Educational information, not medical advice — ask your doctor or midwife.
Labrador tea is a low evergreen shrub from cold northern bogs. Its dried leaves are brewed as a herbal tea. In French Canada it is called thé des bois, and in English it is often called marsh tea.
The name covers more than one plant. Ledum latifolium is an old botanical name for Rhododendron groenlandicum. A look-alike relative, Ledum palustre, holds much more of the plant's toxic oil.
Folk and Eclectic healers in North America used the tea for coughs, colds, upset stomach and itchy skin. Human evidence for any of these uses is very thin. Long use in a tradition is not proof that a remedy works, and it is not proof that it is safe.
This page treats Labrador tea as a caution herb. It is drunk as a beverage in parts of Canada, but strong brews, large amounts and mistaken plant identity have caused real harm.
No one has shown in people how Labrador tea works, or that it works at all.
Most of what is known comes from lab dishes and animals. In cell studies, leaf extracts appear to lower markers of swelling. In test tubes they slow the growth of some bacteria and fungi.
In mice fed a high-fat diet, extracts appeared to improve how the body handled blood sugar. That work grew out of research on Cree traditional medicine in Canada. Whether the same thing happens in people is not known.
The leaf oil contains ledol. In animals, ledol acts on the brain. It can calm at low amounts and poison at higher ones.
That split is the main reason brew strength matters. A quick steep pulls out little oil. A long steep, a boiled-down brew, or a handful of leaves pulls out much more.
Dried leaf for tea is by far the most common form.
- Loose dried leaf, sold in bags by wild-herb suppliers.
- Tea bags, often blended with other northern herbs.
- Tinctures, which are alcohol extracts sold by some herb shops.
- Essential oil, sold for scent only. It must never be swallowed.
- Fresh leaves picked by foragers, which carry the highest risk of the wrong plant.
Labelling is often loose. Packages may say Ledum, marsh tea or muskeg tea without naming the exact species. Ask the seller which plant it is and where it was picked.
Indigenous peoples across northern North America used the leaves as a daily drink and as a medicine. Uses recorded by later writers included coughs, colds, stomach trouble and washes for itchy skin.
Settlers took up the drink too. One story ties it to colonial boycotts of imported tea, though the record is mixed.
Nineteenth-century Eclectic physicians in the United States listed Ledum for coughs and skin complaints. Their notes were based on case reports and custom, not on trials.
The dried leaf was also strewn among clothes to keep moths and fleas away. That use points at the strength of the oil.
Stop drinking it and call a doctor if you get nausea, cramps, a headache or a rash that does not settle.
Get urgent medical help for these signs:
- Confusion, odd thoughts or trouble staying awake.
- Trembling, twitching or a seizure.
- A slow, racing or irregular heartbeat.
- Fainting, or feeling you are about to faint.
- Repeated vomiting or severe stomach pain.
If a child drinks it, call a poison centre straight away, even if the child seems fine.
In the United States it is sold as a herbal tea or dietary supplement. The FDA does not review such products for how well they work before sale.
In Canada it is drunk as a traditional beverage, and some products carry a natural health product licence. In Europe, Ledum palustre appears mainly as a homeopathic ingredient rather than a tea.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
What it is typically used for, usual dose, cautions, and the study behind it where real trial data exists.
One email with the summary. We'll also send a short weekly evidence update — unsubscribe any time.
