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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your healthcare provider before using herbs, especially if you are pregnant, nursing, taking medications, or have a medical condition.
How does Lawsonia inermis work as a dye and medicinal agent?
The primary active compound, lawsone (2-hydroxy-1,4-naphthoquinone), is responsible for the dyeing properties. It binds covalently to keratin proteins in hair and skin, creating a stable reddish-brown stain. Medicinally, lawsone, along with tannins and flavonoids, provides antimicrobial and anti-inflammatory effects by disrupting microbial cell walls and scavenging free radicals. Evidence level: C/Traditional.
Is Lawsonia inermis safe to use during pregnancy?
Topical application of pure, natural henna is generally considered safe during pregnancy and is often used for belly art. However, internal use is contraindicated as it may stimulate uterine contractions. Pregnant women must strictly avoid 'black henna' products, which often contain paraphenylenediamine (PPD), a toxic chemical linked to severe allergic reactions. Evidence level: C.
What is the recommended dosage for Lawsonia inermis?
For topical use on hair or skin conditions, a paste made from dried leaf powder and water is applied for 1 to 6 hours. For internal use, such as for headache relief, a traditional adult dosage involves brewing 2-3 grams of dried leaf into a tea. Internal use requires caution and should be avoided by those with specific enzyme deficiencies. Evidence level: Traditional.
Does Lawsonia inermis interact with medications?
Pure Lawsonia inermis has no widely documented severe drug interactions. However, products labeled 'black henna' frequently contain paraphenylenediamine (PPD), which can cause severe allergic contact dermatitis and may cross-react with certain medications, including sulfonamides and benzocaine. Always verify product purity to avoid PPD-related complications. Evidence level: C.
Who should avoid using Lawsonia inermis?
Individuals with Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency should strictly avoid henna, both topically and internally. Exposure in these individuals can trigger acute hemolytic anemia, a potentially life-threatening condition where red blood cells are destroyed. Parents should screen children for this deficiency before applying henna skin decorations. Evidence level: C.
PubMed-compiled information sheet
This sheet was compiled from PubMed (NIH) abstracts using AI assistance. Every factual claim is cited to a real PubMed article (see the source list). It has not yet been human-reviewed — confirm with a healthcare provider before use.
Compiled from 30 PubMed articles · model: gemma4:31b
Summary
Lawsonia inermis, commonly known as henna, is a member of the Lythraceae family used for cosmetic dyeing and various medicinal purposes [PMID: 38010396, 24886774].
Background
Henna is a plant that thrives in subtropical and tropical climates, with bioactive compounds found in its stem, bark, roots, flowers, and seeds [PMID: 38213476, 38010396].
Traditional uses
Traditional uses include treating ulcers, bronchitis, lumbago, hemicrania, leukoderma, scabies, boils, ophthalmic disorders, hair loss, jaundice [PMID: 38010396], as well as liver and digestive disorders, diabetic foot disorders, and protecting against fungal pathogens and lice [PMID: 24886774].
Active compounds
Key compounds include naphthaquinones (specifically lawsone/hennotannic acid), flavonoids, coumarins, triterpenoids, steroids, xanthones, polyphenols, fatty acids, alkaloids, quinones, tannins, leucocyandin, epicatechin, catechin, and quercetin [PMID: 24886774, 38010396, 39081702]. The terpene β-ionone is responsible for the scent of flower essential oil [PMID: 24886774].
Mechanism of action
Lawsone exhibits potential antioxidant, anti-inflammatory, antimicrobial, and antitumor properties, including the inhibition of pro-inflammatory cytokine production and induction of cell cycle inhibition and programmed cell death in cancer cells [PMID: 39081702].
Clinical evidence
Evidence BChronic Sciatica
A topical formulation of henna (aqueous extract in sesame oil) significantly decreased mean pain intensity (VAS) compared to sesame oil and placebo [PMID: 37105368]
Evidence DWound Healing
L. inermis-extracted oil demonstrated an efficient wound healing effect in a rat model, showing full reepithelialization and organized collagen fibers [PMID: 31466077]
Evidence DHepatotoxicity
Methanolic extract of L. inermis leaves showed dose-dependent hepatoprotective effects against carbon tetrachloride-induced toxicity in rats [PMID: 27069719]
Evidence DAndrogenetic Alopecia
Topical application of L. inermis promoted new hair growth in a mouse model [PMID: 31852654]
Evidence DTuberculosis
In vitro and in vivo studies showed inhibition of Mycobacterium tuberculosis and resolution of experimental tuberculosis in guinea pigs and mice [PMID: 2125156]
Safety & adverse effects
Pure red henna is generally safe with rare contact allergy [PMID: 23782354]. However, 'black henna' containing para-phenylenediamine (PPD) is a potent allergen causing severe contact dermatitis, blistering, and chemical leucoderma (depigmentation) [PMID: 32941558, 32926447, 21063517, 11763395]. In children with glucose-6-phosphate dehydrogenase deficiency, topical application may cause life-threatening haemolysis [PMID: 23782354].
Evidence summary
Evidence consists primarily of traditional use reports, in vitro studies, and animal models (Level D), with a few small-scale randomized controlled trials (Level B) for specific conditions like sciatica.
PubMed sources
1.PMID: 24886774 (2014) — Lawsonia inermis L. (henna): ethnobotanical, phytochemical and pharmacological aspects. · Journal of ethnopharmacology
No direct government monograph is available for this herb. The content below is AI-generated and has not been verified against an authoritative government source. Use the search links to check official sources before relying on this information.
— Side-effects of henna and semi-permanent 'black henna' tattoos: a full review.
· Contact dermatitis
7.PMID: 38213476 (2023) — Back to nature: henna extracts from nanotech to environmental biotechnology - a review. · Biotechnologia
8.PMID: 37105368 (2023) — The effect of a topical formulation from Lawsonia inermis L. (henna) on pain intensity in patients with chronic sciatica: A randomized double-blind clinical trial. · Journal of ethnopharmacology
9.PMID: 27069719 (2016) — Effects of Lawsonia inermis L. (Henna) leaves' methanolic extract on carbon tetrachloride-induced hepatotoxicity in rats. · Journal of intercultural ethnopharmacology
10.PMID: 11763395 (2001) — Hypopigmentation after non-permanent henna tattoo. · Journal of the European Academy of Dermatology and Venereology : JEADV
11.PMID: 21063517 (2010) — Chemical leucoderma: Indian scenario, prognosis, and treatment. · Indian journal of dermatology
12.PMID: 39081702 (2024) — Lawsone Unleashed: A Comprehensive Review on Chemistry, Biosynthesis, and Therapeutic Potentials. · Drug design, development and therapy
13.PMID: 31852654 (2019) — [Therapeutic effect of Impatiens balsamina, Lawsonia inermis L. and Henna on androgenetic alopecia in mice]. · Nan fang yi ke da xue xue bao = Journal of Southern Medical University