The Safety of Low-Dose Larrea tridentata
(DC) Coville (Creosote Bush or Chaparral):
A Retrospective Clinical Study
SILENA HERON, N.D., and ERIC YARNELL, N.D

THE JOURNAL OF ALTERNATIVE AND COMPLEMENTARY MEDICINE
Volume 7, Number 2, 2001, pp. 175–185
Mary Ann Liebert, Inc.

ABSTRACT
Objective: To determine whether internal use of low doses of Larrea tridentata tincture or topical
applications of this traditional herbal medicine are safe.
Design: Retrospective review of all people prescribed Larrea for internal or for topical use over
a 22-month period.
Setting/Location: A general naturopathic practice in Sedona, Arizona.
Subjects: Thirteen patients were identified for whom Larrea tincture for internal use was prescribed.
An additional 20 female and 3 male patients were identified for whom an extract of Larrea
in Ricinus communis (castor) oil for topical use was prescribed. No patient had any history of
liver disease.
Interventions: Larrea was prescribed as part of the usual care of each patient. In all cases it
was given as either part of a complex herbal formula individualized for each patient containing
less than 10% Larrea tincture or as an extract in Ricinus oil for topical use.
Outcome Measures: Serum liver enzyme levels as well as blood urea nitrogen and creatinine
levels, glucose levels, electrolytes, bilirubin levels, iron levels, ferritin levels, lipid levels, and
complete blood count (CBC) were available for analysis in four patients; general clinical history
and physical examination findings were relied on in all other cases.
Results: The four patients with complete before and after blood chemistry panels and CBC
had no indication of liver damage from use of Larrea. This included one patient who was taking
medications with significant potential for hepatotoxicity. No patient in the study, whether
using Larrea for short term or long, internally or externally, showed any sign of organ damage
during the period of follow-up.
Conclusions: Relatively small intakes of Larrea tincture, or topical application of extracts in
Ricinus oil, are safe when prescribed by a clinically trained botanical prescriber. Larrea should
be used with caution in persons with a history of previous, or current, liver disease. It may be
preferable to avoid the use of Larrea capsules because they have been associated with potentially
dangerous overdosing.
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