Henna – Lawsonia inermis

Detailed Description

Natural body art and plant-based dye for skin and hair.

Botanical Information

Henna is a tall shrub or small tree growing up to 8 meters. Its stem is smooth, densely branched, and bears numerous thorny twigs. Leaves are oppositely arranged, smooth, sessile, elliptic to lanceolate, tapering at the end, veined, 2-5 cm long, and 0.5-2 cm wide. Flowers have four sepals, with a 4 mm crimson calyx and 3 mm petal lobes. The fruit is a small brownish capsule (up to 8 mm in diameter) containing 32–49 seeds that open irregularly at four points.

Origin and Distribution

Henna is native to semi-arid and tropical areas of North Africa, West and South Asia, and northern Oceania. It is found in tropical savannas between 15° and 25° north latitude. Cultivation is widespread in India, Iran, Afghanistan, Pakistan, Morocco, Yemen, Somalia, Sudan, and Libya. It also grows throughout the Arabian Peninsula, South Asia, Southeast Asia, North, and East Africa.

Usage / Dosage

Since ancient Egypt, henna has been cherished for its mystical properties. It was used for coloring skin, wigs, and in mummification. Henna featured in ancient Carthage and on the eastern Mediterranean since the Bronze Age to beautify and adorn women's bodies. The earliest Middle Eastern reference connects henna to fertility and body beauty in legends about Baal and Anath, and wall paintings of young women from around 1700 BC depict its use.

Henna was popular among women in England’s 18th-century aesthetic movement. Artists like Dante Gabriel Rossetti, Evelyn De Morgan, and Frederick Sandys depicted bohemian women with henna-red hair, while Gaston Bussière and French Impressionists followed suit. In the 19th century, it was glamorized in Europe by opera singer Adelina Patti and Parisian courtesan Cora Pearl, both of whom dyed their hair red, regardless of trends.

In Muslim countries, men traditionally dye their beards with henna (a custom attributed to the Prophet Muhammad). Across the Middle East, women use henna for nails to assert femininity and differentiate from girls. Commercially available henna dye has become increasingly popular in India, Europe, Canada, and the United States.

Regions in Pakistan, northern Libya, and northern India, with longstanding henna traditions, now develop innovative production methods, including glittering and gilding the dye. Historical changes in quality control, processing, and cultivation have improved the quality of dye available worldwide.

In Algeria, future mothers-in-law traditionally adorn brides with henna designs and jewelry. In India (among Hindu and Sikh communities), henna is central to wedding ceremonies, and it’s believed that the darker the bride's henna stain, the more she will be loved by her husband. Henna also features in many Hindu festivals. In Saudi Arabia, a female relative decorates the bride’s hand with henna for marital happiness. In Israel and the Middle East, henna parties—a ritual pre-wedding tradition—are held a week before the wedding. In Tunisia, henna wedding festivals can last up to seven days, with bride and groom both adorned.

Henna is hypoallergenic, strengthens and renews hair, and may help with dandruff issues. Folk tradition attributes antibacterial and antiseptic properties to henna, making it useful for fungal infections, eczema, and skin infections.

Only when processed into a paste do henna leaves leave traces on skin. For intricate designs, commercial henna powder is produced by drying, crushing, and sieving the leaves. The powder is mixed with water, tea, juice, or other liquids. To alter consistency, users may add sugar or molasses; essential oils further improve paste texture and application.

The paste rests for 1–48 hours before application. Timing is important for optimal results. To prevent the dye layer from drying out and flaking off prematurely, the paste is often sealed on the skin with lemon juice, or sugar is added to the mixture. Once dry, the paste is scraped off, leaving orange stains that darken to deep red over several days. The color lasts for several days before fading as the skin exfoliates.

The resulting shade depends on the original hair color, amount of dye, and ranges from light orange or yellowish through chestnut to burgundy red. To modify color, henna can be mixed with Cassia obovata for lighter/blonde hues or with indigo to achieve brown or black shades.

Cautions

Henna is known to be risky for patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency, more common in men, especially in the Middle East and North Africa. Some henna mixtures are hazardous due to added chemicals such as silver nitrate, pyrogallol, chromium, and other heavy metals, which can cause mild allergic reactions or significant inflammatory responses. The US FDA advises against applying adulterated mixtures directly to skin, and caution is also urged with “black henna” due to allergy risk.

Active Compounds

The most active compound in henna is lawsone (2-hydroxy-1,4-naphthoquinone), also called hennotannic or henna acid. This reddish-orange dye found in the leaves is used for body and hair art. Chemically related to juglone from walnut, lawsone combines with the skin’s protein, keratin, which activates it and allows it to absorb UV rays—useful in sun protection. Because of lawsone’s similarity to ninhydrin, used in forensics, it is being studied for possible future use in fingerprinting. Darker henna may include variable amounts of para-phenylenediamine.

Traditional Dosage

Dosage recommendations for henna are not specifically defined. Many recipes exist for color adjustment, application technique, and additives. Most agree on mixing henna with lemon juice or a mild acid (for longevity) or with herbs for fragrance or color modification.