Henna (Lawsonia inermis) is a natural dye made from powdered leaves of a shrub native to North Africa and South Asia. For over 3,000 years it has colored hair, skin, and nails—and, when used correctly, it can add shine, boost hair grip and volume, calm a flaky scalp, and create rich copper-to-deep auburn tones without ammonia or peroxide. Its principal pigment, lawsone (2-hydroxy-1,4-naphthoquinone), binds to keratin and forms a stain that can last weeks on hair and several days on skin. Pure henna is reddish; “neutral henna” is usually cassia, and “black henna” often contains para-phenylenediamine (PPD), a strong allergen to avoid. This guide explains what henna can realistically do, how to select quality powder, proven mix-and-apply methods, common variables that change color and durability, safety dos and don’ts (including G6PD deficiency and PPD allergy), and what modern studies and cosmetic assessments actually say about efficacy and risk.
Quick Facts
- Pure henna (Lawsonia inermis) deposits stable copper–auburn tones, conditions hair, and may help a flaky scalp.
- “Black henna” products may contain PPD; avoid them to prevent allergic contact dermatitis and long-term sensitization.
- Typical hair application uses 100–300 g powder mixed 1:2–1:3 with liquid, left on 1–4 h; skin designs stain in 4–48 h.
- Do not use henna on infants or anyone with known G6PD deficiency; risk of hemolysis has been reported after topical use.
- Pregnant or breastfeeding individuals should prefer pure, additive-free henna or postpone use after medical advice.
Table of Contents
- What is henna?
- Benefits and what to expect
- How to use it for hair and skin
- Dosage and mixing ratios that work
- Safety, side effects, who should avoid
- Evidence: what studies show
What is henna?
Henna is a finely milled powder from the dried leaves of Lawsonia inermis. When hydrated, leaf pigments—chiefly lawsone—migrate from the paste and covalently bind to keratin in hair and skin. This bond resists shampoo and water, explaining henna’s reputation for long-lasting color and the characteristic “oxidation” shift from bright orange to deeper copper-brown over 24–48 hours.
Types you’ll see on labels
- Pure henna (red henna). 100% Lawsonia inermis leaf. Yields copper through auburn on hair; orange-brown on skin.
- Neutral henna. Usually Cassia obovata/italica (cassia). Adds gloss and slight gold on light hair; minimal color on dark hair.
- Indigo powder. From Indigofera tinctoria; used with henna for brown to black hair shades (two-step or mixed).
- “Black henna.” Often a marketing term for products adulterated with PPD or azo dyes to create an instant black stain on skin. Avoid these.
How lawsone staining works (plain-English version)
Lawsone molecules leave the paste as it “releases dye,” then diffuse into the outer keratin layers. There, they form stable bonds, creating a translucent stain. On hair, the transparent red-orange overlay mixes optically with your natural melanin—so results vary by starting color. On skin, the stain is strongest where keratin is thickest (palms/soles) and fades as cells shed.
Why people choose henna
- Permanent to demi-permanent color without developers.
- Improved hair feel for many users: more “grip,” fuller ponytail, smoother cuticle with continued use.
- Scalp comfort: some find less flaking or itching with pure, additive-free pastes compared with synthetic dyes.
Quality cues
Look for harvest year, sift grade (fine sift for hair), region (Rajasthan, Yemeni, Sudanese), and proof of no PPD/metal salts. Fresh henna is olive-green to brownish-green, not gray or tan. A faint hay-or-tea aroma is normal; a harsh chemical smell isn’t.
Benefits and what to expect
1) Hair coloring with conditioning
Pure henna deposits color and can make hair feel thicker by adding weight to the cuticle surface. Expect:
- On light blond to light brown: copper to copper-auburn in one application; deeper red with repeats.
- On medium to dark brown: warm red “glow” in sunlight; deeper auburn with multiple applications.
- On very dark hair: subtle warmth only; consider henna-indigo layering for brunette/black shades.
Henna does not lift pigment, so it won’t make hair lighter. Instead, it tints by overlaying translucent dye. Many users report reduced frizz and improved shine after 2–3 full-head applications, likely from cuticle smoothing and hydrophobic surface effects.
2) Scalp comfort
Henna pastes are mildly acidic and can be soothing for some itchy, flaky scalps. A clean, additive-free mix avoids common irritants found in some boxed dyes. Users often pair henna with antifungal-friendly routines (regular washing, gentle scalp massage) for best results.
3) Durability
On hair, henna is wash-resistant and photo-stable. Initial orange tones deepen over 1–2 days as the stain oxidizes. On skin, peak stain develops by 24–48 hours, darkest on palms. On nails, henna can produce an even, protective orange-red stain that grows out with the nail plate.
4) Custom shades
- Copper → auburn: Adjust dye time, paste acidity, and application time.
- Brown → black: Combine with indigo (henna first, then indigo for jet black; or blend for browns).
- Golden gloss: Use cassia on light hair or mix small amounts of henna for strawberry-gold.
What not to expect
- No lightening or cool ash tones from henna alone.
- No instant jet-black skin stain with pure henna (that requires unsafe PPD).
- No reversal with bleach in one step; henna’s stain resists harsh chemicals and may require slow color correction.
Practical expectation setting
First application results vary with hair porosity and starting color. Do a strand test with your exact mix and timing before committing to a full head. With each repeat, color builds depth and longevity.
How to use it for hair and skin
Step-by-step: hair application (pure henna)
- Choose your amount. Short hair ~100 g, shoulder-length 200 g, mid-back 300 g. Thick/curly hair may need more.
- Mix paste. Add warm distilled water (or a mild acidic liquid like lemon-water or hibiscus tea) to a yogurt-like thickness (roughly 1:2–1:3 powder\:liquid by weight). Optional: 1–2 tsp sugar for slip; a few drops of a bland oil if hair is very coarse.
- Dye release. Cover and rest 4–12 h at room temp (some fresh powders release in 1–4 h). A brownish film and orange stain on a paper strip signal readiness.
- Prep hair. Wash with a non-coating shampoo; no conditioner. Towel dry to damp. Protect skin with balm along the hairline and ears; wear gloves.
- Apply generously. Section hair; coat from roots to tips.
- Process. Cover with wrap/cap to prevent drying. Leave 1–4 h (more time = richer stain). Warmth speeds things.
- Rinse. Rinse thoroughly with water; postpone shampoo 24–48 h to let color oxidize and deepen.
- Oxidize. Expect bright copper day 1; deeper auburn by day 2.
Henna + indigo for browns and black
- Two-step black: First do a full henna application (1–4 h), rinse, then apply fresh indigo paste (1:1 powder\:water) for 45–90 min.
- One-step brunette: Mix henna and indigo pastes just before application (common ratios by weight: H\:I = 2:1 for warm brown; 1:1 for brunette; 1:2 for dark brunette). Process 1–3 h.
Skin designs (mehndi)
- Sifted henna + lemon juice + sugar makes a smooth, clingy paste. Essential oils rich in monoterpenes (e.g., tea tree, cajeput, lavender) can improve stain; keep totals modest (e.g., 3–6% of paste by weight) and patch test.
- Clean, dry skin; avoid lotions. Apply with cone or fine tip. Keep paste on 4–12 h, keep warm and slightly moist (seal with sugar-lemon syrup). Scrape off; avoid water 12–24 h. Peak stain appears 24–48 h later.
- Pure henna yields orange→rust stains—never jet-black. Avoid any “instant black” product.
Nails
Degrease nails; apply thick paste; wrap tips to keep moist. Leave 2–4 h. Stain grows out with the nail. Useful when polish is contraindicated or for cultural practices.
Troubleshooting
- Weak color: Paste too thin, dried out on hair/skin, insufficient time, or stale powder. Increase dye release time slightly, maintain moisture, and extend processing.
- Grainy paste / difficult rinse: Use finer sift; add a bit more liquid and time for the paste to hydrate.
- Scalp itch: Remove essential oils, reduce acidity, or shorten time. Rinse thoroughly.
- Green sheen on gray hair: Normal at first; oxidizes to copper-auburn within 48 h. If not, warm the mix and extend time.
Dosage and mixing ratios that work
Because henna is topical, “dosage” refers to grams of powder, liquid ratios, and contact times.
Hair amounts (by length and density)
- Pixie/very short: 50–100 g
- Short bob: 100–150 g
- Shoulder length: 200 g
- Mid-back: 300 g (very thick hair may use 350–400 g)
Liquid ratio
- Start at 1:2 powder\:liquid by weight (e.g., 100 g powder + 200 g warm water). Adjust to a yogurt-like body that doesn’t drip.
- For indigo, stay near 1:1 with cool water; use immediately (indigo loses potency quickly).
Acid choice and strength
- A mild acid (e.g., 1–2 tsp lemon juice or apple cider vinegar per 100 g powder) can promote dye release and a deeper tone. Too much acid can dry hair; balance with plain water or brew tea instead.
- For delicate scalps, use neutral pH (just warm water) and longer, gentler dye release.
Processing time
- Hair: 1–4 h; thicker/coarser hair benefits from the long end.
- Indigo step: 45–90 min.
- Skin designs: 4–12 h on skin, then avoid water 12–24 h.
Frequency
- Roots/gray coverage: Every 3–6 weeks.
- Gloss/conditioning: Mix 10–30 g henna into 100–300 g conditioner; apply 20–30 min on clean hair. (Test first; conditioner can buffer color.)
Patch testing
- Place a small dab of final paste on the inner forearm for 24–48 h. Watch for redness, itch, or blistering. If using essential oils, patch test with the oils included.
Storage
- Powder: cool, dark, airtight; best within 1–2 years of harvest.
- Paste: freeze in portions up to 3–6 months; thaw overnight.
Color math (quick reference)
- More time/heat/acidity → deeper, warmer stain.
- More indigo → cooler brown to black.
- More cassia → lighter, golden tones (limited on dark hair).
Safety, side effects, who should avoid
Pure henna versus “black henna”
- Pure henna allergies are uncommon but possible.
- “Black henna” often contains PPD, a strong sensitizer linked to severe allergic contact dermatitis, blistering, and lifelong dye sensitivity. Avoid any product promising an instant jet-black skin stain.
G6PD deficiency
Topical henna has been associated with hemolysis in individuals (especially infants and children) with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Families with known or suspected G6PD deficiency should avoid henna, including skin designs. If jaundice, dark urine, pallor, or lethargy appear after exposure—especially in children—seek urgent care.
Who should avoid or take extra care
- Infants and young children: Avoid henna on skin or hair.
- Known G6PD deficiency (any age): Avoid.
- Pregnancy/breastfeeding: Prefer truly additive-free pure henna if proceeding; when in doubt, defer or consult a clinician.
- History of dye allergies or eczema: Patch test every new batch. Strictly avoid any product listing PPD, “coal tar dyes,” or colorants other than plant powders.
- Broken/irritated skin or scalp: Wait until healed.
Possible side effects (usually mild with pure henna)
- Dryness or rough feel if mixes are overly acidic or left on very long; correct by reducing acid/time and conditioning post-rinse.
- Itch or redness from essential oils; remove EO or switch to gentler oils.
- Rare contact dermatitis to henna itself.
Interactions and salon chemistry notes
- Metallic salt-containing “compound hennas” can react with peroxide dyes or perms, causing unpredictable color/texture. Use 100% plant powders only.
- After henna, wait at least 1–2 weeks before lightening; do a strand test.
- Keratin treatments and heavy silicones can reduce dye uptake; clarify first.
Emergency signs after exposure
- For suspected PPD reactions: rapid swelling, burning, blistering—seek medical care.
- For suspected hemolysis (G6PD): dark cola-colored urine, jaundice, extreme fatigue, rapid breathing. Seek emergency care promptly.
Evidence: what studies show
Mechanism and skin biology
Experimental work shows lawsone can activate the aryl hydrocarbon receptor (AhR) in skin models, influencing barrier function and inflammation. In acute irritation models, a lawsone-containing cream reduced signs of irritation, while other contexts suggest delayed wound closure—highlighting that context and concentration matter.
Cosmetic safety assessments
Regulatory reviews assessing henna as a hair dye conclude that mixtures such as 100 g powder + 300 mL water applied for 15 min–2 h are acceptable for consumers when lawsone content is controlled and the product is used as intended on hair. These opinions do not endorse “black henna” for body art, and they call for ongoing evaluation of lawsone’s genotoxicity and the safety of non-leaf extracts.
Allergy and contact dermatitis
Dermatology literature links severe reactions primarily to PPD—present in many “black henna” temporary tattoos and some hair dyes. Reactions range from eczematous plaques to blistering that may require grafting, and sensitization can persist for life, affecting future hair-dye choices and some occupations.
G6PD-related hemolysis
Multiple case reports describe hemolysis after topical henna in G6PD-deficient infants, children, and adults. While rare on a population basis, the severity of outcomes (including severe anemia and hyperbilirubinemia) supports a precautionary approach: avoid henna in known or suspected G6PD deficiency and never use on infants.
Clinical odds and ends
Pilot and regional studies explore henna blends for cervicitis and other indications; these are early-stage and not a basis for self-treatment. For hair and skin coloring, the most relevant human-facing data concern application parameters, allergen avoidance, and patch testing, rather than therapeutic claims.
Bottom line from the evidence
- For hair color and conditioning, pure henna is a viable option when used with sound technique.
- For skin designs, only use pure henna prepared safely; avoid PPD-adulterated products.
- For vulnerable groups (infants, G6PD deficiency), do not use.
- Keep expectations grounded: henna excels at warm tones, durability, and shine, not cool or lifting colors.
References
- The Henna pigment Lawsone activates the Aryl Hydrocarbon Receptor and impacts skin homeostasis (2019)
- Opinion on Lawsonia Inermis (Henna) C169 – Corrigendum (2013) (Guideline)
- Allergic Contact Dermatitis Reaction to Permanent Tattoo Containing Paraphenylenediamine: A Case Report (2024)
- Henna-Induced Intravascular Hemolysis in a Glucose-6-Phosphate Dehydrogenase-Deficient Ghanaian Female Child with Full Defect (2025)
- Quantification of Lawsone and p‐Phenylenediamine in Natural Henna (2025)
Disclaimer
This guide is educational and does not replace personalized medical advice. Do not use henna on infants or anyone with known or suspected G6PD deficiency. Avoid “black henna” and any henna product listing PPD or synthetic dyes. If you have a history of dye allergies, eczema, or sensitive skin, perform a patch test before each use and consult a qualified healthcare professional. Seek urgent care for signs of a severe reaction (rapid swelling, blistering, trouble breathing) or for dark urine/jaundice after henna exposure.
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