Popular Herbal Teas and What Research Shows

Herbal teas, more accurately called tisanes or infusions, are made from flowers, leaves, roots and seeds of plants other than the tea plant, Camellia sinensis. Most contain no caffeine, they count toward daily fluid intake, and many people find them a calming ritual. Health claims are another matter. Some herbs have reasonable evidence for specific effects, others very little, and a few can interact with medicines. The profiles below summarize what is known about the most popular ones.

Chamomile

Traditionally used for: sleep and relaxation, and upset stomachs.

What the evidence says: small clinical trials suggest chamomile may modestly improve sleep quality in some groups, such as older adults and new mothers, and may ease mild anxiety symptoms, though studies often used extracts rather than tea and results are mixed.

Caution: people allergic to ragweed, daisies or related plants may react. Chamomile may interact with blood thinners such as warfarin.

Peppermint

Traditionally used for: digestion, bloating and headaches.

What the evidence says: enteric-coated peppermint oil capsules have reasonable evidence for relieving symptoms of irritable bowel syndrome, but peppermint tea itself has been studied much less. Many people find it soothing after meals.

Caution: peppermint can worsen heartburn and reflux in some people, because it relaxes the muscle between the stomach and esophagus.

Ginger

Traditionally used for: nausea and digestion.

What the evidence says: ginger is one of the better-studied herbal remedies, with research suggesting it can help with nausea in pregnancy and possibly after surgery and chemotherapy. Most studies used ginger capsules or powder, but fresh ginger tea is a common home remedy.

Caution: large amounts may interact with blood thinners. Pregnant people should discuss regular use with their doctor or midwife.

Hibiscus

Traditionally used for: a tart, refreshing drink, hot or iced.

What the evidence says: several small trials have found that drinking hibiscus tea daily for several weeks modestly lowered blood pressure in people with mildly elevated readings. It is not a substitute for prescribed treatment.

Caution: it may add to the effect of blood pressure medicines, and is generally advised against in pregnancy.

Rooibos

Traditionally used as: a naturally caffeine-free everyday tea from South Africa, with a mild, slightly sweet taste.

What the evidence says: rooibos contains antioxidants, but human studies on health effects are limited. It is a good caffeine-free swap for black tea, including with milk.

Lemon balm

Traditionally used for: calm and sleep.

What the evidence says: small studies, often combining lemon balm with other herbs such as valerian, suggest possible calming effects. Evidence for the tea alone is limited.

Caution: it may interact with thyroid medication and sedatives.

Valerian

Traditionally used for: sleep.

What the evidence says: research on valerian for insomnia has produced inconsistent results, and reviews have concluded the evidence is not strong enough to recommend it.

Caution: it can cause drowsiness and should not be combined with alcohol or sedative medicines.

Licorice root

Traditionally used for: sore throats and digestion, and for its naturally sweet flavor.

Caution: real licorice contains glycyrrhizin, which in large or regular amounts can raise blood pressure and lower potassium levels. People with high blood pressure, heart or kidney disease, and pregnant people should limit or avoid it.

Interactions and safety

"Natural" does not mean free of side effects. St. John's wort, sometimes sold as a tea, interacts with many medicines, including some birth control pills, antidepressants, blood thinners and HIV medicines, and can make them less effective. Herbal products are not regulated as strictly as medicines in many countries, so strength and purity can vary. Anyone who is pregnant or breastfeeding, taking prescription medicines, or preparing for surgery should check with a doctor or pharmacist before drinking medicinal herbs regularly.

Enjoying herbal tea

Use freshly boiled water and steep most herbal teas for five to ten minutes, covered, to keep aromatic oils in the cup. Experiment with blends, add fresh mint, ginger or citrus peel, or brew a large batch to chill for iced tea in summer. Enjoyed as a warm, caffeine-free drink, herbal tea is a pleasant habit even without any health claims.