Thyme

The medicine is the dried leaf and flowering top. Western herbalism describes thyme as a warming, drying aromatic, with antimicrobial, expectorant and antispasmodic actions.

It is given for cold, damp chest complaints where mucus is thick and hard to clear: cough, bronchitis, chest congestion and sore throat. It is used for the loose, heavy, productive cough, where a soothing demulcent herb would be chosen for a dry, raw one.

The same warming, drying character extends its use to sluggish digestion and to urinary tract infections. It is taken as an infusion, a syrup or a steam inhalation.

The European Medicines Agency accepts thyme herb and thyme oil as traditional medicines for productive cough associated with colds ^{25,26Reference 25European Medicines Agency · 2013ReviewCommunity herbal monograph on Thymus vulgaris L. and Thymus zygis L., herba (EMA/HMPC/342332/2013) — regulatory monograph. https://www.ema.europa.eu/en/documents/herbal-monograph/final-community-herbal-monograph-thymus-vulgaris-l-and-thymus-zygis-l-herba_en.pdfView study →Reference 26European Medicines Agency · 2020ReviewEuropean Union herbal monograph on Thymus vulgaris L., Thymus zygis L., aetheroleum, revision 1 (EMA/HMPC/59032/2017) — regulatory monograph. https://www.ema.europa.eu/en/documents/herbal-monograph/final-european-union-herbal-monograph-thymus-vulgaris-l-thymus-zygis-l-aetheroleum-revision-1_en.pdfView study →}.

Household European practice used thyme for coughs and chest infections, for digestive complaints, and as a protective herb during outbreaks of infectious disease.

Steam inhalations over a bowl, thyme wines and honey-based syrups were the standard household forms for chest illness.

In its native Mediterranean, thyme is a daily culinary herb, a digestive, and a preservative that slows food spoilage.

A 2015 systematic review and meta-analysis of herbal medicines for cough in upper respiratory infections pooled four trials of ivy, primrose and thyme preparations. It found strong evidence of benefit (risk ratio 1.40, 95% CI 1.23–1.60) ^{1Reference 1Wagner et al. · 2015Meta-analysisHerbal Medicine for Cough: a Systematic Review and Meta-AnalysisView study →}.

Two double-blind, placebo-controlled trials in adults with acute bronchitis and productive cough each enrolled 361 people for 11 days. With a thyme–ivy syrup (Bronchipret), daytime coughing fits fell by 68.7% against 47.6% on placebo ^{3Reference 3Kemmerich et al. · 2006RCTEfficacy and tolerability of a fluid extract combination of thyme herb and ivy leaves vs placebo in acute bronchitis — randomised, double-blind, placebo-controlled trialView study →}. With a thyme–primrose tablet, they fell by 67.1% against 51.3% ^{2Reference 2Kemmerich · 2007RCTEvaluation of efficacy and tolerability of a fixed combination of dry extracts of thyme herb and primrose root in adults with acute bronchitis — double-blind, placebo-controlled, randomised multicentre trialView study →}. In both trials a 50% reduction in coughing fits came about two days sooner, and side effects were no more common than on placebo ^{2,3Reference 2Kemmerich · 2007RCTEvaluation of efficacy and tolerability of a fixed combination of dry extracts of thyme herb and primrose root in adults with acute bronchitis — double-blind, placebo-controlled, randomised multicentre trialView study →Reference 3Kemmerich et al. · 2006RCTEfficacy and tolerability of a fluid extract combination of thyme herb and ivy leaves vs placebo in acute bronchitis — randomised, double-blind, placebo-controlled trialView study →}.

A 2024 triple-blind trial gave 60 children aged 5–12 with asthma flare-ups either thyme powder syrup (20 mg/kg every 8 hours) or placebo syrup, alongside usual treatment, for a week. Cough on exertion and FEV1 improved more with thyme, while wheezing and breathlessness did not differ ^{4Reference 4Eskandarpour et al. · 2024RCTThymus vulgaris ameliorates cough in children with asthma exacerbation — randomised, triple-blind, placebo-controlled clinical trialView study →}.

In an uncontrolled study of 730 people with acute cough in 305 German pharmacies, a thyme–ivy extract (BNO 1200) was followed by marked improvement in symptoms and was well tolerated ^{5Reference 5Kardos et al. · 2021ObservationalEffectiveness and tolerability of the thyme/ivy herbal fluid extract BNO 1200 for acute cough — observational pharmacy-based studyView study →}.

A 2025 open-label trial in 325 adults with acute bronchitis compared an ivy extract alone with thyme–ivy and thyme–primrose drops. The ivy extract was non-inferior to both combinations and better than the thyme–ivy drops on the bronchitis severity score ^{6Reference 6Kardos et al. · 2025RCTEfficacy and Safety of a Single Ivy Extract Versus Two Herbal Extract Combinations in Acute Bronchitis — multi-center, randomised, open-label clinical trialView study →}.

Gap: the trials test thyme combined with ivy or primrose — there is no comparably powered placebo-controlled trial of a thyme monopreparation, so the herb’s own contribution is inferred, not measured.

Thyme’s traditional use as an antiseptic matches a large in vitro literature. A 2015 review summarised the antibacterial activity of Thymus species, whose oils are rich in thymol, carvacrol, p-cymene and terpinene ^{14Reference 14Nabavi et al. · 2015ReviewPlants belonging to the genus Thymus as antibacterial agents: from farm to pharmacy — reviewView study →}.

The oil of an Ethiopian species, Thymus serrulatus, was active against Staphylococcus aureus and Candida albicans in agar tests, with a smaller effect on MRSA ^{12Reference 12Rehman et al. · 2021In vitroTracheal relaxant and antimicrobial effects of the essential oil of an Ethiopian thyme species — in vitro / ex vivoView study →}.

In a fermented dairy food, added thyme suppressed yeasts and moulds while the lactic acid bacteria survived ^{21Reference 21Altun et al. · 2026In vitroFunctional enhancement of fermented dairy-based tarhana with Thymus vulgaris: phytochemical characterisation and in vitro antioxidant/antidiabetic potentialView study →}.

These are culture-dish and food results at oil-level concentrations, whereas thyme is used clinically as a tea, tincture or diluted gargle. No controlled trial shows thyme clearing an infection in people.

Gap: essentially all antibacterial data are in vitro or in food models; there is no clinical antimicrobial trial at drinkable doses.

In rats with LPS-induced bronchoalveolitis, a thyme–ivy syrup given by mouth reduced leukocytes in the lungs and blood and reduced goblet-cell numbers. In vitro it blocked leukotriene release from human neutrophils and monocytes and inhibited 5-lipoxygenase ^{7Reference 7Seibel et al. · 2015AnimalBronchipret syrup containing thyme and ivy extracts suppresses bronchoalveolar inflammation and goblet-cell hyperplasia in experimental bronchoalveolitis — rat in vivo studyView study →}.

A thyme–primula combination reduced lung inflammation and mucin production in rats, and mucus production in human airway cells ^{8Reference 8Seibel et al. · 2018In vitroAnti-inflammatory and mucus-regulatory activities of a fixed combination of thyme and primula extracts — in vivo and in vitroView study →}.

Isolated thymol, given by mouth at 5–20 mg/kg, reduced Klebsiella-induced lung injury in mice and improved bacterial clearance ^{16Reference 16Amarni et al. · 2026AnimalThymol attenuates Klebsiella pneumoniae-induced lung injury — in vivo mouse and in silico studyView study →}. A thyme leaf extract protected mice against lung injury from fine particulate matter, reducing inflammation and excess mucus ^{17Reference 17Lee et al. · 2025AnimalProtective effects of thyme leaf extract against particulate-matter-induced pulmonary injury in mice — animal modelView study →}.

In people, a single thyme–primrose tablet containing 1.08 mg of thymol produced no detectable thymol in the blood. Its metabolite thymol sulfate was measurable in plasma for up to 41 hours ^{13Reference 13Kohlert et al. · 2002Systemic availability and pharmacokinetics of thymol in humans — clinical pharmacokinetic trialView study →}.

No human trial has measured an anti-inflammatory endpoint for thyme alone.

In isolated rat trachea, thyme extract inhibited contraction caused by endothelin. Thymol had no part in this effect ^{11Reference 11Engelbertz et al. · 2008AnimalThyme extract, but not thymol, inhibits endothelin-induced contractions of isolated rat trachea — ex vivoView study →}. A small part of thyme’s relaxant effect on the trachea acts through β2 receptors ^{11Reference 11Engelbertz et al. · 2008AnimalThyme extract, but not thymol, inhibits endothelin-induced contractions of isolated rat trachea — ex vivoView study →}.

Extracts with normal or very low thymol content were compared. Thymol and carvacrol relaxed rat trachea and increased mucus clearance in mice, and the normal extract was more effective. Extracts almost free of volatile oil were still active in most models, so other compounds contribute ^{10Reference 10Begrow et al. · 2010Impact of thymol in thyme extracts on antispasmodic action and ciliary clearance — animal ex vivo studyView study →}.

In airway tissue grown from people with COPD, a thyme extract increased cilia beat frequency ^{9Reference 9Nabissi et al. · 2018In vitroThyme extract increases mucociliary-beating frequency in primary cell lines from COPD patients — in vitroView study →}.

The essential oil of Thymus serrulatus relaxed guinea-pig trachea in a way consistent with calcium-channel blockade and phosphodiesterase inhibition ^{12Reference 12Rehman et al. · 2021In vitroTracheal relaxant and antimicrobial effects of the essential oil of an Ethiopian thyme species — in vitro / ex vivoView study →}.

All the direct airway-relaxation evidence is from isolated tissue or cells; no human lung-function trial of thyme as a bronchodilator exists.

Adding thyme to a fermented dairy food raised its phenolic content and its DPPH and ABTS radical scavenging, in proportion to the amount added ^{21Reference 21Altun et al. · 2026In vitroFunctional enhancement of fermented dairy-based tarhana with Thymus vulgaris: phytochemical characterisation and in vitro antioxidant/antidiabetic potentialView study →}.

In mice, a thyme leaf extract reduced oxidative stress in lung injury from fine particulate matter ^{17Reference 17Lee et al. · 2025AnimalProtective effects of thyme leaf extract against particulate-matter-induced pulmonary injury in mice — animal modelView study →}. An extract of a different species, Thymus linearis, protected rats against drug-induced heart injury ^{23Reference 23Arshad et al. · 2022AnimalCardioprotective potential of Thymus linearis against induced myocardial ischemia — rat in vivo studyView study →}.

The compounds involved include rosmarinic acid, luteolin and thymol ^{21Reference 21Altun et al. · 2026In vitroFunctional enhancement of fermented dairy-based tarhana with Thymus vulgaris: phytochemical characterisation and in vitro antioxidant/antidiabetic potentialView study →}. No human study has measured an antioxidant outcome for thyme.

The essential oil of Thymus serrulatus was active against Candida albicans in agar tests ^{12Reference 12Rehman et al. · 2021In vitroTracheal relaxant and antimicrobial effects of the essential oil of an Ethiopian thyme species — in vitro / ex vivoView study →}.

Pure carvacrol combined with quercetin cut the biomass of Candida albicans biofilms from a catheter by about 82% at half the inhibitory concentration in a 2026 study ^{15Reference 15Kannan et al. · 2026In vitroQuercetin and carvacrol act synergistically to inhibit Candida albicans biofilms in vitro via membrane disruption and oxidative stressView study →}.

Gap: activity is in vitro and formulation-dependent; there is no controlled clinical trial of thyme for a human fungal infection, and the whole-herb preparations most people use are far more dilute than the tested oils.

Thymol is an ingredient of essential-oil mouthrinses. A 2015 meta-analysis of 29 six-month trials found such a rinse, added to brushing, reduced gingivitis by 16% and plaque by 27.7% ^{22Reference 22Araujo et al. · 2015Meta-analysisMeta-analysis of the effect of an essential-oil-containing mouthrinse on gingivitis and plaqueView study →}.

The rinse is a fixed four-ingredient product (thymol with eucalyptol, menthol and methyl salicylate), so the result applies to that product rather than to thyme preparations.

Gap: the human data are for a multi-ingredient thymol rinse, not for thyme herb.

Tolerance. In the two large bronchitis trials, side effects were no more frequent or severe on thyme combinations than on placebo, and there were no serious adverse events ^{2,3Reference 2Kemmerich · 2007RCTEvaluation of efficacy and tolerability of a fixed combination of dry extracts of thyme herb and primrose root in adults with acute bronchitis — double-blind, placebo-controlled, randomised multicentre trialView study →Reference 3Kemmerich et al. · 2006RCTEfficacy and tolerability of a fluid extract combination of thyme herb and ivy leaves vs placebo in acute bronchitis — randomised, double-blind, placebo-controlled trialView study →}. In a pharmacy study of 730 people, 98% rated tolerability good or very good ^{5Reference 5Kardos et al. · 2021ObservationalEffectiveness and tolerability of the thyme/ivy herbal fluid extract BNO 1200 for acute cough — observational pharmacy-based studyView study →}. The European monograph lists stomach upset as a possible side effect ^{25Reference 25European Medicines Agency · 2013ReviewCommunity herbal monograph on Thymus vulgaris L. and Thymus zygis L., herba (EMA/HMPC/342332/2013) — regulatory monograph. https://www.ema.europa.eu/en/documents/herbal-monograph/final-community-herbal-monograph-thymus-vulgaris-l-and-thymus-zygis-l-herba_en.pdfView study →}.

Allergy. Thyme should not be used by people allergic to it or to other plants of the mint family (Lamiaceae) ^{25Reference 25European Medicines Agency · 2013ReviewCommunity herbal monograph on Thymus vulgaris L. and Thymus zygis L., herba (EMA/HMPC/342332/2013) — regulatory monograph. https://www.ema.europa.eu/en/documents/herbal-monograph/final-community-herbal-monograph-thymus-vulgaris-l-and-thymus-zygis-l-herba_en.pdfView study →}.

Children. The European monograph does not recommend most thyme preparations, including the tea, under 12 years because data are lacking. Two liquid preparations are allowed from age 4 ^{25Reference 25European Medicines Agency · 2013ReviewCommunity herbal monograph on Thymus vulgaris L. and Thymus zygis L., herba (EMA/HMPC/342332/2013) — regulatory monograph. https://www.ema.europa.eu/en/documents/herbal-monograph/final-community-herbal-monograph-thymus-vulgaris-l-and-thymus-zygis-l-herba_en.pdfView study →}.

Essential oil. The oil is taken by mouth only in small amounts, 0.2–0.25 mL at a time, and is not recommended by mouth or on the skin under 18. Rubs contain up to 10% oil. It should not be applied to the face, particularly near the nose, of babies and children under 2, because of the risk of laryngospasm ^{26Reference 26European Medicines Agency · 2020ReviewEuropean Union herbal monograph on Thymus vulgaris L., Thymus zygis L., aetheroleum, revision 1 (EMA/HMPC/59032/2017) — regulatory monograph. https://www.ema.europa.eu/en/documents/herbal-monograph/final-european-union-herbal-monograph-thymus-vulgaris-l-thymus-zygis-l-aetheroleum-revision-1_en.pdfView study →}. Skin irritation and allergic reactions have been reported ^{26Reference 26European Medicines Agency · 2020ReviewEuropean Union herbal monograph on Thymus vulgaris L., Thymus zygis L., aetheroleum, revision 1 (EMA/HMPC/59032/2017) — regulatory monograph. https://www.ema.europa.eu/en/documents/herbal-monograph/final-european-union-herbal-monograph-thymus-vulgaris-l-thymus-zygis-l-aetheroleum-revision-1_en.pdfView study →}. The neat oil should not be swallowed or applied to the skin undiluted.

Warning signs. Breathlessness, fever or coloured sputum during a cough need a doctor’s assessment ^{25Reference 25European Medicines Agency · 2013ReviewCommunity herbal monograph on Thymus vulgaris L. and Thymus zygis L., herba (EMA/HMPC/342332/2013) — regulatory monograph. https://www.ema.europa.eu/en/documents/herbal-monograph/final-community-herbal-monograph-thymus-vulgaris-l-and-thymus-zygis-l-herba_en.pdfView study →}.

Interactions. No interactions have been reported in people ^{25,26Reference 25European Medicines Agency · 2013ReviewCommunity herbal monograph on Thymus vulgaris L. and Thymus zygis L., herba (EMA/HMPC/342332/2013) — regulatory monograph. https://www.ema.europa.eu/en/documents/herbal-monograph/final-community-herbal-monograph-thymus-vulgaris-l-and-thymus-zygis-l-herba_en.pdfView study →Reference 26European Medicines Agency · 2020ReviewEuropean Union herbal monograph on Thymus vulgaris L., Thymus zygis L., aetheroleum, revision 1 (EMA/HMPC/59032/2017) — regulatory monograph. https://www.ema.europa.eu/en/documents/herbal-monograph/final-european-union-herbal-monograph-thymus-vulgaris-l-thymus-zygis-l-aetheroleum-revision-1_en.pdfView study →}. In laboratory tests, thyme was among the spices that most strongly inhibited drug-metabolising enzymes, including CYP3A4 ^{28Reference 28Foster et al. · 2003In vitroIn vitro inhibition of human cytochrome P450-mediated metabolism of marker substrates by natural products — in vitroView study →}.