Nilavembu

Nilavembu is Andrographis paniculata, the fiercely bitter green that Tamil households know as a decoction in fever season and that Hindi trade calls kalmegh. Recent epidemics attached disease slogans to it that the evidence does not carry.

Botanical name

Andrographis paniculata (Burm.f.) Nees

Family

Acanthaceae

Tamil

Nilavembu

Hindi

Kalmegh

Sanskrit

Kālmegha

Parts used

Whole herb, Leaves

Habit

Erect bitter annual of tropical Asia

Last updated

2026-10-30

How to recognise Nilavembu

The accepted name is Andrographis paniculata (Burm.f.) Nees, family Acanthaceae. Burman published it as Justicia paniculata; Nees placed it in Andrographis in 1832. The stem is square and winged; leaves are lance-shaped and hairless; flowers are small and pale with darker marks, in spreading panicles; the fruit is a thin capsule that pops.

The taste is the household test: persistently, almost aggressively bitter. That is why English called it creat or king of bitters. Bitterness is not a proof of purity in a factory juice.

Tamil nilavembu and Hindi kalmegh are the usual names when the seller means this species. Other bitter Andrographis and Justicia plants exist. A dried powder cannot be identified by colour.

It grows as an annual in plains and low hills of south India and Sri Lanka and is cultivated elsewhere. A roadside patch in Tamil Nadu after the rains is a common picture.

During dengue and COVID years, nilavembu kudineer was sold as if it were a public-health product. A traditional decoction and a licensed medicine are not the same thing.

Traditional use of Nilavembu

Siddha

Nilavembu appears in Siddha decoctions used in seasonal fevers. Those recipes belong to trained practice and to a humoral system. Repeating them as a treatment for a named virus would be both dishonest and unlawful.

Siddha naming and household decoction practice

Ayurveda

Kālmegha is a bitter herb in Ayurvedic lists. Traditional use includes liver and fever categories in that system, not ICD diagnoses.

Ayurvedic materia medica headings

Modern notes on Nilavembu

Andrographolide chemistry is well described. That does not turn a boiled handful of stems into a standardised extract, and it does not show an effect on infection or cancer.

Reviews of trials for colds exist and are cautious.

IUCN and trade notes treat the plant as common and heavily collected. The risk in India is over-harvest of wild patches and wild claims, not a missing Latin name.

Factory juices sold in fever season are a different object from a handful of stems boiled at home. Strength, plant part and what else went in the vat are usually unstated.

Nilavembu safety

The decoction is very bitter and can bother the stomach. Concentrated extracts are stronger.

People who are pregnant, trying to conceive, or on many medicines should not start Andrographis from a poster at a tea shop.

Nilavembu is not a proven treatment for dengue, influenza or any other named disease.

Ecology and sourcing

Cultivation is straightforward in a sunny bed. Wild collection of whole plants for seasonal panics is how a common herb becomes locally scarce.

Related plants

Also in Acanthaceae

Questions about Nilavembu

What is the botanical name of nilavembu?

Andrographis paniculata (Burm.f.) Nees, family Acanthaceae.

Is kalmegh the same plant?

Kalmegh is the common Hindi trade name for the same species.

Sources

• Andrographis paniculata (Burm.f.) Nees — Plants of the World Online, Kew (accessed 2026)

Educational page about a plant. It is not medical advice, not a diagnosis, and not an offer to sell. Traditional use is historical. If you need care, ask a licensed clinician. Questions: hello@meevamed.com.