Botanical Name: Thymus vulgaris, Lamiaceae

Common names: Thyme, Common Thyme, Garden Thyme

Plant description: Thyme is a small, shrub 10-30 cm in height, with numerous brittle branches and a woody fibrous root.  The stem is square Leaves are opposite, quite small and numerous, ovate-lanceolate, margins entire. Flowers very small, carried in leafy and terminal whorls, bluish to purple in colour.  The entire plant is highly aromatic.

Habitat, ecology and distribution: The Wild Thyme (T. serpyllum) is said to be native to southern Europe and northern Africa, preferring dry habits and light soils.  Grieve reports that the richer the soil the less aromatic the plant (1971, 809).  Common or Garden Thyme is thought to be a cultivated species of Wild Thyme.

Part used: Aerial parts.

History: The genus name Thymus is of Greek origin, thought either to be derived from a word that means 'to fumigate,' or from the word thumus, meaning courage.  Thyme is mentioned in Virgil's Georgics and by Pliny as a fumigating agent (Grieve 1971, 809). In the Capitularies of Charlemange, a text that lists the various ordinances of the emperor's rule, it is said that Thyme should be grown in abundant volumes in monastery gardens and made available to the general populace because of its health-giving properties (Weiss 1988, 208).  In medieval Europe Thyme was considered to be an emblem of bravery and courage, and it was the custom for ladies to embroider a bee hovering over a sprig of Thyme on the scarves they presented to their knights (Grieve 1971, 809).  Grieve mentions that Thyme is a favorite of honey bees, and is the source of the nectar that bees use to make the famous Hymettus honey near Athens, Greece (1971, 809).  Thyme is also commonly used as a flavoring agent in cheese and liqueurs, and is an important culinary herb in French cuisine.

Constituents: The key constituent in Thyme is the essential oil, which comprises upwards of 1-2.5% of the plant, including the monterpenes thymol (30-70%), carvacrol (70%) and thymol methyl ester (1.5-2.5%), as well as p-cymene, linalool, alpha-terpineol and thujan-4-alcohol.  Other important constituents include flavonoids, including methylated flavones, phenolic glycosides and aliphatic alcohols, as well as biphenyl compounds, phenolic acids such as rosmaric acid, resins and tannins (Mills and Bone 2000, 564; Newall et al 1996, 256).

Medical Research: There have been a few clinical trials with Thyme and thymol.  In one double-blind placebo-controlled trial of 60 patients with productive cough the effectiveness of a Thyme syrup or bromohexine was compared, the results indicating that Thyme syrup is just as effective as the drug to improve symptoms.  Two cases of vulval lichen sclerosis were successfully treated with the topical application of a cream containing Thyme extract (Mills and Bone 2000, 566).  In the treatment of Kaposi's sarcoma a daily dose of 1-4 g of thymol, dosed in two cycles of 64 and 169 days, was found to be successful.  In one of case of dermatomyosis and another of progressive scleroderma, the administration of thymol was shown to resolve the progression of the disease (Mills and Bone 2000, 566).  The following is an overview of the experimental data on Thyme:
•Antispasmodic: Concentrated Thyme extracts have demonstrated an antispasmodic in vitro, enhancing the relaxation effect of bradykinin.  The essential oil of Thyme, the purified flavonoids and concentrated extracts of the crude herb have been shown to inhibit tracheal smooth muscle cell contraction, phasic contractions in ileal muscle, and the contraction of the vas deferens, in vivo.  The antispasmodic activity appears to be greatest on tracheal muscle, perhaps by inhibiting calcium ion flux (Mills and Bone 2000, 564).
•Antimicrobial: Concentrated extracts of Thyme, as well as the essential oil and its purified components the monoterpenes thymol and carvacrol, have all demonstrated antimicrobial properties in vivo against gram negative and gram negative bacteria, including pathogenic oral bacteria Porphyromonas gingivalis, Selenomonas artemidis and Streptococcus sobrinus, as well as other bacteria including Salmonella typhimurium, Sarcina and Staphylococcus spp.  Both aqueous and ethanolic extracts of Thymus were found to significantly inhibit Helicobacter pylori (Mills and Bone 2000, 564-65).
•Fungicidal: Thymol and carvacrol, as well as the essential oil of Thyme, have been shown to exhibit an in vitro antimicrobial property against several species of fungi, including Cryptococcus neoformans, Aspergillus spp., Rhizoctonia solani, Pythium ultimum, Fusarium solani and Colletotrichium lindemuthianum (Mills and Bone 2000, 565)
•Antioxidant: Thymol has been shown to cause a dose dependent inhibition of endothelial cell mediated oxidation of low density lipoproteins, and both thymol and carvacrol have demonstrated the ability to inhibit peroxidation of phospholipids and an ability to scavange peroxyl radicals, in vitro.  Rosmarinic acid has demonstrated an ability to inhibit lipid peroxidation, decrease the production of the super oxide radical, and inhibit the oxidative effects of polymorphonuclear leukocytes, in vitro.  The biphenyl compound 3,4,3',4'-tetrahydroxy-5,5'-diisopropyl-2,2'-dimethyl-biphenyl, as well as the flavonoid eriodictyol, were found to inhibit super oxide anion production and lipid peroxidation, the biphenyl compound in particular protecting red blood cells against oxidative hemolysis (Mills and Bone 2000, 565).
•Antimutagenic: The flavonoid luteolin isolated from Thyme was found to possess antimutagenic properties against dietary carcinogens derived from cooking.   In another study a Thyme extract demonstrated antimutagenic activities, modulating the effects of DNA repair in Escherichia coli by stimulating error-free repair (rather than a suppression of error-prone repair) (Mills and Bone 2000, 565).
•Antiinflammatory: Rosmarinic acid has been shown to demonstrate an ability to inhibit the activation of complement protein C3, preventing immunohemolysis of erythrocytes in vitro. The oral administration of rosmarinic acid has also demonstrated passive cutaneous anaphylaxis in rats at doses of 1-100 mg/kg.  Thymol has been shown to inhibit neutrophil chemotaxis, and Thyme oil has been shown to inhibit prostagladin synthesis, in vitro (Mills and Bone 2000, 565).

Toxicity: Mills and Bone report that the LD50 of the essential oil is 2.84 g/kg in rats (route administered not given), and that oral doses of 0.5-3 g/kg of a concentrated Thyme extract decreased locomotor activity and slightly slowed the rate of respiration in mice (2000, 566).  Newall et al report an oral LD50 for Thyme oil in rats as 4.7 g/kg.  Thyme oil is considered a dermal and mucus membrane irritant and should not be taken internally or applied to skin.  Toxic symptoms for thymol include nausea, vomiting, gastralgia, headache, dizziness, convulsions, coma, and cardiac and respiratory arrest.  Hyperemia and inflammation have been noted in topical and bath preparations that use the essential oil (Newall et al 1996, 256).  The crude herb is generally recognized as safe, used as a medicine, food and condiment.

Herbal action: antispasmodic, carminative, expectorant, antiseptic, antimicrobial, antioxidant, emmenagogue, rubifacient

Indications: dyspepsia, gastritis, asthma, bronchitis, pertussis, laryngitis, tonsillitis, dysmenorrhea; topically for fungal and bacterial infections, gingivitis

Contraindications and cautions: None found.

Medicinal uses: Grieve states that an infusion of Thyme can arrest gastric fermentation and is useful in gastrointestinal spasm and colic (Grieve 1971, 811). According to Felter and Lloyd, the cold infusion is useful in dyspepsia, with weakness and irritability of the stomach, "…and as a stimulating tonic in convalescence from exhausting diseases" (1893).    As a diaphoretic, the hot infusion can assist in promoting perspiration at the commencement of a cold or fever (Grieve 1971, 811), and is useful in dysmenorrhea, flatulence, colic, and headache (Felter and Lloyd 1893).  According to Culpepper, Thyme is "…a noble strengthener of the lungs, as notable a one as grows, nor is there a better remedy growing for hooping cough. It purgeth the body of phlegm and is an excellent remedy for shortness of breath. It is so harmless you need not fear the use of it. An ointment made of it takes away hot swellings and warts, helps the sciatica and dullness of sight and takes away any pains and hardness of the spleen: it is excellent for those that are troubled with the gout and the herb taken anyway inwardly is of great comfort to the stomach."  Gerard adds that it will "…cure sciatica and pains in the head," also indicated in leprosy and the epilepsy. Weiss states that the oil when taken internally is eliminated by the alveoli of the lungs, exhibiting an antimicrobial as well as spasmolytic activity on bronchial spasm (1988, 208).  To this extent Thyme is sometimes referred to as 'tracheal relaxant,' used in convulsive coughing from infectious or allergic causes.  Thyme is especially indicated in whooping cough, or pertussis, and represents a viable alternative to the pertussis vaccine. For sore throat, tonsillitis and laryngitis, the diluted tincture or strong infusion is a useful remedy.  For gingivitis a dilute tincture of Thyme can be used as a mouthwash. Felter and Lloyd state that the "…oil is valuable as a local application to neuralgic and rheumatic pains" (1893), but should not be applied to the skin without a carrier.  Mills and Bone suggest that Thyme may be helpful as an antioxidant and hypolipidemic agent, useful in cardiovascular disease, and as an adjunct in the treatment of gastric ulcer (2000, 563).

Pharmacy and dosage:
•Fresh Plant Tincture: fresh herb, 1:2, 95% alcohol, 20-40 gtt, 1-5 mL
•Dry Plant Tincture: recently dried herb, 1:5, 25%, 1-15 mL
•Infusion: finely chopped herb, 1:20, 90-120 mL

REFERENCES

Cook, WM. H. 1869. The Physiomedical Dispensatory.  Cincinnati: self-published.  Digitized version available from http://medherb.com/cook/home.htm.
Felter, HW and JU Lloyd. 1893. King's American Dispensatory. Digitized version available from http://www.ibiblio.org/herbmed/eclectic/kings/main.html.
Grieve, Maude. 1971. A Modern Herbal. New York: Dover Publications.
Mills, Simon and Kerry Bone. 2000. Principals and Practice of Phytotherapy. London: Churchill Livingstone
Newall, Carol A., Linda A. Anderson and J.D. Phillipson. 1996. Herbal Medicines: A Guide for Health-Care Professionals. London: The Pharmaceutical Press.
Weiss, Rudolf. 1988. Herbal Medicine. Translated by A.R. Meuss. Beaconsfield, England: Beaconsfield Publishers