Natural Vegetable Hair Dye
Many people eager to avoid exposure to the chemicals in synthetic hair dyes are experimenting with natural vegetable hair dye. Natural vegetable hair dyes do have limitations in terms of their effectiveness, but for the right person, they can be a great alternative.
The Case Against Synthetic Dyes
Although followup studies didn't corroborate the research, a 2005 study did link synthetic hair dye use by pregnant women to the childhood cancer neuroblastoma. Studies also suggest a link between long-term synthetic hair dye use and an increase in the risk of bladder cancer.
The Limitations of Natural Dyes
Because natural dyes don't contain hydrogen peroxide, which is used to help soften the shaft of the hair to accept dye more deeply and permanently, natural dyes that put color on hair wash out after as little as three weeks. The lack of peroxide, combined with the fact that gray hair is particularly dye resistant, means that natural hair dyes aren't effective at even temporarily dying hair that is more than 20 percent gray.
Dying Versus Enhancing
Using natural hair dyes to make a huge color shift is only possible if you're going from light to dark. If you're a blonde, you can use henna to dye your hair red, auburn, or brown. If you already have dark hair, henna will effectively only add red, auburn, or brown highlights to your hair, and you may need to apply the dye multiple times to see any alteration in your color at all. If you have blonde or brown hair you can use lemon, chamomile, and rhubarb mixtures to lighten your hair, but these mixtures don't have the ability to take you from brunette to platinum blonde the way that synthetic dyes do.
Get Professional Help
If you want to use a natural vegetable dye, but don't feel like you have the expertise to apply it evenly yourself, you can always bring it to your next salon appointment and ask your stylist to apply it for you.
Natural isn't always safe. It's possible to develop serious allergies to any vegetable product. Test the dye mixture you plan to use on a small patch of skin on your arm a couple of days before you plan to apply it to your scalp. If your skin doesn't react within 48 hours, you're probably safe.