used without explicit obstetric guidance. The known biological activities of fisetin — senolytic activity, mild CYP450 activity, effects on cellular signalling pathways relevant to fetal development — raise theoretical concerns that have not been formally addressed. Women who are pregnant, breastfeeding, or planning pregnancy should discontinue fisetin supplements. For the broader safety picture, see our side effects and safety article.
The dietary distinction — strawberries vs capsules
The single most important distinction in this article is the difference between dietary fisetin and supplemental fisetin.
Fisetin at dietary levels is a completely normal part of human intake. A typical Western diet delivers 0.4 to 1 mg of fisetin per day (2). A generous strawberry serving delivers approximately 40 mg. These levels have been consumed by humans for as long as humans have eaten fruit. There is no plausible reason to consider dietary fisetin dangerous in pregnancy — doing so would mean restricting normal food choices including strawberries, apples, and grapes, which are otherwise recommended pregnancy foods for their vitamin C, folate, and fibre content.
Fisetin at supplement doses is a different exposure entirely. A 500 mg fisetin capsule delivers 500 to 1,250 times the average dietary daily intake in a single dose. This exposure has been characterised in a small number of non-pregnant healthy adults (5) and in a nursing home population (COVID-FIS, older adults with acute illness). It has not been characterised in pregnant women, in women trying to conceive, in the perinatal period, or in lactating women. The pharmacology of a compound at 500-fold above dietary intake may differ meaningfully from the pharmacology at dietary intake — this is a general principle of nutrient pharmacology, not a specific fisetin concern.
The practical translation: keep the strawberries. Stop the capsules.
Why the caution matters — theoretical concerns
Four biological properties of fisetin raise theoretical concerns in pregnancy. None have been demonstrated to cause harm in humans, but the absence of controlled data means clinicians default to caution.
Senolytic activity
Fisetin’s primary pharmacological identity is senolytic — selective killing of senescent cells. Cellular senescence plays specific and evolutionarily important roles in pregnancy: senescence is involved in embryonic morphogenesis, placental development, and labour onset (6). A recent 2023 review documented these roles and identified pregnancy as a physiological state in which senescent cells are not simply harmful but functionally necessary for normal development. Pharmacologically clearing senescent cells during pregnancy is not a well-characterised intervention, and the theoretical concern is that senolytic activity could disrupt normal developmental programmes. This is speculative but sufficient reason for caution.
CYP450 activity
Fisetin is a CYP2C8 substrate and mild inhibitor of several other cytochromes P450. Placental transfer of drugs and their metabolism by placental enzymes is a complex system that regulates fetal drug exposure. Fisetin’s effects on placental CYP activity are not characterised, and theoretical interference with placental drug metabolism could alter fetal exposure to co-administered medications. Our drug interactions article covers the CYP profile in detail.
Signalling pathway effects
Fisetin modulates several intracellular signalling pathways relevant to fetal development — PI3K/AKT, NF-κB, Nrf2, and others (8). These pathways regulate normal proliferation, differentiation, and apoptosis during embryogenesis. The concentrations of fisetin achieved by dietary intake are almost certainly too low to affect these pathways meaningfully; the concentrations achieved by supplement doses may not be.
Anti-oxidant and anti-inflammatory activity
Fisetin’s general antioxidant and anti-inflammatory activity is well established. In the abstract, more antioxidant activity sounds beneficial in pregnancy. In practice, oxidative and inflammatory signalling are actively regulated during normal embryonic development, and pharmacological manipulation may not simply be beneficial. This is one of several reasons that high-dose vitamin C, high-dose vitamin E, and other antioxidant supplement interventions have shown mixed or negative results in pregnancy trials — not because antioxidants are harmful but because sustained supraphysiological antioxidant tone in developmental biology is not the same as protection (3).
Breastfeeding — what we know and don’t
Breastfeeding safety data for fisetin supplementation is essentially absent. Two considerations apply.
Whether fisetin transfers into breast milk. Small lipophilic molecules typically transfer into breast milk to some extent. Fisetin’s molecular weight (286 daltons), lipid solubility, and lack of ionic charge suggest that some milk transfer is likely. The extent has not been measured. Given the poor oral bioavailability of fisetin, the maternal plasma concentrations available for milk transfer are also small, which limits the magnitude of infant exposure.
Whether infant exposure would be problematic. Also unknown. Infants routinely receive small quantities of many maternal dietary flavonoids through breast milk, and this is not generally considered harmful. Whether supplemental-dose fisetin exposure differs qualitatively from dietary flavonoid exposure through milk has not been studied.
The practical guidance: dietary fisetin intake (strawberries and other fruits) is safe during breastfeeding. Supplement doses are not recommended in the absence of safety data. Women who are breastfeeding and taking fisetin supplements should discontinue and consult their obstetrician or paediatrician.
Fertility and preconception
Fisetin’s effects on human fertility are unstudied. The 2025 Wang review documented emerging preclinical evidence for fisetin’s effects on ovarian follicular biology, endometrial senescence, and other reproductive tissues (1). Some of these effects are theoretically beneficial — for example, clearing senescent cells from ageing ovaries — but the human clinical translation is unknown.
Women actively trying to conceive should discontinue fisetin supplements as a precaution. The rationale is not evidence of harm but the absence of safety data during the peri-conceptional window, which is developmentally critical. Discontinuation for a minimum of one full menstrual cycle before attempted conception is a sensible general recommendation.
For men, fisetin’s effects on sperm parameters and fertility are also unstudied. The theoretical concerns are smaller — no developmental biology in play — but formal reproductive toxicology data are absent. Men actively trying to conceive with their partner may wish to discontinue as a precaution during the active conception period, though this is a more discretionary recommendation than for women.
Discontinuation guidance
If you discover you are pregnant while taking fisetin, discontinue immediately and inform your obstetric team at your next appointment. Do not panic — there is no evidence that ordinary supplement doses of fisetin cause harm — but the responsible action is to stop supplementation and revert to dietary intake only. Ongoing pregnancy monitoring proceeds as usual.
If you are already breastfeeding and discover fisetin in your supplement stack, discontinue and consult your paediatrician. No specific screening of the infant is required in the absence of concerning symptoms.
What we still don't know
• Whether supplement-dose fisetin during pregnancy causes any developmental harm or is entirely benign. The absence of trial data means the honest answer is uncertain.
• Whether fisetin’s senolytic activity meaningfully interferes with the normal roles of cellular senescence in pregnancy and labour (6).
• The extent and clinical significance of fisetin transfer into breast milk. Not measured.
• Whether fisetin at supplement doses affects fertility in either direction — pro-fertility (via ovarian senescent-cell clearance) or anti-fertility (via interference with normal follicular biology).
• Whether fisetin exposure during pregnancy influences long-term offspring health outcomes. Not studied.
Bottom line
Fisetin supplementation during pregnancy and breastfeeding has not been studied. Ordinary dietary intake from strawberries and other fruits is safe and should be continued. Concentrated capsule doses (100 mg and higher) are not recommended during pregnancy, breastfeeding, or the peri-conceptional period. Women who become pregnant while taking fisetin should discontinue and inform their obstetric team. Women planning pregnancy should discontinue at least one menstrual cycle before attempted conception. The rationale is not documented harm but the absence of safety data — in developmental biology, absence of evidence is not evidence of absence. For the broader safety picture, see our side effects and safety article. For the full clinical context, see our complete clinician’s guide.
Frequently asked questions
Is fisetin safe in pregnancy?
Dietary intake from fruits is safe. Supplement doses have not been studied and are not recommended without obstetric guidance.
I took fisetin before I knew I was pregnant. Should I worry?
There is no evidence that supplement-dose fisetin causes fetal harm. Discontinue now, inform your obstetric team at your next appointment, and continue with routine monitoring.
Can I eat strawberries in pregnancy?
Yes. Strawberries are a good pregnancy food — vitamin C, folate, fibre, and antioxidants at levels the body has always seen. Fisetin at dietary levels is safe.
Should I stop fisetin while breastfeeding?
Yes, until safety data emerge. Dietary fisetin from fruits is safe; supplement doses have not been characterised for milk transfer or infant safety.
Can I take fisetin while trying to conceive?
Discontinue at least one full menstrual cycle before attempted conception. The rationale is precaution during the developmentally critical peri-conceptional window.
Does fisetin affect fertility?
Unstudied in humans. Preclinical data suggest complex effects on ovarian and endometrial tissue (1). Neither pro-fertility nor anti-fertility effects have been demonstrated in a clinical trial.
Is fisetin listed in any pregnancy category?
Fisetin is a dietary supplement, not a regulated pharmaceutical, and is not assigned a formal pregnancy category (A, B, C, D, X). This absence is not reassuring — it reflects the lack of clinical trial data.
References
1. Wang C, Kim SY, Lee W, et al. Fisetin as a senotherapeutic compound in women’s reproductive health: evidence from in vitro to clinical studies. Antioxidants (Basel). 2025;14(9):1084. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12899922/
2. Kimira Y, Osada A, Kimura M, et al. Contents of a bioactive flavonoid fisetin in fruits and vegetables used in the average Japanese diet. J Nutr Sci Vitaminol. 2019;65(5):443-447. https://pubmed.ncbi.nlm.nih.gov/31666481/
3. Vanhees K, Vonhögen IG, van Schooten FJ, Godschalk RW. You are what you eat, and so are your children: the impact of micronutrients on the epigenetic programming of offspring. Cell Mol Life Sci. 2014;71(2):271-285. https://pubmed.ncbi.nlm.nih.gov/23934442/
4. Wang N, Wang L, Yang J, et al. Fisetin regulates astrocyte migration and proliferation in vitro. Int J Mol Med. 2019;44(3):771-780. https://pubmed.ncbi.nlm.nih.gov/31257464/
5. Grynkiewicz G, Demchuk OM. New perspectives for fisetin. Front Chem. 2019;7:697. https://pmc.ncbi.nlm.nih.gov/articles/PMC6817492/
6. Sanapo L, Miller EC, Grewal J, et al. The effect of pregnancy on senescence: implications for maternal and fetal health. Cells. 2023;12(8):1146. https://pmc.ncbi.nlm.nih.gov/articles/PMC10137146/
7. Ross AC, Manson JE, Abrams SA, et al. The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: what clinicians need to know. J Clin Endocrinol Metab. 2011;96(1):53-58. https://pubmed.ncbi.nlm.nih.gov/21118827/
8. Khan N, Syed DN, Ahmad N, Mukhtar H. Fisetin: a dietary antioxidant for health promotion. Antioxid Redox Signal. 2013;19(2):151-162. https://pmc.ncbi.nlm.nih.gov/articles/PMC3689181/