MS-N148 · Cancer control · Negative historical evidence · Liver safety · Human evidence · Appraised 26 October 2026

Does chaparral (Larrea tridentata, creosote bush) or its lignan NDGA control advanced cancer?

Evidence at a glance

• Evidence label: Historical uncontrolled study did not establish meaningful benefit; serious liver injury is documented
• Benefit: A 1970 uncontrolled study reported a few short or liberally defined regressions, not durable evidence of efficacy.
• Certainty: Low for efficacy because the study was uncontrolled and poorly reported; moderate for the liver-injury signal from case series and rechallenge evidence.
• Risk: Clinically apparent hepatitis, cirrhosis, acute liver failure, transplantation and death have been reported.

What was studied

Traditional context: Chaparral has documented use among Indigenous peoples of the Southwestern United States and northern Mexico, often as water-based preparations for a range of conditions. That cultural history should be described respectfully and separately from modern claims that capsules or extracts cure cancer.

Historical cancer study: A 1970 report enrolled 59 people with advanced incurable malignancy to chaparral tea or nordihydroguaiaretic acid (NDGA); outcomes for 45 treated at least 4 weeks were analyzed. There was no randomized comparator, and response criteria were far less rigorous than current standards.

What the evidence found

Excluding the melanoma case that prompted the study, three of 44 evaluated patients were described as having tumor regression, using a liberal threshold of 25% shrinkage; one reported response lasted only 10 days. This pattern did not establish a clinically meaningful anticancer effect.

Absence of liver injury in that small, short trial does not establish safety. Later reports linked chaparral products to hepatocellular injury, cirrhosis and acute liver failure; a U.S. case series summarized 13 reports, including two liver transplants and four cases progressing to cirrhosis.

How to interpret it

Preparation matters—tea, capsule and isolated NDGA are chemically different—but there is no preparation with reliable evidence of cancer control. Traditional use cannot be generalized to concentrated commercial products or oncology dosing.

A few regressions in an uncontrolled study are vulnerable to measurement error, spontaneous fluctuation, prior therapy and selective reporting.

Practical safety context

Avoid internal chaparral use during cancer treatment, especially with liver disease, alcohol-related injury or hepatotoxic medicines. Stop and seek prompt assessment for jaundice, dark urine, pale stool, severe itching, right-upper-abdominal pain, persistent nausea or unusual fatigue. Liver injury can be severe and unpredictable.

Questions for the care team

• What exact plant species, plant part and preparation is being proposed?
• Is the claimed response based on modern imaging criteria and a controlled comparison?
• Which current treatments or conditions already place the liver at risk?

Funding and conflicts

Funding and conflict declarations were not available in the 1970 abstract and historical report. Later safety assessments synthesize case reports and cannot estimate incidence, but rechallenge and severe outcomes support a real causal risk.

Sources

• 1970 advanced-cancer study (PMID 5480535)
• Chaparral-associated hepatotoxicity case series (PMID 9129552)
• NIH LiverTox: Chaparral
• National Academies chaparral safety monograph
• Review of commonly used herbal medicines in Mexico

Last literature search: 26 October 2026. Record appraisal: 26 October 2026. This page is educational and does not replace individualized medical advice. Laboratory effects, biomarkers, symptom changes or an uncontrolled response must not be interpreted as proof of tumor control, delayed recurrence or longer survival.