Question 1

How does Lawsonia inermis work as a dye and medicinal agent?

Accepted Answer

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.

Question 2

Is Lawsonia inermis safe to use during pregnancy?

Accepted Answer

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.

Question 3

What is the recommended dosage for Lawsonia inermis?

Accepted Answer

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.

Question 4

Does Lawsonia inermis interact with medications?

Accepted Answer

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.

Question 5

Who should avoid using Lawsonia inermis?

Accepted Answer

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.

Lawsonia inermis

Sources & Citations

Summary

Background

Traditional uses

Active compounds

Mechanism of action

Clinical evidence

Safety & adverse effects

Evidence summary

PubMed sources

Government sources