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Thymus (Thymus vulgaris L.) — Encyclopedic Reference

1. Identity, Taxonomy, and Natural Source

Thymus vulgaris L. (commonly known as thyme or garden thyme) is scientifically classified within the family Lamiaceae, a diverse group of aromatic herbs that also includes mint, basil, and rosemary. Native to the Mediterranean region, particularly southern Europe, this small perennial herb thrives in sunny, well-drained locations and is characterized by its woody stems, small green-gray leaves, and delicate purple or white flowers. The plant typically grows to a height of 15–30 cm (6–12 inches) and is renowned for its compact, bushy growth habit.

The genus Thymus contains over 350 species, with Thymus vulgaris being the most widely cultivated for culinary and medicinal purposes. In the context of European herbal medicines regulation, thyme is the common name for the leaves and flowers of the plants Thymus vulgaris L. or Thymus zygis L. Other medicinally significant species include Thymus serpyllum (wild thyme) and Thymus zygis, both of which share overlapping chemistry and traditional applications with T. vulgaris.

The name thymus is derived from the Greek word thumos, which means "courage" or "to fumigate," reflecting its historical use in ancient cultures as a symbol of bravery and for purification rituals. The herb is cultivated in Eastern and Southern Europe and Northern Africa, as well as in the United States; India, Turkey, and Peru are leading exporters.

The leaves and flowers are the most important parts of the plant for herbal medicine. Thyme oil — formally designated Thymi aetheroleum — is the essential oil of Thymus vulgaris L. or Thymus zygis L., obtained by steam distillation from the fresh flowering above-ground parts.

1.1 Chemotypes

Several chemotypes have been identified in the essential oils of Thymus vulgaris, with carvacrol and thymol being the most frequent components across populations studied in countries including Algeria, Australia, Brazil, Croatia, Egypt, France, Iran, Italy, Jordan, Kenya, Morocco, Nepal, Romania, Serbia, South Africa, Spain, Tunisia, the United States, and Yemen. The predominant chemotype in commerce is the thymol-type, but carvacrol, linalool, geraniol, α-terpineol, and other oxygenated monoterpene chemotypes are also recognized. T. vulgaris shows aneuploidy, meaning the number of chromosomes varies in different plants of the same species, which contributes to the chemical diversity observed between populations.

2. Common Preparations and Dosage Forms

Preparations covered by major regulatory monographs include those obtained by drying and comminuting the leaves and flowers, by expressing the juice of the leaves and flowers, or as dry, liquid, and soft extracts.

The European Medicines Agency (EMA) Community Herbal Monograph formally recognizes the following defined preparation types for T. vulgaris and T. zygis herb: liquid extract (DER 1:1), extraction solvent ethanol 24% V/V; liquid extract (DER 1:1.16), extraction solvent glycerol 85%: ethanol 25%; liquid extract (DER 1:2–2.5), extraction solvent ammonia/glycerol/ethanol/water mixture; tincture (1:10 or 1:5), extraction solvent ethanol 70% V/V; soft extract (DER 5–8:1); liquid extract from fresh herb (DER 1:1.5–2.4), extraction solvent water (expressed juice); dry extract (DER 6–10:1), extraction solvent ethanol 70%; and dry extract (DER 1.6–2.4:1), extraction solvent ethanol 96%.

Additional preparations in common use include herbal infusions (teas), syrups, tinctures, steam-inhalation preparations, essential oil preparations for topical or aromatic application, and standardized-extract capsules. Herbal medicines containing thyme oil are usually available in liquid forms to be taken by mouth and in liquid or semi-solid forms to be applied to the skin.

Thymol and carvacrol are used for standardization in the German Pharmacopoeia, with the specification of 0.03% phenols calculated as thymol.

3. Traditional and Historical Use

3.1 Ancient Civilizations

The ancient Egyptians utilized thyme as part of their embalming process. The first recorded evidence for the medical uses of thyme dates back to the first century AD in Dioscorides' De materia medica and Pliny's Natural History.

Ancient Sumerian and Egyptian cultures used thyme to embalm the dead and for its medicinal properties; the Romans flavored cheese and alcoholic beverages with it, and burned it to ward off dangerous animals. When the Roman army conquered the land, they introduced thyme to the British Isles. Hippocrates, who lived around 460–370 BCE and is regarded as "the father of Western medicine," recommended thyme for respiratory diseases and conditions.

Ancient Greeks put thyme in their baths and burnt dried thyme as incense. Ancient Greeks strongly believed in the powers of thyme and used it in battle to restore physical strength and vitality, promote bravery, and relieve melancholy.

3.2 Medieval and Early Modern Europe

During the medieval period, thyme remained a staple in herbalism, cultivated by monks and herbalists in their gardens for its healing properties. It was commonly used to treat respiratory conditions like coughs and bronchitis and was believed to ward off nightmares when placed under a pillow. Thyme's antibacterial and antiseptic qualities made it invaluable for treating wounds and preventing infections, and it was often combined with other herbs to enhance its efficacy.

The tradition of giving thyme as a farewell gift to soldiers continued throughout the Middle Ages in England, where it also became a popular culinary spice. When the Black Death struck, thyme was used in many medicines as a treatment.

3.3 Documented Traditional Medical Uses

Thymus vulgaris is a medicinal and culinary herb from the Southern European region known for its anti-infective, cardioprotective, gastroprotective, anti-inflammatory, and immunomodulatory activities since the Egyptian era. Traditional preparations included herbal infusions (teas), poultices, gargles, steam inhalations, and topical applications. Flower shoots were used to treat mouth and skin infections, high blood pressure, heart problems, fluid retention, cystitis, digestive system disorders, rheumatism, and arthritis.

In more recent traditional practice, thyme has been used to treat bronchitis, laryngitis, whooping cough, sore throat, colds, pneumonia, asthma, diarrhea, and gastritis. Health Canada approves the traditional use of Thymus vulgaris in herbal medicine as an expectorant to help relieve the symptoms of bronchitis and mucus buildup of the upper respiratory tract.

The World Health Organization recognizes the antiseptic and wound-healing properties of thyme when applied locally to superficial skin wounds and for mouth irritations.

4. Phytochemistry: Key Constituents and Active Compounds

4.1 Volatile Essential Oil Components

Thymol is a phenol monoterpene naturally derived from cymene and is an isomer of carvacrol. It constitutes a significant portion (10%–64%) of the essential oils found in thyme (Thymus vulgaris L., Lamiaceae). The essential oil from T. vulgaris shows a high content of oxygenated monoterpenes (56.53%) and low contents of monoterpene hydrocarbons (28.69%), sesquiterpene hydrocarbons (5.04%), and oxygenated sesquiterpenes (1.84%). The predominant compound among the essential oil components is thymol (51.34%), while all other individual components constitute less than 19% each.

Additional essential oil constituents identified in T. vulgaris include p-cymene (a monoterpene hydrocarbon that serves as the biosynthetic precursor to thymol and carvacrol), γ-terpinene, linalool, borneol, α-terpineol, and 1,8-cineole. Reports indicate that the isomers carvacrol and thymol exhibit antioxidant, antifungal, and antibacterial effects, and these compounds contribute to the pharmacological effects of T. vulgaris essential oils.

4.2 Non-Volatile Phenolic and Flavonoid Constituents

The literature has indicated the presence of volatile oils, phenolic acids, terpenoids, flavonoids, saponins, steroids, tannins, alkaloids, and polysaccharides in the phytotherapy potential of T. vulgaris.

Among the phenolic acids, rosmarinic acid is the main component (882–1677 μg g⁻¹ fresh weight) in aqueous extracts of Thymus vulgaris. Apigenin and luteolin are the major flavonoids. Rosmarinic acid has been identified in all tested Thymus extracts, while luteolin-7-O-glucoside is detected in T. vulgaris extracts.

A growing body of evidence suggests that many Thymus species are a rich source of bioactive compounds including phenolic compounds such as rosmarinic acid, salvianolic acids, and luteolin glycosides, which may render them potential applications in a range of industrial fields.

Flavones including apigenin, luteolin, and 6-hydroxyluteolin and their glycosides are essential compounds in Thymus.

4.3 Key Active Molecules: Summary

• Thymol (2-isopropyl-5-methylphenol): A colorless crystalline monoterpene phenol; one of the most important dietary constituents in thyme species. For centuries it has been used in traditional medicine and has been shown to possess antioxidant, free radical scavenging, anti-inflammatory, analgesic, antispasmodic, antibacterial, antifungal, antiseptic, and antitumor activities.
• Carvacrol: An isomer of thymol, a monoterpene also referred to as cymophenol with the chemical formula C₆H₃(CH₃)(OH)C₃H₇. It shares many pharmacological properties with thymol.
• Rosmarinic acid: A hydroxycinnamic acid ester present as the dominant non-volatile phenolic acid, contributing substantially to antioxidant and anti-inflammatory activity.
• Apigenin and luteolin: Flavone compounds found consistently across Thymus extracts, with reported antispasmodic, anti-inflammatory, and antineoplastic properties.
• p-Cymene: A monoterpene hydrocarbon precursor and co-component of the essential oil, with mild analgesic and anti-inflammatory properties in preclinical models.

5. Mechanisms of Action

5.1 Antimicrobial Mechanisms

Thymol from thyme is one of a naturally occurring class of compounds known as biocides — substances that can destroy harmful organisms such as infectious bacteria. When used alongside other biocides such as carvacrol, thyme has strong antimicrobial properties, inhibiting the growth of microorganisms that can cause diseases.

The chemical configuration of terpene molecules such as thymol gives them hydrophobic properties and allows them to deposit on the lipophilic structures of microorganisms such as the plasma membrane; this deposition leads to increased permeability with a consequent loss of electrolytes essential to cell survival. Other action mechanisms include the inhibition of spore germination, fungal proliferation, and cell respiration.

5.2 Antifungal Mechanisms

Investigation of the mechanism of antifungal action showed that thyme essential oil and thymol interact with ergosterol, the primary fungal cell membrane sterol. These data indicate that the essential oil of T. vulgaris and thymol possess strong antifungal activity, which can be related to this interaction with ergosterol, supporting possible use in the treatment of mucormycosis. Studies on Thymus vulgaris essential oil and thymol have confirmed inhibitory action on Candida albicans growth.

5.3 Anti-inflammatory Mechanisms

In experimental carrageenan-induced pleurisy, thyme essential oil, carvacrol, and thymol significantly inhibited inflammatory edema. However, only thyme essential oil and carvacrol inhibited leukocyte migration. In an in vitro chemotaxis experiment, carvacrol inhibited leukocyte migration, whereas thymol exerted a potent chemoattractant effect.

The pain-reducing property of thyme is mainly attributed to thymol, which possesses the greatest anti-inflammatory potential among all reported constituents.

5.4 Bronchodilatory and Antispasmodic Mechanisms

Thyme is a herb with broncholytic and secretomotoric effects, and its activity on β₂-adrenoceptors has been demonstrated as a possible mechanism of action. Thymol and carvacrol exhibit a concentration-dependent antispasmodic effect in the rat trachea when stimulated by acetylcholine, K⁺, or Ba²⁺.

Regarding the flavone fraction, flavones were found to be non-competitive antagonists to specific agonists (acetylcholine, histamine, noradrenaline) and unspecific agonists (barium chloride). Inhibition of calcium-induced contractions on potassium-depolarized smooth muscles suggests inhibition of the availability of calcium for muscle contraction. Flavones induce relaxation of the carbachol-contracted tracheal strip without stimulation of the β-adrenoceptors.

Thymol (0–2 mM) exerts its relaxant effect on smooth muscle cells by opposing Ca²⁺ activation and ATP-dependent processes via its potent anti-spasmodic effect.

5.5 Antioxidant Mechanisms

Tested Thymus extracts possess DPPH (IC₅₀ = 3–6 μg/mL) and nitric oxide (IC₅₀ = 70–177 μg/mL) free radical scavenging activities, strong reducing properties (IC₅₀ = 11–15 μg/mL), ferrous ion chelating activity (IC₅₀ = 126–389 μg/mL), ability to inhibit lipid peroxidation (IC₅₀ = 34–80 μg/mL), and high total antioxidant capacities (238–294 mg ascorbic acid equivalents/g).

5.6 Anticancer Mechanisms (Preclinical)

Thymol and carvacrol upregulate pro-apoptotic genes (Bax, Bak, Bid, p53, and SIVA) while downregulating anti-apoptotic genes (Bcl-2, Bcl-xL, XIAP, and cIAP1), leading to apoptosis and cell cycle arrest at G0/G1 and G2/M phases. Thymol derivatives target breast cancer through PI3K/AKT/mTOR and NOTCH pathways. In lung cancer models, they act as SphK1 inhibitors in NSCLC cell lines H1299 and A549. Additionally, thymol exhibits anti-EGFR activity, while carvacrol modulates the HIF-1α/VEGF pathway in colorectal cancer models.

6. Scientific Evidence by Area of Use

6.1 Respiratory Tract: Cough, Bronchitis, and Expectorant Use

This is the most clinically documented therapeutic application of thyme, and the one with the strongest regulatory recognition.

Clinical trials, including randomized controlled studies, have shown that thyme extracts — often in combination with other herbs such as ivy (Hedera helix) — can help reduce cough frequency and improve bronchial mucus clearance in both adults and children with acute bronchitis. For example, a double-blind, randomized, placebo-controlled trial published in Phytomedicine (2006) found that a combination of thyme and ivy leaf extracts significantly reduced coughing fits compared to placebo.

A key prospective, double-blind, placebo-controlled multicentre clinical trial evaluated a fixed combination of dry extracts of thyme herb and primrose root in adults with acute bronchitis with productive cough. In the thyme-primrose combination group, a 50% reduction in coughing fits from baseline was reached approximately 2 days earlier compared to the placebo group. The symptoms of acute bronchitis improved rapidly in both groups, but regression was faster and the responder rates compared to placebo were higher under the thyme-primrose combination. Oral treatment of acute bronchitis with the thyme-primrose combination for approximately 11 days was superior to placebo in terms of efficacy.

Taking 30 drops of thyme and primrose root extract five times a day for 7 to 9 days appears to reduce acute bronchitis symptoms and shorten the duration of bronchitis compared with placebo.

In a comparative study involving patients with productive cough from uncomplicated respiratory infections, 60 patients were treated with thyme syrup (3 × 10 ml daily, n = 31) or a bromhexine preparation (n = 29) for 5 days. No significant difference was observed between thyme syrup and bromhexine in self-reported alleviation of complaints on days 2 and 5 of treatment. This suggests thyme's expectorant efficacy is at least comparable to the established mucolytic bromhexine in this patient group.

In a pediatric and adolescent population, preliminary clinical evidence suggests that taking a syrup containing thyme extract and ivy leaves for 10 days helps reduce symptoms, including coughing fits, in patients with acute bronchitis.

In a randomized triple-blind, placebo-controlled clinical trial specifically in children with asthma exacerbation, 60 children aged 5–12 years with asthma exacerbation were randomly divided into two groups. The intervention group (n = 30) received T. vulgaris powder at a dose of 20 mg/kg every 8 hours as a syrup alongside routine medical treatment for one week, and the control group received only routine medical treatment with placebo syrup, with clinical and spirometry data re-recorded at the end of the week.

The efficacy and safety of Thymus vulgaris L. liquid extract in the treatment of cough associated with cold is very well documented. The World Health Organization recognizes the use of thyme for coughs during colds or bronchitis, with the usual dose being 1 to 2 g of dried plant per cup of boiling water as an infusion, several times a day, or the equivalent in fresh herb.

Evidence strength: Moderate. Multiple randomized controlled trials support the use of thyme-containing preparations for cough and acute bronchitis, particularly in combination with ivy or primrose root. Most studies are short-term (7–14 days), involve combination herbal products, and have methodological limitations including lack of blinding in some cases. The EMA HMPC has recognized thyme preparations for "well-established use" for this indication.

6.2 Antimicrobial Activity

Thyme has long been known for its antiviral, antibacterial, antifungal, and antiseptic activities, in addition to remarkable disruption of microbial biofilms. The antimicrobial activity of thyme and thymol has been demonstrated across a broad spectrum of organisms in in vitro studies.

Thymol not only exhibits direct antifungal effects against Aspergillus fumigatus but also provides defense against corneal infections by inhibiting the LOX-1/IL-1β signaling cascade, which minimizes neutrophil and macrophage infiltration.

Evidence strength: Predominantly in vitro (laboratory). Direct human clinical evidence for systemic antimicrobial use is lacking. The regulatory recognition of thyme is for topical antiseptic and upper respiratory applications, not for systemic antimicrobial therapy.

6.3 Antifungal Activity

In vitro studies have shown that thyme essential oil and thymol at concentrations equal to MIC and 2 × MIC significantly reduced the dry mycelial mass of Rhizopus oryzae, with inhibition percentages of 55–66% for the essential oil and 61–67% for thymol, results that were greater than those observed for amphotericin B at the same relative concentrations. These results suggested that the substances evaluated inhibited normal mycelial development of R. oryzae at all concentrations tested.

Evidence strength: Preclinical (in vitro) only. No published clinical trials establishing antifungal efficacy in humans have been identified in the reviewed literature.

6.4 Anti-inflammatory and Analgesic Activity

Applications of constituents include antinociceptive, antispasmodic, and anti-inflammatory activities. The anti-inflammatory data derive primarily from animal models and in vitro studies rather than human clinical trials.

Evidence strength: Preclinical. In vitro and animal studies demonstrate inhibition of inflammatory mediators and edema. Robust human clinical trials specifically targeting inflammatory conditions are not available in the reviewed literature.

6.5 Antioxidant Activity

Thyme's multi-pharmacological properties include, but are not limited to, antioxidant, anti-inflammatory, and antineoplastic actions. The antioxidant activity of Thymus extracts has been widely characterized in vitro, with rosmarinic acid and flavones (luteolin, apigenin) identified as primary contributors.

Evidence strength: Preclinical (in vitro and some animal). Human clinical evidence for antioxidant benefits at physiologically achievable doses from dietary or supplemental thyme consumption is limited.

6.6 Anticancer Activity

In vitro studies confirm the efficacy of thymol and carvacrol against multiple cancer cell lines (MCF-7, HT-29, HeLa, PC-3, HepG2, HL-60), while in vivo animal models highlight their antiproliferative and antitumor effects. In the COVID-19 era, some thyme constituents were also investigated for their potential in viral binding.

Evidence strength: Preclinical only (cell lines and animal models). No human clinical trials on cancer treatment or prevention with thyme preparations have been identified in the reviewed literature. These findings should not be extrapolated to clinical use.

6.7 Gastrointestinal Applications

Applications in the gastrointestinal domain include gastroprotective and antispasmodic activities. The spasmolytic effects on smooth muscle have been studied ex vivo. Liquid thyme essential oil was most effective in decreasing basal contractility in ileum and colon; a solid essential oil formulation exerted relaxant activity on K⁺-depolarized intestinal smooth muscle comparable to the liquid essential oil.

Evidence strength: Predominantly preclinical (ex vivo and animal). Human clinical trials for thyme in gastrointestinal indications are sparse in the reviewed literature.

6.8 Oral Health

The World Health Organization recognizes the antiseptic properties of thyme for application to mouth irritations. Thymol is an established ingredient in certain commercial mouthwash formulations as an antiseptic agent, a use distinct from the supplemental/herbal applications discussed in this article.

Evidence strength: Moderate for topical oral antiseptic use of thymol specifically (based on long-standing pharmacopoeial recognition); evidence for herbal thyme preparations in oral health specifically is limited.

7. Regulatory Recognition and Monograph Status

The European Medicines Agency (EMA) Committee on Herbal Medicinal Products (HMPC) has reached scientific conclusions on the medicinal uses of thyme, and these conclusions are taken into account by EU Member States when evaluating applications for the licensing of herbal medicines containing thyme.

The German Commission E Monographs recognize thyme with two approved (positive) monographs: Thymi herba (Thymus vulgaris) and Serpylli herba (T. serpyllum).

Health Canada approves the traditional use of Thymus vulgaris in herbal medicine as an expectorant to help relieve the symptoms of bronchitis and mucus buildup of the upper respiratory tract.

The World Health Organization recognizes the use of thyme for coughs during colds or bronchitis.

8. Dosage Forms and Reported Dosages

The following dosages are as reported in authoritative sources and monographs and should be understood in the context of those sources only.

• Herbal infusion (tea): The German Commission E monograph recommends a cup (250 ml) of tea made from 1–2 g of the herb (approximately ¼–½ teaspoon) taken several times daily as needed for a cough. The WHO specifies 1 to 2 g of dried plant per cup of boiling water as an infusion, several times a day, or the equivalent in fresh herb.
• Fluid extract: A fluid extract of ¼–¾ teaspoon (1–4 ml) three times per day; alternatively, a tincture of ⅓–1 teaspoon (2–6 ml) three times per day.
• Thyme syrup (liquid extract): In a clinical study, patients with catarrh or bronchitis were treated daily with 15–30 ml of thyme syrup containing 97.6 mg of thyme fluid extract (2–2.5:1) per ml, for a period of 7–14 days (mean 7.9 days).
• Combination extract (drops): Taking 30 drops of thyme and primrose root extract five times a day for 7 to 9 days has been used in clinical studies for acute bronchitis.
• Pediatric use: In one randomized clinical trial in children with asthma exacerbation, T. vulgaris powder was administered at a dose of 20 mg/kg every 8 hours, prepared as a syrup, for one week. Most thyme preparations should only be used in adults and adolescents over the age of 12 years, but a few can also be used in children above 4 years of age.
• Topical preparations: Topical formulations recognized by Health Canada's natural health product monograph are prepared in a way equivalent to 50 mg of crude dried leaf and/or flowering herb tops per 1 ml or 1 g of finished product. Acceptable topical dosage forms include creams, gels, liquids, ointments, pastes, salves, solutions, and wipes.

9. Body Systems and Health Areas

• Respiratory system: From beneficial effects on the respiratory tract — including antispasmodic, expectorant, and bronchodilatory effects — thyme has been a consistently prominent subject for respiratory research.
• Gastrointestinal system: Gastroprotective, antispasmodic, and carminative activities have been reported, with antispasmodic effects on smooth muscle studied ex vivo.
• Immune and anti-infective: Reported pharmacological activities include antibacterial, antioxidant, anti-inflammatory, antiviral, and anti-cancerous activities.
• Cardiovascular system: Cardioprotective and antihypertensive activities have been mentioned in the phytotherapy literature.
• Nervous system / neuroprotection: Sedative, anticonvulsant, anti-amnesia, and antidepressant activities have been mentioned in preclinical reports.
• Oral cavity: The WHO recognizes antiseptic properties for application to superficial mouth irritations.
• Skin: Thymus vulgaris is considered helpful for skin problems such as oily skin, acne, dermatitis, and eczema, owing to its antioxidant and antimicrobial actions.

10. Safety Considerations and Drug Interactions

10.1 General Tolerability

Thyme is possibly safe when used as medicine in the short term. It might cause allergic reactions, dizziness, and stomach upset in some people. There is insufficient reliable information to know if thyme oil is safe to use as medicine or what the side effects might be.

Although numerous clinical trials provide evidence on the safe use of the liquid extract (DAB) and the expressed juice, the treatment of cough in children below 4 years of age requires supervision by a doctor.

10.2 Essential Oil Toxicity

The essential oil should be avoided in high doses both internally and externally as it can be toxic for both adults and children. Thyme oil is considered to be highly toxic at excessive doses; signs of toxicity include nausea, and based on animal studies may include tachypnea and hypotension. Endocrine effects of Thymus vulgaris in humans are unclear.

Mixtures of thymol and carvacrol appear to behave differently and be less toxic than thymol alone. Many essential oils of Thymus spp. are classified as GRAS (Generally Recognized as Safe) — not mutagenic, not embryotoxic in mice, and showing no skin irritation up to 2% in fragrance-sensitive volunteers. These results suggest that thyme oil (thymol/carvacrol rich) is less toxic than would be expected from individual toxicity data for thymol and carvacrol separately.

10.3 Allergic Reactions and Contraindications

Thyme is contraindicated for patients with a known sensitivity to the Lamiaceae family. Individuals with known cross-reactivity to other Lamiaceae herbs (e.g., oregano, mint, basil, lavender) should exercise caution. Allergic contact dermatitis from topical application of thyme oil has been reported in case reports.

10.4 Genitourinary and Other Anecdotal Concerns

Oral thyme has anecdotally been reported to exacerbate inflammation associated with urinary tract infections. Oral use of thyme or thyme oil has been associated with muscle weakness in anecdotal reports, although details are limited. Both of these reports are anecdotal in nature and are not substantiated by controlled clinical evidence in the reviewed literature.

10.5 Drug Interactions

A published case report described a clinically significant potential interaction between thyme and thyroid medication. A 52-year-old woman admitted to a toxicology department in January 2024 had a treatment for hypothyroidism consisting of levothyroxine sodium (150 µg daily), and she showed palpitations following the consumption of T. vulgaris tea to treat seasonal influenza. She reported that symptoms disappeared by reducing the doses of T. vulgaris. The probability score of the interaction was 6, indicating that a probable pharmacokinetic interaction may occur in patients with thyroid disorders taking levothyroxine sodium concomitantly with T. vulgaris.

This represents a single case report and requires further investigation; however, it identifies a plausible interaction of clinical relevance for patients receiving thyroid hormone replacement therapy.

10.6 Duration-of-Use Guidance

If symptoms persist longer than 1 week, a doctor or qualified healthcare practitioner should be consulted. Most thyme preparations are intended for adults and adolescents over 12 years; a few may be used in children above 4 years. If symptoms last longer than one week or worsen during use of the medicine, a doctor or qualified healthcare practitioner should be consulted.

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