Is Henna Bad for Your Hair? What Hairdressers Warn About, and What's True

The short answer: pure henna isn't bad for most hair. It's a single plant dye that gives long-lasting copper-red colour, and many people find it leaves their strands feeling fuller and shinier. The real drawbacks are practical: it's hard to remove or lighten later, it can feel drying on some hair, and plenty of products sold as "henna" aren't pure henna. Some people react to henna itself, which is what a patch test is for.

Is henna good or bad for your hair?

For most hair it isn't damaging, and it isn't a treatment either: it's a durable plant colour with a noticeable effect on how hair feels. Henna's dye binds to keratin, the protein hair is made of, and coats each strand. That's why the colour lasts and why fine hair often feels more substantial afterwards.

When people run into trouble, it's usually the routine or the product: a paste left to dry hard, strong lemon in the mix, rough rinsing, already damaged hair, or a "henna" that contained something else.

Why do hairdressers hate henna?

Most don't hate pure henna. What worries them is not knowing what's already on your hair. "Henna" on a box can mean pure leaf powder, a blend with metallic salts, or a product with hidden synthetic dyes, and some of those react badly with bleach or salon colour. Even pure henna is hard to lift: bleaching over it tends to reveal strong orange, and if indigo has been used too, green or blue tones can appear. So tell your colourist exactly what you've used, and ask for a strand test before any bleach, colour, perm or relaxer.

What are the downsides of henna?

• It's hard to undo. Henna grows out rather than washing out, and going lighter afterwards is difficult.
• It only goes one way. Pure henna gives copper to red. It can't lighten hair, and brown or black needs indigo too.
• It can feel drying. Dry, porous or bleached hair can feel stiff afterwards, especially if the paste dried hard. Keeping the paste moist and using conditioner usually help.
• It takes time. The paste rests 3–4 hours (ideally 8) and stays on at least 2 hours.
• It builds up. Repeated full-length applications make the lengths deeper and redder.
• Some people react to it. Allergy to pure henna is possible, so patch test 24–48 hours before first use.

Which henna should you avoid?

Avoid anything whose label doesn't tell you exactly what's in it. The red flags:

• "Black henna" or a promise of instant jet black. Some of these products contain PPD (p-phenylenediamine), a synthetic dye that can cause severe allergic reactions, especially in pastes for skin. If you've reacted to a "black henna" temporary tattoo, you may react strongly to hair dyes that contain PPD.
• Metallic salts or unnamed "dyes", which can react unpredictably with later salon colour.
• Several shade names for one "pure" henna. Pure henna comes in one colour, so extra shades mean extra ingredients.

Pure henna lists one ingredient, Lawsonia inermis leaf powder, with no PPD, ammonia or peroxide. Looking for black henna for hair without chemicals? No hair colour is chemical-free, and pure henna is never black; for black, apply henna and then indigo.

Which henna is better, black or brown?

Neither is pure henna. Both owe their shade to other plants or dyes. For brown, mix pure henna with indigo (see how to mix henna and indigo for brown hair); for black, apply henna and then indigo.

Is henna illegal in the US?

US rules allow henna only as a colour for hair. What they don't allow is henna on skin, as in body art, or on the eyebrows, eyelashes or anywhere around the eyes, and US labels must warn against use near the eyes and on a cut or abraded scalp. The products US authorities warn about are "black henna" pastes for skin, which often contain PPD, a synthetic dye that can cause severe allergic reactions. Spierb Henna Powder is sold for colouring hair only.

Can henna get into your bloodstream?

Henna is used on the outside of your hair, and most of the dye either binds to the hair or rinses away. Laboratory work on skin shows that a small amount of lawsone can pass through, so "none at all" isn't accurate either, but henna isn't used for any effect inside the body. Don't eat or drink it, keep it out of your eyes, and use it only on hair.

Is henna better than hair dye?

Neither is better for everyone; they do different jobs. Henna gives copper to red (and brown to black with indigo), pure henna contains no PPD, ammonia or peroxide, and it lasts until it grows out. Box and salon dyes can lighten hair and offer a much wider range of shades, including ash and blonde. If you want to go lighter or change shades often, box dye suits you better. If you're happy in the copper-to-black range, henna is worth a try.

How to use henna without trouble

1. Check the label. One ingredient, Lawsonia inermis leaf, and nothing else.
2. Patch test 24–48 hours before first use, with the mix you plan to use. Don't go ahead if the skin burns, swells, blisters or turns red, or if it itches and the itch doesn't settle.
3. Strand test a hidden lock to see the colour first.
4. Keep the paste moist, rinse gently with water, and condition if your hair feels rough.
5. Tell your colourist before any salon service.

The full method, and what not to do afterwards, is in how to use henna powder for hair.

Frequently Asked Questions

What is the safest henna to use?

Look for a single ingredient, Lawsonia inermis leaf powder, with no PPD, dyes or metallic salts, and patch test it before first use. No hair colour suits everyone, henna included.

Is henna safer than hair dye?

Pure henna contains no PPD, ammonia or peroxide, but that doesn't make it reaction-free: some people react to henna itself, so patch test either way.

Can henna cause hair to fall out?

You may see more hair in the sink after henna: the thick paste can release hairs that had already shed naturally, all at once as it rinses out, and rough rinsing can break fragile strands. That can be loosened shed hair and breakage rather than hair lost from the root. Significant new shedding is a different matter, and hair loss has many causes: if you're losing hair suddenly or in patches, see a doctor or pharmacist.

Does henna make hair thicker?

No, not in the sense of more hair. It coats each strand, so existing hair can feel more substantial and look fuller, but it doesn't add hairs or change how your hair grows.

Can henna increase hair growth?

No. Henna is a hair colour. It doesn't make hair grow faster or longer.

What is the problem with henna?

Mostly that it's permanent and hard to lighten, and that many products called "henna" aren't pure. Choose a single-ingredient henna, strand test, and tell your colourist.

Why shouldn't we apply henna on hair?

Skip it if you're allergic to henna, if your patch test reacts, if your scalp is cut or irritated, or if you plan to go lighter soon. Our page on itchy scalp after henna covers who should avoid it.

How can I cover grey hair without dye?

Henna and indigo are plant dyes: henna alone turns greys copper, and with indigo they can go brown or black. Our guide to covering grey hair with henna and indigo explains the options.