Is Osha Root Antiviral? What the Lab Research on Osha Has Found

In 2008, a researcher at the University of Texas at El Paso mixed an ethanol extract of osha root into cultures of Mycobacterium tuberculosis, the TB bacterium. At 5 µg/ml, the lowest concentration he tested, the extract stopped more than half of the growth. People who ask whether osha root is antiviral have usually heard it from Diné, Zuni or Rarámuri tradition. The lab work that followed has tested the root against TB, staph and E. coli, and the clearest antiviral result belongs to Z-ligustilide, a compound osha root carries in quantity.

Is osha root antiviral in lab tests?

The antiviral data centre on Z-ligustilide. In a US patent granted in May 2024, scientists Lijun Song and Wenchang Zhao of Guangdong Medical University reported that Z-ligustilide at 80 µM cut rotavirus replication in cell culture by 64.21%. Their positive control was ribavirin, a prescription antiviral, and they found no statistical difference between the two. At 65 to 90 µM, more than 95% of the cells stayed alive. The compound worked on the virus copying itself inside the cells, and the team measured a significant drop in the virus's VP6 gene at 75 to 85 µM.

Osha root is one of the richest natural sources of this compound. Published analyses put Z-ligustilide at 0.15 to 2.5% of the dried root, and a 2005 analysis (below) found it made up 39.1% of a solvent extract of the root's oil.

The 2008 TB study at UTEP

Oscar Beltran's master's thesis at the University of Texas at El Paso tested three plants that the Tarahumara (Rarámuri) and other groups in Northern Mexico and the Southwest use against TB. One was Ligusticum porteri, called chuchupaste in the study. He grew the H37Rv strain of the bacterium for four to six weeks with each extract, alongside the standard TB drugs isoniazid, rifampin and ethambutol as comparisons.

Osha stopped more than half of the bacterium's growth at 5 µg/ml. Human immune cells (the U-937 line) showed no harm from it until 50 to 100 µg/ml, a wider margin than either of the other two plants. Presenting the work with M. M. Weigel and Rodrigo Xavier Armijos at the World Congress on Public Health in Istanbul in 2009, the team reported that osha's MIC50 was about half that of the other plants and its therapeutic index was greater than 10. They named osha the plant with therapeutic potential.

Is osha root antibacterial?

Researchers at the Universidad Autónoma de Chihuahua (S. Andrade-Ochoa, K. G. Chávez Villarreal, B. E. Rivera-Chavira and G. V. Nevárez-Moorillón) tested the essential oil of Ligusticum porteri, which they describe as endemic to Chihuahua and Sonora, against 12 bacteria. Their abstract, shared through the Mexican Society of Biotechnology and Bioengineering in 2013, gives these minimum inhibitory concentrations:

• E. coli, Staphylococcus aureus, Enterococcus faecalis and Staphylococcus epidermidis: 100 µg/ml
• Salmonella typhi and Shigella flexneri: 250 µg/ml
• Listeria monocytogenes: 500 µg/ml
• Bacillus cereus, Klebsiella pneumoniae and Klebsiella oxytoca: 750 µg/ml

They traced the activity to the root's monoterpenes and phthalides (p-cymene, limonene, alpha- and beta-phellandrene, alpha-pinene, diligustilide and riligustilide) and called the oil's components worth studying as drug candidates.

A 2005 paper in the Flavour and Fragrance Journal, led by Pascale Cégiéla-Carlioz with Simon Gibbons and Marie-Geneviève Dijoux-Franca, looked at drug-resistant staph. They gave a norfloxacin-resistant strain of S. aureus the antibiotic plus osha oil at 100 µg/ml. The oil made norfloxacin two times stronger when steam-distilled and four times stronger when solvent-extracted. The strain resists by pumping the drug out through NorA, which the authors call the major drug pump in this bacterium.

What's in the root

That same 2005 team identified 42 compounds in osha root oil. The water-distilled oil was 56.6% sabinyl acetate and 12.9% Z-ligustilide. The dichloromethane extract flipped the balance: 39.1% Z-ligustilide and 34.6% sabinyl acetate. Z-ligustilide belongs to the phthalides, the compounds that give celery and lovage their smell. Osha sits in the same family (Apiaceae), which is why the root has that sharp, celery-like bite.

For a full profile of the plant, from its 1,500 to 3,500 m habitat to how it's harvested, see our complete guide to osha root.

Osha root research started with what people already used

The UTEP thesis exists because Rarámuri healers already used the root against TB. The scientists followed the tradition, and it runs deep across the region.

The Diné used osha for a hoarse voice and credit the medicine to the bear. Zuni healers used it for sore throats and body aches. Rarámuri families in Northern Mexico brewed it as a tea for stomach pain and fever. In New Mexico, chuchupate tea is a household remedy for sore throats, and the Comanche used the root for pneumonia (more on that history in osha root and the lungs). The Lakota name, mato tapejuta, means bear medicine. A piece of the root turned up in a Utah medicine bundle dated 200 to 600 years old. And the observer Shawn Sigstedt watched Kodiak bears chew the root and rub it into their fur.

Taking osha as Bear Root

Every lab result above came from an extract: an ethanol extract at UTEP, the root's oil in Chihuahua and France. Bear Root is that form. It is an osha root tincture (an alcohol extract) of Ligusticum porteri, a mountain plant of Northern Mexico, the same region where the Rarámuri use it and where the Chihuahua team describes the plant as native.

Most people take 1 to 2 droppers a day. Hold it under the tongue for 20 to 30 seconds and swallow, or stir it into water, tea, juice or a smoothie. The taste is earthy and warming, with the sharp celery-like bite of the root. It fits a morning tea, a water bottle after a hike or run, or an evening cup, any time of year. A 50 ml bottle lasts 30 to 50 days.

The tincture sits in dark Miron glass. Amber glass is a step in the right direction; Miron is the gold standard, and it keeps light off the extract so each dropper tastes the same at day 40 as on day one. There's no root to chop and no powder going stale in a jar. Simple ingredients: premium quality extract.

Bear Root – Osha Root Tincture

50 ml dropper bottle. Ligusticum porteri from the mountains of Northern Mexico.

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Bear Root considerations

The product page recommendation: "Contains alcohol. Not recommended during pregnancy. If you're nursing or taking medication, ask your doctor before using it."

Questions people ask about osha research

What compound in osha root has been tested against viruses?

Z-ligustilide. Guangdong Medical University scientists reported in a 2024 US patent that it cut rotavirus replication in cell culture by 64.21% at 80 µM, level with the antiviral ribavirin.

Which bacteria has osha root been tested on?

The TB bacterium (University of Texas at El Paso, 2008), drug-resistant Staphylococcus aureus (Cégiéla-Carlioz and colleagues, 2005), and 12 bacteria including E. coli and Enterococcus faecalis at the Universidad Autónoma de Chihuahua.

Is chuchupate the same as osha?

Yes. Chuchupate (also spelled chuchupaste) is the Northern Mexico and New Mexico name for Ligusticum porteri, the plant in Bear Root.

How do you take an osha root tincture?

Take 1 to 2 droppers a day, held under the tongue for 20 to 30 seconds or stirred into water or tea.