Thyme (Thymus vulgaris L.), Thymol Dosing and Safety

safety

Allergies

Avoid in individuals with a known allergy or hypersensitivity to thyme, its constituents, members of the Lamiaceae (mint) family, or to rosemary (Rosmarinus officinalis).
Cross-reactions to birch pollen, celery, oregano, and other species in the Lamiaceae or Labiatae (mint) families may occur. Symptoms of allergy may include nausea, vomiting, runny nose, severe itching, swelling under the skin, difficulty swallowing, altered voice, low blood pressure, contact dermatitis, inflammation of lung cells, and progressive respiratory difficulty. Occupational asthma has been reported.

Side Effects and Warnings

Although not well studied in humans, thyme flowers and leaves appear to be safe in culinary and in limited medicinal use. Caution is warranted with the use of thyme oil, which should not be taken by mouth and should be diluted when applied on the skin, due to potentially toxic effects.
Side effects of thyme taken by mouth may include headache, dizziness, low blood pressure, slowed heart rate, heartburn, nausea, vomiting, diarrhea, gastrointestinal irritation, muscle weakness, and worsened inflammation associated with urinary tract infections.
Taking thyme oil by mouth may cause seizure, coma, cardiac arrest, or respiratory arrest. High doses of thyme or thyme oil may cause rapid breathing. Inflammation of the eye and nasal mucosa has also been reported with exposure to thyme dust. Halothane hepatitis (liver disease) may be partially due to the thymol in the halothane. Thyme extract may alter levels of certain blood cells.
Thyme may lower blood sugar levels. Caution is advised in patients with diabetes or hypoglycemia and in those taking drugs, herbs, or supplements that affect blood sugar. Blood glucose levels may need to be monitored by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.
Thyme may increase the risk of bleeding. Caution is advised in patients with bleeding disorders or those taking drugs that may increase the risk of bleeding. Dosing adjustments may be necessary.
Use cautiously in patients with gastrointestinal irritation or peptic ulcer disease.
Thyme may cause low blood pressure. Caution is advised in patients with low blood pressure and in those taking drugs, herbs, or supplements that lower blood pressure.
Drowsiness or sedation may occur. Use caution if driving or operating heavy machinery or if taking sedatives or CNS depressants.
Caution is advised when thyme is used in medicinal amounts in women who are pregnant or trying to become pregnant, due to the possibility of negative effects on fertility and/or potential to stimulate abortion.
Use cautiously in patients with thyroid disorders, hormonal disorders or at risk for hormone imbalances, or in patients taking agents for these conditions.
Use cautiously in patients taking agents metabolized by the liver's cytochrome P450 system, ciprofloxacin, salicylate-containing agents, or topical agents.
Avoid in individuals with a known allergy or hypersensitivity to thyme, its constituents, members of the Lamiaceae (mint) family, or to rosemary (Rosmarinus officinalis).
Avoid use on the skin in areas of skin breakdown or injury, or in atopic patients.

Pregnancy and Breastfeeding

Medicinal levels of thyme are not recommended in pregnant or breastfeeding women, due to a lack of available scientific evidence. Thyme may act as an emmenagogue (promoting menstruation) and abortifacient (promoting abortion).

dosing

Adults (18 years and older)

There is no proven safe or effective dose for thyme or thymol in adults. Thyme has been taken by mouth as a tea, liquid extract, and tincture. On the skin, ointments and compresses have been used. Thyme oil is considered to be highly toxic and should not be taken internally.
For cough, syrup of thyme has been taken by mouth for five days.
For upper respiratory tract infection, traditional uses include drinking tea, made by steeping 1-2 grams of dried herb in 150 milliliters of boiling water for 10 minutes, several times daily as needed for symptom alleviation. Other examples include 1-2 grams of extract in fluid or one cup of water up to three times daily; 20-40 drops of liquid extract (1:1 weight/volume of fresh leaf or 1:4 of dried leaf) three times daily in juice; or 40 drops of tincture (1:10 in 70% ethanol) up to three times daily.
For agitation in dementia, thyme oil placed on an absorbent fabric sachet and pinned near the collarbone every three hours for two weeks has been used.

There is no proven safe or effective dose for thyme in children.

interactions

Interactions with Drugs

Thyme may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants (blood thinners) such as warfarin (Coumadin®) or heparin, antiplatelet drugs such as clopidogrel (Plavix®), and nonsteroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®).
Thyme may lower blood sugar levels. Caution is advised when using medications that may also lower blood sugar. Patients taking insulin or drugs for diabetes by mouth should be monitored closely by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.
Thyme may interfere with the way the body processes certain drugs using the liver's cytochrome P450 enzyme system. As a result, the levels of these drugs may be increased in the blood and may cause increased effects or potentially serious adverse reactions. Patients using any medications should check the package insert and speak with a qualified healthcare professional, including a pharmacist, about possible interactions.
Thyme may cause low blood pressure. Caution is advised in patients taking drugs that lower blood pressure.
Thyme may increase the amount of drowsiness caused by some drugs. Examples include benzodiazepines such as lorazepam (Ativan®) or diazepam (Valium®), barbiturates such as phenobarbital, narcotics such as codeine, some antidepressants, central nervous system depressants, sedatives, and alcohol. Caution is advised while driving or operating machinery.
Thyme may also interact with 5-fluorouracil, Alzheimer's agents, analgesics (pain relievers), antibiotics, anticancer agents, antifungals, anti-inflammatory agents, antiprotozoals, antispasmodic agents, antithyroid agents, antivirals, bethanechol, bosentan, caffeine, cardiovascular agents, cholesterol-lowering agents, cholinesterase inhibitors, cough medications, dental agents, drugs that affect GABA, drugs used for osteoporosis, hormonal agents, hydrocortisone, hydrophilic drugs, immune suppressants, ketoprofen, muscle relaxants, naproxen, nitrendipine, piroxicam, salicylates, tamoxifen, thyroid hormones, and vasodilators (agents that increase dilation of blood vessels).

Interactions with Herbs and Dietary Supplements

Thyme may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.
Thyme may lower blood sugar levels. Caution is advised when using herbs or supplements that may also lower blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.
Thyme may interfere with the way the body processes certain herbs or supplements using the liver's cytochrome P450 enzyme system. As a result, the levels of other herbs or supplements may become too high in the blood. It may also alter the effects that other herbs or supplements possibly have on the P450 system.
Thyme may cause low blood pressure. Caution is advised in patients taking herbs and supplements that lower blood pressure.
Thyme may increase the amount of drowsiness caused by some herbs or supplements such as central nervous system depressants and sedatives.
Thyme may also interact with agar, Alzheimer's herbs and supplements, analgesics (pain relievers), antibacterials, anticancer herbs and supplements, antifungals, anti-inflammatory herbs and supplements, antioxidants, antiparasitics, antispasmodics, antivirals, anxiolytics, basil, caffeine, cardioactive herbs and supplements, carrageenan, cholesterol-lowering herbs and supplements, dental herbs and supplements, fatty acids, fenugreek, grape juice, herbs and supplements that affect GABA, herbs and supplements that affect the thyroid, herbs and supplements used for osteoporosis, herbs and supplements used for cough, hormonal herbs and supplements, hydrophilic herbs and supplements, immune suppressants, iron, ivy, muscle relaxants, oregano, potato, probiotics, rice, rosemary, sage, salicylate-containing herbs and supplements, shrimp, soy sauce, sunflower oil, vasorelaxants (herbs and supplements that increase dilation of blood vessels), vitamin E, and xanthum gum.