Creosote bush (Larrea tridentata) is one tough plant. Able to thrive beneath the unrelenting sun of the Chihuahuan, Mojave, and Sonoran deserts, it flourishes where other arid land plants retreat. An evergreen shrub, its small, waxy leaves are browsed by deer and rabbits only as a last resort during lean times. Its delicate yellow blossoms lead to pea-sized, fuzzy gray fruits that are eaten by kangaroo rats, birds and ants. It commands acres of the harshest land in the United States and Mexico, growing in uniformly-spaced stands on desert flats and altering its growth habit to compete with shifting sand dunes. Its mastery of the landscape earned it the name La Gobernadora, the governess, from Spanish settlers, and the name Shegoi, “mother of all plants”, from the Tohono O’odham tribe.
Daniel Moerman’s encyclopedic tome, Native American Ethnobotany (Timber Press 1998), lists the historic uses of Larrea tridentata by 13 tribes of the desert southwest. Aside from its medicinal use, the book lists other uses of Creosote: building material, fiber, tools and weapons, musical instruments, and decoration – its charcoal produces a greenish blue color in tattoos.
When used as a remedy, the methods of extraction and application of the plant material varied amongst the different tribes. For example when used as an anti-rheumatic (a remedy that provides relief from any painful or immobilizing disorder of the musculoskeletal system) some tribes boiled the plant in water (a decoction) while others allowed the plant to steep in hot or cold water (an infusion) . Depending on the tribe, these water extractions were then employed as a tea, a wash, or a bath. Heating or burning the branches was another extraction method. The warm branches were used as a poultice or the aching body part was held over smoldering branches.
Review the list of uses for Creosote in Moerman’s book and a consensus is revealed about the body systems, or tropisms, for which the Indigenous people used this herb. It has an affinity for the skin, the lungs, the intestines and the urogenital organs. And, not surprisingly, modern scientific research continues to confirm these affinities. Journal articles published within the past year have focused on the herb’s assumed active ingredient, nordihydroguaiaretic acid (NDGA), and its use against MRSA (methicillin-resistant Staphylococcus aureus); against a hard-to-treat form of lower respiratory tract infection; to prevent ischemia during re-perfusion of kidneys (reintroduction of blood during surgery); and for potential use against cancers of the breast, colon, and skin.
Creosote has a number of qualities that make it attractive to mine for potential pharmaceuticals. It is antiviral, antifungal, and antibiotic. It is analgesic and antitumorigenic. It inhibits inflammatory pathways and acts as an immunosuppressive. More than one abstract describes it as having “super antioxidant properties”. When NDGA was discovered in 1945, it was immediately adopted as a food and pharmaceutical preservative. Industry used it to preserve lard, oil, candies, baking mixes, frozen foods, vitamins and drugs. That use ended in 1967 when a rat study showed the compound to be toxic to the liver and kidneys and the Food and Drug Administration removed it from its GRAS list (Generally Regarded As Safe).
Over the years similar studies have alternately agreed and disagreed with the original results: some findings affirm hepato- and nephro-toxicity, others disprove it. This controversy carries over into the herbal world where some herbalists encourage the internal use of L. tridentata while others recommend only external use. A possible explanation for this contradiction in the threat for toxicity may lie in the mechanism by which the body metabolizes NDGA via glucoronidation (a pathway that the body uses to rid itself of some compounds including drugs, pollutants, estrogens and stress hormones). The efficiency of this pathway is not the same for everyone, it varies among individuals. The level of efficiency can be influenced by diet, stress, and other environmental and genetic factors. According to this theory, the potential toxicity of L.tridentata for a particular individual could be determined by the status of that individual’s detoxification pathway. Based on this individuality, we can further theorize that a woman, for example, given Creosote capsules to address fibroids, could have a glucoronidation pathway already overwhelmed with estrogens or stress hormones. That overwhelmed detoxification pathway could increase the likelihood that the herb is toxic for that individual. It’s just a theory, but worth considering.
Consider too that even with external use, Creosote still find its way into the bloodstream. It’s a good thing that just a bit of the salve goes a long way. Around my house, we smudge it on insect bites to stop itching and calm redness. A blob on an adhesive bandage works better (in my opinion) than a commercial triple antibiotic ointment for preventing infection and encouraging skin repair. For fungal infections, Creosote shines! It takes longer to show results on a slow-growing, funky toenail, but it makes short work of athlete’s foot. For sun-damaged skin, I feel like something of Creosote’s punishing habitat is channeled into the remedy, as if it says, “Sun-damaged skin? Oh honey, I know how to handle that!”
Moerman, D.E. (1998) Native American Ethnobotany. Portland, Oregon: Timber Press, Inc.