Can daily shampoo and personal care use affect thyroid hormones?

What's actually in it

Daily personal care products can expose people to bisphenol A (BPA), benzophenone-3, triclosan, and parabens. These chemicals can show up in shampoo, soap, sunscreen, cosmetics, and other products, depending on the formula.

The issue is repeated contact. A small amount from one product may be low, but many products used every day can raise total exposure.

What the research says

A 2026 study in Ecotoxicol Environ Saf analyzed NHANES data from 2,714 adults. The researchers compared urinary markers of personal-care-product chemicals with thyroid hormone measures.

They found that higher levels of several chemicals were linked with lower thyroid hormone measures, especially TT4. BPA, benzophenone-3, butyl paraben, ethyl paraben, methyl paraben, and propyl paraben were each linked with lower TT4 in the study.

The study also looked at mixtures. BPA, triclosan, ethyl paraben, and propyl paraben were important contributors to lower FT4 and TT4 in the mixture models. Some of the link was partly explained by markers of inflammation.

This was an association study, so it does not prove that one shampoo causes thyroid disease. It does support a practical habit: use fewer daily products when you can, and read labels for parabens, triclosan, benzophenone-3, and fragrance.