Comparison guide

Herbal teas: which ones actually work?

Herbal teas are infusions of plants other than Camellia sinensis (green, black, white and oolong tea have their own guide). Most trials behind these herbs used concentrated extracts or capsules, not a cup of tea, so a herb's evidence rating rarely carries over to the bag in your cupboard. The exceptions are hibiscus, tested as a brewed drink for blood pressure, and passionflower, tested as a bedtime tea.

The options, compared

Option	Evidence	Best for	The honest note
Hibiscus	Moderate evidence	Mildly raised blood pressure	The one tea here whose brewed drink has consistent trial support: about 2–3 g of dried calyces per cup, one to three cups a day, lowered systolic pressure by roughly 4–7 mmHg. It adds to blood pressure drugs and should be avoided in pregnancy.	View
Ginger	Moderate evidence	Nausea	Solid evidence for nausea in pregnancy and after surgery, but the trials used 1,000–1,500 mg/day of dried root in capsules, more than a cup of tea usually gives. Ginger tea is a reasonable first step; the joint-pain claims are weak.	View
Chamomile	Moderate evidence	Anxiety, as an extract	The anxiety evidence comes from an extract standardised to 1.2% apigenin at up to 1,500 mg/day; a tea bag delivers far less. As a sleep aid it is much weaker than its reputation. Avoid it with ragweed allergy or warfarin.	View
Peppermint Oil (Enteric-Coated)	Strong evidence	IBS, as capsules, not tea	The strong IBS evidence is for enteric-coated peppermint oil capsules taken before meals, not for the tea. Peppermint relaxes the lower oesophageal sphincter, so both tea and oil can worsen reflux.	View
Peppermint Tea	Limited evidence	Taste, not proven for IBS	Trials of the tea itself are almost absent; one small trial found a short-term boost in cognition. It is caffeine-free and well tolerated, but can worsen reflux.	View
Lemon Balm	Limited evidence	Feeling a little calmer	Small, inconsistent trials suggest it raises self-rated calmness; tea from 1.5–4.5 g of dried leaf is not comparable to the extract doses studied. Very safe, but its drowsiness adds to alcohol and sedatives.	View
Passionflower	Limited evidence	Bedtime, with tea-based data	One of the few herbs tested as a tea: 2 g of dried herb brewed before bed gave a small improvement in self-rated sleep in a small trial. It can cause drowsiness and dizziness; avoid it in pregnancy.	View
Fennel	Limited evidence	Period pain, as an extract	Small trials found fennel extract eased menstrual pain about as well as mefenamic acid, but certainty is low, and seed tea (1–3 g per cup) is a much lower dose. Do not give it to infants for colic without paediatric advice.	View
Rooibos Extract	Limited evidence	A caffeine-free daily drink	Pleasant and caffeine-free, but the health effects seen in small human studies, after about six cups a day for six weeks, were modest and not consistently replicated. Drink it for the taste, not as a treatment.	View
Yerba Mate	Limited evidence	Caffeine, drunk warm, not scalding	Its effects are mostly those of caffeine, with no convincing weight-loss data. Heavy, very hot drinking is consistently linked to oesophageal cancer: let it cool below about 60–65 °C and prefer air-dried leaf.	View
Guayusa	Limited evidence	Another caffeine source	A cup gives roughly 50–90 mg of caffeine and behaves like caffeine in two small trials; the claim of a smoother energy is not established. Count it in your daily caffeine total.	View
Herbal Sleep Teas	Limited evidence	A wind-down routine	Blends of valerian, chamomile, lemon balm and passionflower deliver far less than the studied doses. The ritual is the reliable part; chronic insomnia is better treated with CBT-I than with any tea.	View
Detox Tea Blends	Limited evidence	Nobody: avoid	Built on senna and other stimulant laxatives: the weight lost is water and stool, the detox premise has no scientific basis, and the category has documented harms and undeclared drug adulteration.

Our verdict

Drink hibiscus if you want a tea with a measurable effect (a small drop in blood pressure) and ginger for nausea. Chamomile, lemon balm and sleep blends are pleasant and low-risk, but their evidence is weak or comes from extracts. Peppermint helps IBS only as enteric-coated capsules. Keep mate and guayusa within your caffeine budget, never drink mate scalding hot, and skip detox teas entirely.