Are Your Leggings Messing with Your Hormones?

What’s in your leggings?

Most conventional leggings are made from blends of synthetic fibres such as polyester, nylon and elastane (Spandex or Lycra). While these fibres offer stretch, durability and sweat-wicking properties, they also bring with them a cocktail of chemicals including:

Microplastics: These tiny plastic fibres shed during wear and washing, polluting waterways and harming marine life. They can enter the human body via skin contact, inhalation or ingestion, triggering inflammation, hormone disruption, oxidative stress, and long-term health effects as they accumulate in tissues such as the brain.

Phthalates: Often used to soften plastics and improve fabric flexibility, phthalates are known endocrine disruptors that may interfere with hormone balance, fertility, and foetal development. 

PFAS (per- and polyfluoroalkyl substances): These “forever chemicals” are added for water, oil or stain-resistance. PFAS accumulate in the body and have been linked to immune suppression, thyroid dysfunction, reproductive harm and cancer.

Formaldehyde: Used to reduce wrinkles and prevent shrinkage, formaldehyde is a known skin irritant and classified as a human carcinogen by health authorities.

Azo dyes: Commonly used to colour synthetic fabrics, some azo dyes can break down into aromatic amines which are compounds associated with an increased risk of cancer.

Because leggings are tight-fitting and worn directly against the skin – often in the warm, damp environment of a workout – they can increase chemical absorption through the skin. For women, this can be particularly concerning when leggings are in close contact with sensitive areas, potentially disrupting the vaginal microbiome or affecting hormone regulation over time.