Aside from its culinary value, thyme is used in traditional medicine to treat a variety of health conditions. Its main compound, thymol, is attributed with antimicrobial, antifungal, antioxidant and antitussive properties. In fact, thyme tea is considered an excellent remedy for cough associated with bronchitis and upper respiratory tract infections. However, there are a few thyme tea side effects to consider.
According to a study published in the April 2006 issue of "Contact Dermatitis," you should avoid drinking thyme tea if you have a known sensitivity to plants in the mint family of Lamiaceae. The list of members belonging to this family is long, but some common plants include rosemary, basil, catmint, hyssop, oregano and celery. Juan R. Avila, author of “Professional's Handbook of Complementary and Alternative Medicines,” advises to avoid thyme if you have an allergy to grass. If you experience chest pain, shortness of breath, tightening of the throat, skin rash or swelling of the joints after drinking thyme tea, seek immediate medical attention.
According to authors Joanne Barnes and Mark Blumenthal, high doses of thyme may produce negative side effects. Some of the most commonly reported side effects associated with thyme include heartburn, nausea, vomiting, stomach upset, diarrhea, headache and dizziness. In addition, the volatile oils present in thyme leaves may promote slowed heart rate and rapid breathing in certain individuals.
Avila also cautions against ingesting thyme or tea made from thyme leaves if you have a history of heart disease, peptic ulcers or other gastrointestinal disorders.
German researchers have found that one species of thyme, Thymus serpyllum, may have an adverse effect on the thyroid. The research team, who published their findings in the June 1982 issue of "Planta Medica," reported that thyme, as well as other members of the mint family, impacted levels of a thyroid-stimulating hormone secreted by the pituitary gland in rats. In theory, this means that drinking thyme tea on a regular basis could result in a decrease of thyroid hormones in people as well. In addition, you should avoid thyme tea if you are undergoing thyroid replacement therapy or taking anti-thyroid medications.
Pregnancy and Lactation
There isn’t enough scientific information to establish the safety of thyme for pregnant women, and it is not known if thyme compounds pass into breast milk. However, it should be noted that thyme has historically been used to promote menstruation, which means there may be a risk of spontaneous abortion involved. As a general rule, pregnant and nursing women should not consume herbal teas or supplements without the guidance of a health care practitioner.