Rayon, usually sold as viscose, is a semi-synthetic fiber. It starts from a natural material, wood pulp or other cellulose, but it only becomes a usable fiber after a chemical process dissolves and reforms it. That is why it sits in a gray zone: not a true natural fiber like cotton, and not a fully synthetic one like polyester. In period products, rayon is valued for one trait above all: it is extremely absorbent.
Why rayon shows up in tampons
Most conventional tampons are made of cotton, rayon, or a blend of the two. Rayon's high absorbency lets a smaller tampon hold more fluid, which is convenient. The trade-off is what that absorbency was historically associated with.
The toxic shock syndrome connection
Rayon's most important safety story is its link to toxic shock syndrome. The early-1980s TSS outbreak was traced to a specific super-absorbent tampon that used synthetic materials, including high-absorbency forms of rayon. The product was withdrawn, super-absorbent materials were reformulated, and TSS rates dropped. Modern viscose rayon used in tampons is considered safe by health researchers today, but the episode is why fiber type and absorbency are still treated as linked safety questions, and why 100% cotton is often preferred for the cleanest profile.
Rayon vs cotton: what it means for you
The practical differences:
- Processing chemistry. Rayon is chemically processed from pulp, so it carries more manufacturing inputs than mechanically spun cotton. A 100% cotton core is the simpler, cleaner option.
- Absorbency and TSS. Because high absorbency is part of the historical TSS picture, matching absorbency to your flow matters regardless of fiber, but a pure cotton core avoids the specific synthetic-rayon association.
- Labeling. A box listing 'cotton and rayon' or just 'rayon/viscose' is a step below '100% cotton' on R3's fiber scale. Conventional drugstore tampons are frequently cotton-rayon blends.
How R3 reads rayon
In R3's tampon scoring, the absorbent core fiber is a safety signal. A 100% cotton core, ideally organic, scores highest. A cotton-rayon blend scores in the middle, and a predominantly rayon or viscose core scores lower, because it is the most processed option and carries the historical TSS association. Rayon is not banned or acutely dangerous in modern tampons, but when a cleaner pure-cotton option exists at a similar price, it is the better default.
