Photo credit: Alexis Hennig, RHT
Thuja occidentalis / Thuja plicata (Cupressaceae): Eastern Arborvitae, Northern white cedar / Western red cedar
Author Chanchal Cabrera, RHT (BCHA).
Part used : young leaves and growing tips harvested in the spring
This is a large and stately conifer from the northeastern Americas, now naturalized into Europe and widely planted around the world as an ornamental. Although nomenclature was unreliable in the 1500s and other trees could be contenders, Thuja is believed to be the ‘tree of life’ that was given by the native Indigenous people to save the lives of the sailors of Jacques Cartier’s ill fated voyage in the winter of 1536, most of whom died of scurvy. The decocted boughs of thuja contain appreciable amounts of vitamin C as well as arginine, proline and other amino acids that act as synergists in connective tissue to reduce the symptoms of vitamin C deficiency.
Ancient peoples of the Mediterranean cultures burned the aromatic wood of local species of thuja (Thuja orientalis) along with sacrifices; indeed, “Thuja” comes from the Latin form of the Greek word thero (to sacrifice). Other species of thuja were used in Egypt for embalming the dead, evidence of the strong antimicrobial action of this plant.
This tree is not, in fact, a true Cedar but is a Cypress family It is an evergreen and reaches heights of 50 metres with buttresses at the base. Branches droop considerably then turn up at the ends. The leaves are scale-like and occur in pairs. They are an acid green at the tips in the spring, turning to a glossy dark green as they mature. In the species plicata the leaves are closely pressed to the stem and overlapped in a shingle arrangement. It has male and female parts separately on the same tree, pollen from the male parts being wind borne to the female cone in which the seeds develop. The bark on mature trees becomes a rich red brown and tends to peel off in shreds. The tree grows in moist to wet soils at relatively low elevations and forms dense forests with new trees growing off nurse logs and many forest floor plants in mature stands.
The medicinally active part is the leaf, preferably the leaf tips harvested in the early summer for maximum content of volatile oils. The volatile oil can be distilled out or the leaf tips can be soaked in alcohol or vegetable oil as a solvent. The leaf tips can also be boiled and the steam inhaled.
Astringent / cicatrant
Moth and insect repellant
Anti-neoplastic / antimitotic
The green spring tips have long been known for their antimicrobial action. They can be boiled up to make a tea for washing dirty wounds or for cleansing the sickroom, used as a gargle for throat infections and the steam inhaled for sinus and lung infections. The Eclectic herbalists of the 1800s made extensive use of this herb as a blood cleanser or depurative especially for old and festering sores and for benign skin growths. It was considered a stimulating expectorant and decongestant remedy, used to treat acute bronchitis and other respiratory infections, and a diuretic and astringent used to treat acute cystitis, bed-wetting in children and incontinence. It was also recommended in gynaecology for amenorrhea, leucorrhoea, endometrial overgrowth, ovarian cysts, polyps and uterine prolapse, and was used a douche for leucorrhoea, cervical dysplasia, yeast or bacterial overgrowth, herpes and genital warts. In men it was given by local injection for hydrocoele. Extracts were applied topically over stiff or painful joints or muscles as a counter-irritant, improving local blood supply warming the joint. It was also taken as a snuff or lavage for post nasal drip and for nasal polyps
Thuja also has a long and established history in homoeopathic medicine. In homeopathic medicine Thuja is a key remedy for skin and genito-urinary conditions with growths e.g. warts, skin tags, fibroids, uterine polyps, and especially as a depurative or blood cleanser where benign or malignant growths were considered to be a sign of blood dyscrasia. It is also recommended in homeopathy for people with low self-esteem and feelings of unattractiveness and worthlessness, for sharp left sided headaches in the temple or forehead and for a sensation of something is alive and moving in the abdomen, among other things.
Constituents and pharmacology
Oleo-resin up to 4%
monoterpene ketones: carvone , (-)thujone, isothujone, α and b thujone
monoterpene hydrocarbon: pinene
A bitter principle called pinipicrin
Coumarins (p-coumaric acid, umbelliferone)
Flavonoids (catechine, gallocatechine)
There is a wealth of research available today to validate the therapeutic claims of the past, and to explain the mechanisms of action of this herb. For the most part the traditional uses and the Eclectic medical recommendations are entirely supportable and still relevant today.
Volatile oils high in terpenes are directly antibacterial, antiviral and antifungal, tannins are astringent and cicatrizing, diterpenes and polysaccharides are immune-modulating and anti-inflammatory.
Actions and uses supported by research
Anti-inflammatory effects include downregulation of IL-6, TNF-α expression and COX-2
Antibacterial action is against both gram-negative/positive bacteria
Antifungal and Antiviral including Candida, HIV and herpes virus
Hepatoprotective, gastroprotective and anti-ulcerogenic (reduces gastric acid production, promotes regeneration of the gastric epithelium)
Improve lipid profile (increased HDL fraction) and anti-atherosclerotic
Redox regulating (radioprotective, anti-neoplastic)
Antifungal – the volatile oil may be applied undiluted to fungal skin infections such as athlete’s foot, tinea versicolor or ringworm. The tincture may be used internally to treat systemic Candida infections and also for Aspergillus and other fungal lung infections. It is also applied topically to warts.
Antibacterial – especially for upper respiratory tract infections. The volatile oil or the steam from boiling leaf tips may be inhaled in any congestive conditions of the upper respiratory tract especially where there is a lot of mucous being produced but little expectoration occurring. The Thuja will stimulate the muco-ciliary escalator, act directly against the pathogenic microbe and stimulate leucocytosis in the area.
Vulnerary – the alcoholic extract (tincture) was prized by the Eclectic physicians for treating chronic superficial injuries called by them fulminating ulcers or ulcerous epitheliomata. Today, while we no longer have to deal with such chronic conditions very often, we still find value in Thuja for treating diabetic or varicose ulcers and some of the more persistent tropical skin afflictions, bedsores and skin cancers.
Astringent – the tannic components contribute to an astringent and tightening action on the mucus membranes, particularly in the upper respiratory tract where there is a marked mucolytic effect. It has traditionally been used to treat hemoptysis and used to be valuable in the treatment of diphtheria and croup. Used in a sitz bath or in a cocoa butter suppository, it may also be useful to treat hemorrhoids or anal fissures. The Eclectics also used Thuja to treat strawberry naevi and port wine birth marks as well as in the form of a snuff or nose wash for nasal polyps and chronic sinusitis.
Female tonic – small doses of Thuja tincture act as a stimulating tonic to the female organs, being valuable as an emmenagogue for suppressed menstruation and as an anticatarrhal for any congestive conditions. It is especially indicated for a heavy, dull, aching sensations and for abnormal tissue growths such as fibroids, endometriosis and benign or malignant tumors. It may be used in the form of a douche to treat chronic leucorrhoea, vaginal Candida infections, or for vaginal polyps, cervical dysplasias or genital warts.
Male tonic – Thuja is frequently employed for congestive conditions of the prostate gland such as benign prostatic hypertrophy, as well as for mucous in the urine and for retention of urine. It may be applied topically to genital warts or for treatment of Candida infections. At the turn of the century Thuja tincture was employed as a treatment for hydrocoele. This was diluted in water and injected hypodermically into the tunica vaginalis of the testes and manually distributed into the whole scrotum. Considerable inflammation would occur but as it then resolved the varicocoele would usually resolve too.
Kidney / bladder tonic – Thuja is believed to give tone to the bladder walls and to reduce nocturnal enuresis and promote complete emptying of the bladder. Coupled with the pronounced immuno-stimulating, astringent and anti-catarrhal activity, this is a specific remedy for chronic urinary tract infections. Because of the irritating effect of the thujone, it is not recommended for those with acute renal infections.
Anti-cancer activity – Due in part to the diterpenes that mediate stress responses and inflammation, but also due to a synergy of constituents that cause antioxidant or redox regulating effects. In vitro studies show that α and β-thujone fractions kill cancer cells through inducing oxidative stress. Overall, the α and β-thujone fractions decrease the cell viability and exhibit a potent anti-proliferative, pro-apoptotic and anti-angiogenic effects. In vivo assays showed that α and β-thujone inhibit neoplasia and inhibit the angiogenesis (formation of new blood vessels in tumors)
Tincture 1 : 5 (40% EtOH) up to 3 mL three times daily
= 1.8 g equivalent dried herb daily
note that extraction with 35 – 40 % ethanol will remove the useful diterpenes and polysaccharides, but leave behind the thujone fractions and this will reduce toxicity.
The European Agency for the Evaluation of Medicinal Products (EMEA) gives the content of thujone in dried twigs as 7.6 mg /g, consisting of 85% α-thujone and 15% β-thujone. The maximum daily dose is suggested as 1.25 mg thujone/kg body weight, equivalent to 68 mg thujone / 55 kg person per day or 9 g per person per day of herb.
Tincture should be taken one month on, one month off.
Can be used topically as well, without limitation in unbroken skin, or alternating month doses in cases of open lesions.
The volatile oil may be purchased, taking care not to confuse it with essential oil of cedarwood which is quite different. This may be applied undiluted to warts or fungal infections or may be diluted for skin washing. It may also be employed in a vaporizer for inhalation.
Thujone is a constituent of commonly used herbs such as wormwood, yarrow, thuja and sage. This compound is somewhat neurotoxic and its presence in liqueurs such as absinthe may have contributed to widespread toxicity and abuse syndromes in the early 20th century, a contention that is currently being reassessed to take into consideration the amount of alcohol being consumed as well.
The first sign of toxicity from thujone is a headache. Thujone inhibits the gamma-aminobutyric acid A (GABA(A)) receptors of the brain, causing excitation and convulsions in a dose-dependent manner, and possibly inducing seizures. Care should be exercised when giving thujone-containing herbs in high doses to epileptics. These herbs include Thuja (Thuja occidentalis), sage (Salvia officinalis), tansy (Tanacetum vulgare), wormwood (Artemisia absinthium) and some types of yarrow (Achillea millefolium). High and prolonged doses of the above herbs are hence best avoided, unless they are low-thujone varieties.
Metabolism is mainly through CYP2A6 enzymes in the liver, followed by CYP3A4 and CYP2B6. This could be affected by drugs or other herbs that induce or inhibit them so care should be taken when prescribing Thuja for internal use that potential drug interactions have been considered.
Thuja should not be used for extended periods of time by those with kidney weakness and should be avoided in pregnancy where it may act as an abortifacient.
There is variation in the composition of essential oils of Thuja occidentalis L. from different trees and different locations, with one study suggesting ketone content varies from 58 to 77% of the essential oil. It is recommended to harvest from several trees in a location and from several locations to avoid a single tree or location that may be particularly high or low.
Thuja is the most widely used and versatile of all the trees indigenous to the Pacific North West. The wood is extremely rot resistant and was traditionally used to make the poles for longhouses, totem poles and dugout canoes. It was also used to make many tools and implements including fish spears, paddles and food drying racks. Certain tribes used hand hewn planks to make bentwood boxes, perfectly square and formed from a single plank bent and pinned. Mortuary boxes were always made from Thuja wood because the local traditions required that the body be preserved above ground in a raised box that was resistant to the elements. Before the arrival of the white man the natives made fabric for clothing from pounded sheets of Thuja bark and also used it to make beautiful baskets. It was considered by these people to be bad luck to fell a tree so they removed planks by driving antler wedges into the living tree along the grain to split off planks. When a whole tree was required to make a canoe or a longhouse pole, then either a naturally fallen tree was used or there would have to be offerings made to the Gods before a tree could be cut. The power of the Thuja was aid to be so strong that a person could receive spiritual healing by simply by standing with their back against a tree and one myth suggests that the Great Spirit created Thuja in honor of a man who was always helping others: “When he dies and where he is buried, a cedar tree shall grow and be useful to the people – for baskets, for clothing and for shelter”.The inner cambium layer of the bark was even eaten in times of famine as a survival food.
In the Pacific Northwest the indigenous peoples of the region called this tree the grandmother of the forest as it was often the oldest and the largest tree in the forest and it provided for so many of their needs. This idea of the generous and benevolent grandmother, helping the people who love her, is borne out today in a more literal way by research at the University of British Columbia. Here Dr. Suzanne Simard has established that these venerable old trees, with a huge photosynthetic capacity, are making a lot more sugars than required for their own energy needs, and are in fact ‘feeding’ sugars via mushroom mycelia into the root systems of nearby seedlings that are still struggling to grow up above the competition on the forest floor.
The Thuja was used for many medicinal purposes as well. The green immature cones were chewed and the juice swallowed as a contraceptive for women to prevent implantation of the egg. The smoke of the smouldering branches was used as a traditional ‘smudge’ to ward off evil spirits and to cleanse sick rooms. Similarly, the green branches were used to splash water on the stones during the traditional ‘sweat lodge’ ceremony. The branches were also used in the form of a strong tea to wash rheumatic limbs.