What Is Henna Hair Dye? | Plant-Based Color, FDA Rules

Henna hair dye is a plant-based coloring made from the dried leaves of the henna plant, approved by the FDA for coloring hair only.

If you’re considering henna hair dye, you’re looking at one of the oldest hair-coloring methods in human history—one that comes with a specific set of rules and limits that differ from conventional chemical dyes. Here’s what henna actually is, how the FDA regulates it, and how to use it safely on your hair.

What Exactly Is Henna?

Henna is a coloring made from a plant, specifically the dried leaf and petiole of Lawsonia alba Lam. (Lawsonia inermis L.), per the FDA’s regulatory definition. The leaves are ground into a powder and mixed with a liquid—often water, tea, or an acidic solution like lemon juice—to create a paste that stains hair and skin a reddish-brown tone.

The staining compound in henna binds to the protein in your hair shaft, which is why the color gradually fades rather than washing out quickly. This binding also explains why henna results are semi-permanent to permanent, depending on how often you apply it and your hair’s porosity.

How Does the FDA Regulate Henna?

In the United States, henna has an unusual regulatory status. The FDA’s color additive listing identifies henna as “Permanently listed, exempt from certification” with one critical restriction: it’s approved for coloring hair but not for eyelashes, eyebrows, or the eye area.

This distinction matters because many people associate henna with body art. The FDA explicitly states henna is not approved for direct application to the skin, which includes mehndi or body-decorating use. If you see products marketed for skin application in the U.S., they’re operating outside the FDA’s approved use, which is why regulation and careful product selection matter.

How to Use Henna Hair Dye Safely

The FDA’s consumer guidance for hair dyes applies to henna, and it’s worth following every time. Start with a patch test before each application—apply a tiny amount to the inside of your elbow or behind your ear, leave it for two days, and skip the henna if any rash develops. Some people develop sensitivity to henna even after years of use, so testing every time is the rule, not the exception.

When you’re ready to apply, protect yourself and follow the package directions exactly. Wear gloves during application, rinse your scalp thoroughly afterward, keep the product away from children, and never mix henna with other hair-dye products. Leaving the dye on longer than directed doesn’t produce a more intense color—it just increases the chance of skin irritation.

One note on timing: if you’ve recently used chemical dye, some henna brands advise waiting about a month before applying their product. That guidance varies by brand, so check the label of whatever henna you choose.

What to Know Before Buying Henna

Not all henna products are chemically identical. EU scientific opinions on henna note that safety assessments were based on specific batches and formulations—one review found insufficient information to assess henna as a hair dye generally, while another deemed specific batches and formulations adequate. That variability means ingredient quality and sourcing differ meaningfully across brands, and it’s worth choosing a product with a clear ingredient list.

You should also be aware of “black henna,” which the FDA’s fact sheet covers separately because it involves different products and safety concerns. Plain henna is a reddish-brown plant dye; black henna often contains additional ingredients and carries different risks. If a product labeled henna promises jet-black results, it’s likely not pure henna.

Because henna products can be adulterated, choosing a reputable brand and reading the ingredient list carefully isn’t just a preference—it’s a safety step. For a vetted starting point, our roundup of 100 natural henna hair dyes can help you compare clean options side by side.

For reference, here’s a quick snapshot of what henna is and isn’t under FDA rules:

The bottom line: henna is a legitimate, plant-based hair color with a long history of use, but its regulatory approval in the U.S. is specific to hair. Use it for that purpose, test before each application, and choose products from brands that are transparent about their ingredients.