Herb-Drug Interactions: Thyme

Thymus vulgaris L. (Lamiaceae)

Synonym(s) and related species

Common thyme, French thyme, Garden thyme, Rubbed thyme.

Thymus aestivus Reut. ex Willk., Thymus ilerdensis Gonz. Frag, ex Costa., Thymus x valentinus Rouy., Thymus webbianus Rouy, Thymus welwitschii Boiss. subsp ilerdensis (Gonz. Frag, ex Costa) Nyman, and Thymus zygis L. are also used.

Not to be confused with wild thyme, which is Thymus serpyllum L.

Pharmacopoeias

Thyme (British Ph 2009, European Ph 2008); Thyme Oil (British Ph 2009, European Ph 2008); Thymol (British Ph 2009, European Ph 2008); Wild Thyme (British Ph 2009, European Ph, 6th ed., 2008 and Supplements 6.1, 6.2, 6.3 and 6.4).

Constituents

The major non-volatile constituents of thyme are the flavonoids including apigenin, eriodictyol, luteolin, naringenin and others. Other non-volatile constituents include caffeic acid, rosmarinic acid, saponins and tannins. The oil contains up to 70% thymol, with carvacrol, p-cymene, linalool, alpha-terpineol and thujan-4-ol. Other species contain similar constituents, although some varieties contain less thymol and more of the other components.

Use and indications

Thyme is used traditionally as a carminative, spasmolytic and antimicrobial, particularly for the respiratory system. Thymol is widely used in dentistry as a mouthwash, but it is toxic in high doses and should not be taken internally or applied externally in large amounts. Thyme is commonly used as a flavouring ingredient in foods.

Pharmacokinetics

An aqueous extract of thyme has been identified as a potent inhibitor of several cytochrome P450 isoenzymes, namely CYP2C9, CYP2C19, CYP2D6 and CYP3A4, in an in vitro study. However, these findings should be interpreted with caution, as the study also found St John’s wort to be a CYP3A4 inhibitor, whereas clinically it is a CYP3A4 inducer.

For information on the pharmacokinetics of individual flavonoids present in thyme, see under flavonoids.

Interactions overview

No interactions with thyme found. Note that thyme is commonly used as a flavouring ingredient in foods.

For information on the interactions of individual flavonoids present in thyme, see under flavonoids.