Manjistha (Indian Madder) in Soap: Colour, Tradition and Evidence

Manjistha is the Ayurvedic name for Rubia cordifolia, known in English as Indian madder, and in soap it works mainly as a natural red colourant. Its colour comes from anthraquinone dyes, and the shade shifts with pH. Claims that it treats skin conditions rest on tradition and laboratory work, not on proven human results.

What is manjistha?

Manjistha is Rubia cordifolia, a climbing plant in the coffee family, Rubiaceae, cultivated for a red pigment. In English it is Indian madder. The Ayurvedic Pharmacopoeia of India lists the names Yojnavalli, Vastrarajini and Rakta in Sanskrit, Manjitha or Manjit in Hindi, and Manjishtha in Telugu.

A related madder, Rubia tinctorum, is a separate species. That difference matters for safety, which is covered further down. For the chemistry of the soap itself, see what saponification is.

Is manjistha a root or a stem?

Both descriptions exist. The Ayurvedic Pharmacopoeia of India defines manjistha as the dried stem of Rubia cordifolia, while botanical and dye references describe the root as the source of the red pigment. The part used depends on the source, so a label that says only manjistha does not tell you which.

The pharmacopoeia describes the powder as pink. Colour in soap depends on more than the plant part, as the next sections explain.

What colour does manjistha give a soap?

Manjistha gives soap a colour in the red to brown range, with the exact shade depending on the amount, the preparation and the soap itself. Its colour components are mainly anthraquinones, and dyes from the plant fall in the yellow-red part of the colour space in dye studies.

Makers add the plant as a powder or as an infused oil. In cold process soap it meets an alkaline batter, and the amount and the soap base also change the result, so two makers rarely get the same shade. Plant colours can also change over time, so it is sensible to store bars away from strong light.

Why does the colour of manjistha soap shift?

The colour shifts because anthraquinone dyes change colour with pH. Alizarin, a madder dye, runs from yellow to purple across pH 2 to 12 in laboratory films. Bar soap is alkaline, with bars measuring pH 8.01 to 11.01 in one survey, so manjistha can look different from the pour to the cured bar.

Why soap is alkaline is explained in why real soap is alkaline. Because the dye is pH-sensitive, a shade that differs between a fresh bar and a later one is expected, and is not a defect.

Which compounds in madder matter for colour and safety?

Madder roots contain several anthraquinone compounds, and they differ in what is known about them. The table names five and says where each stands. The evidence on skin is laboratory and animal work, and the safety signals come from the related European madder, so read the last column with care.

What are the traditional uses of manjistha in Ayurveda?

In Ayurveda, manjistha is a drug with a long list of uses. The pharmacopoeia monograph lists complexion-supporting (varnya) and skin-disease (kusthaghna) actions, with uses that include kustha (skin diseases) and vyanga (a facial pigmentation condition). The listed oral dose is 2 to 4 g of the drug.

That history is genuine, and it explains why manjistha appears in Indian skincare. Tradition records what practitioners have long used the plant for. It does not show that a rinse-off soap does the same.

What does the evidence say about manjistha for skin?

The evidence for skin is preclinical, meaning cells and animals. A 2003 laboratory study found that Rubia cordifolia suppressed inflammatory mediators triggered by acne bacteria in cells. A root fraction slowed keratinocyte growth and thickened mouse skin in a psoriasis model. A 2025 study found that alizarin from the plant eased psoriasis-like lesions in mice.

The one human trial we found tested an oral supplement for four weeks in 31 healthy adults and looked at gut bacteria, not skin. We found no human trial of manjistha in a soap. A bar is on the skin only briefly, so results from concentrated extracts in cells or from mouse skin should not be read as results for a bar.

Is manjistha safe?

Manjistha has a long traditional record, but safety data are thin and the closest warnings concern the related European madder. A 2026 review reports that chronic use of Rubia tinctorum induced liver and kidney tumours in mice, with lucidin, rubiadin and alizarin among the carcinogens it names, and that the Rubia species share only a limited set of constituents.

Those findings concern Rubia tinctorum eaten or fed to rodents, not Rubia cordifolia in a rinse-off bar. They are a reason to avoid taking madder by mouth without medical advice. We found no study that shows harm from washing with manjistha soap, and none that shows it is risk-free.

How do you spot manjistha on a soap label?

Look for the plant named by its botanical or common name. The label may say Rubia cordifolia, Indian madder or manjistha. Check also that the ingredient list does not rely on a synthetic colourant, which would appear as a CI number. The label guide explains how to read the full list and tell cold process soap from a coloured base.

Slight variation between bars in one batch is normal for a plant colour. A maker who explains the part used and the amount is giving you better information than one who only says natural. For another Indian botanical with a similar tradition-versus-evidence story, see tangedu.

The short version

Manjistha is Indian madder, an Ayurvedic ingredient and a source of anthraquinone dyes. In soap it is first a colourant, and its shade depends on pH. Evidence for skin benefits comes from cells and animals, and the safety warnings come from a related species. A good manjistha bar is worth buying for its colour and its craft.