Lady Fern (Athyrium filix-femina): Benefits, Dosage, Safety & Evidence

Frequently asked questions

How does Lady Fern work to kill parasites?

Lady Fern contains active compounds known as filicin and phloroglucinol derivatives. These constituents function as anthelmintics by paralyzing intestinal worms, particularly tapeworms, which prevents them from attaching to the intestinal wall. Once the parasites are immobilized, they are expelled from the body. This mechanism is supported by traditional use and pharmacological studies on related fern species (Evidence Level C).

Is Lady Fern safe to take during pregnancy?

No, Lady Fern is considered unsafe during pregnancy and is strictly contraindicated. The herb contains compounds that can act as uterine stimulants, potentially causing miscarriage or premature labor. Furthermore, the active constituents, such as filicin, are toxic and may harm fetal development. Women who are breastfeeding should also avoid this herb due to potential toxicity to the infant and lack of safety data.

What is the recommended dosage for Lady Fern?

The traditional adult dosage for Lady Fern is 2 to 4 grams of the dried rhizome, prepared as a decoction and taken twice daily. This treatment is intended for short-term use only to expel parasites. Prolonged use or exceeding the recommended dosage significantly increases the risk of toxicity, including liver damage and visual disturbances. Medical supervision is strongly advised (Evidence Level C).

Does Lady Fern interact with other medications?

Due to its potential hepatotoxicity, Lady Fern may interact negatively with medications that stress the liver or are metabolized hepatically. It is contraindicated for individuals with heart disease, liver disease, or anemia, and may interfere with treatments for these conditions. Because clinical interaction studies are lacking, individuals taking prescription medications should consult a healthcare provider before use (Evidence Level C).

What are the side effects of taking Lady Fern?

Common side effects of Lady Fern include nausea and gastrointestinal discomfort. However, consuming excessive amounts or using the herb for prolonged periods can result in serious toxicity. Severe adverse effects include visual disturbances, such as blurred or yellow vision, and potential liver damage. Users experiencing these symptoms should discontinue use immediately and seek medical attention.

PubMed-compiled information sheet

This sheet was compiled from PubMed (NIH) abstracts using AI assistance. Every factual claim is cited to a real PubMed article (see the source list). It has not yet been human-reviewed — confirm with a healthcare provider before use.

Compiled from 21 PubMed articles · model: gemma4:31b

Summary

Lady Fern (Athyrium filix-femina) is a diverse genus of seedless vascular plants found in various forest ecosystems [PMID:29111475, PMID:21924813].

Background

Athyrium filix-femina is a fern species characterized by phenotypic plasticity and effective gene exchange via long-distance spore dispersal [PMID:21636465]. It is part of the Athyrium genus, which contains approximately 160-220 species [PMID:29111475].

Traditional uses

In Norway, the rhizomes of selected fern species, including those used as fodder (moldfôr), were historically collected, particularly in North Norwegian counties like Nordland and Troms during early spring fodder shortages [PMID:27600530].

Active compounds

Volatile organic compounds identified in Athyrium filix-femina include 2-phenylethanal and 1-octen-3-ol [PMID:21121267].

Clinical evidence

Evidence DCancer cell proliferation (Breast, Lung, Colon)

An ethanolic extract of a related species, Athyrium hohenackerianum, exhibited cytotoxic activity against HCT-116 colon cancer cells (IC50 123.90 μg/mL), causing cell arrest in the S phase and inducing apoptosis [PMID:35692581]

Safety & adverse effects

Athyrium filix-femina can accumulate heavy metals from the soil, including zinc, cadmium, copper, lead, and mercury; specifically, mercury content in the plants has been noted to present an ecological risk [PMID:27557601, PMID:28633101, PMID:40555890].

Evidence summary

The available evidence is primarily botanical, ecological, and environmental, with one in vitro study on a related species showing cytotoxic potential. There are no human clinical trials.

PubMed sources

1.PMID: 40555890 (2025) — Which trace elements are accumulated in fronds of the Athyrium filix-femina fern? a study from the Czech Republic. · Environmental monitoring and assessment
2.PMID: 21636465 (2007) — Patterns of variation of a common fern (Athyrium filix-femina; Woodsiaceae): population structure along and between altitudinal gradients. · American journal of botany
3.PMID: 27600530 (2016) — Fern rhizomes as fodder in Norway. · Journal of ethnobiology and ethnomedicine
4.PMID: 30538169 (2019) — Hydraulics Regulate Stomatal Responses to Changes in Leaf Water Status in the Fern Athyrium filix-femina. · Plant physiology
5.PMID: 29111475 (2018) — A total-evidence phylogeny of the lady fern genus Athyrium Roth (Athyriaceae) with a new infrageneric classification.

Lady Fern

Sources & Citations

Calculate a safe dose of Lady Fern