Polypodium Leucotomos

Polypodium leucotomos · Phlebodium aureum · Fernblock

Snapshot

Indications	Contraindications
Sunburn resistance¹ Polymorphic light eruption² Actinic keratosis adjunct^3–5 Melasma adjunct⁶ Vitiligo adjunct⁷ Xeroderma pigmentosum support⁸	Under 18 years⁹ Pregnancy or lactation⁹

Polypodium leucotomos (also Phlebodium aureum) is a tropical fern whose standardized aqueous extract, marketed as Fernblock, acts as an antioxidant that limits ultraviolet-induced oxidative and deoxyribonucleic acid (DNA) damage^{10, 11}. People take it by mouth for photoprotection, which drives its other uses: resistance to sunburn, polymorphic light eruption, adjunct care in actinic keratosis, and pigmentary disorders such as melasma and vitiligo^{12, 13}. The typical patient is fair-skinned, photosensitive, or heavily sun-exposed.

A randomized trial in healthy adults found a higher ultraviolet dose was needed to cause skin redness, with fewer sunburn episodes. Systematic reviews place it among the better-supported oral photoprotectants, limited by small, short studies. In vitiligo, benefit is described alongside phototherapy. A 2025 systematic review of antioxidants in melasma reported mixed results for the extract, with promise when combined with other treatments¹⁴. Products are mostly capsules, with 28 products listing Polypodium leucotomos; see Form comparison.

Reviewed studies report good tolerability, with mild gastrointestinal complaints and itching in few patients¹⁵. Seven of 10 United States (US) product labels ask pregnant or nursing users to consult a physician before use⁹.

Last updated October 16, 2026. Read how we make monographs.

In the full monograph

51 sources, 39 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources