Is spandex or elastane in clothing harmful to health?

Spandex (also marketed as elastane or Lycra) is a polyurethane-based synthetic fiber used in small percentages (2-20%) in stretch clothing. It is produced using diisocyanates, which are potent respiratory sensitizers in their raw form, though the finished fiber is considered more stable. The primary health concerns with spandex relate to its synthetic nature and the chemical treatments often applied to garments containing it.

Spandex degrades over time with heat, sweat, and washing, gradually losing elasticity and potentially releasing breakdown products. When blended with natural fibers, spandex prevents the garment from being fully biodegradable. Even a small percentage of spandex means the garment will not decompose naturally and will contribute microplastic fragments as the spandex component degrades.

For activewear that requires stretch, some brands achieve sufficient elasticity through fabric construction techniques like knit patterns rather than spandex content. Tencel jersey knit provides four-way stretch without any synthetic fiber. Brands on ONDU like Tripulse demonstrate that comfortable, stretchy activewear is achievable with 100% natural or plant-based fibers.