INDIANAPOLIS (CONSUMER REPORTS) — Store-bought hair dyes have been a go-to for decades, but they can sometimes come with unwanted side effects. Some users report skin irritation, itching, or even a burning sensation.

Now, a new Consumer Reports analysis is taking a closer look at what’s actually inside these products—and what it could mean for your health.

Consumer Reports tested 21 hair dye products, including permanent, semi-permanent, and even hair chalks, from major brands. The samples were analyzed by an independent lab for substances such as volatile organic compounds (VOCs), phthalates, and heavy metals. The results found that every product tested contained at least some contaminants, though leve...