Educational information, not medical advice — ask your doctor or midwife.
Nasturtium is a garden plant with round leaves and bright orange, red or yellow flowers. The leaves, flowers and young seed pods are edible. They taste sharp and peppery, like watercress.
Its botanical name is Tropaeolum majus. In French it is called capucine. It came to Europe from South America in the 1500s and spread fast as a garden and kitchen plant.
European folk use pointed it at coughs, colds and bladder complaints. It was also eaten as a salad green. Traditional use is not proof that a plant works, and it is not proof that it is safe.
Here is the honest verdict on the evidence. Most human studies tested nasturtium mixed with horseradish root, not nasturtium on its own. Those studies suggest a possible role in minor airway and bladder infections, but they are few, mostly from one country, and often industry linked.
The short answer: the proposed mechanism comes mainly from lab work, not from people.
The leaves hold glucosinolates, often called mustard oil compounds. When you chew or crush a leaf, a plant enzyme turns them into benzyl isothiocyanate. That is the hot, peppery part.
In test tubes, benzyl isothiocyanate slows the growth of several bacteria and some yeasts. In cell studies it also damps down some signals tied to swelling. Whether either happens in your body at food amounts is not established.
Some of the compound is taken up by the gut and leaves the body in urine. That is one reason folk use aimed it at the bladder. It is a plausible idea, not a proven one.
The same mustard oils explain the main downside. They irritate tissue. That is why strong products can burn the mouth, upset the stomach or redden the skin.
Most people meet nasturtium as food. Fresh leaves and flowers go into salads and garnishes. Unripe seed pods are sometimes pickled and used like capers.
Supplement forms include dried herb tablets and capsules. In Germany these are usually a fixed mix of nasturtium herb with horseradish root. Tinctures (alcohol extracts) and loose dried herb for tea are also sold.
Skin products are less common. You may find infused oils, creams or a simple wash made from the leaf.
There is no agreed standard strength across brands. Mustard oil content varies widely. Labels that name the plant part and the amount per dose are the more useful ones.
European folk healers treated nasturtium as a warming, cleansing herb. Writers from the 1600s onward noted its peppery taste and compared it to watercress and mustard.
It was eaten as a salad green and valued as a winter source of freshness. Country use included teas and syrups for coughs and colds. Crushed leaves were laid on scrapes and boils.
German folk practice linked it to the bladder and the airways. That line of use later shaped the modern tablets that pair it with horseradish root.
None of this history tells you whether it helps, and none of it tells you a safe amount.
Stop taking it and see a doctor if you get bad stomach pain, blood in your urine, or pain in your side or lower back.
Seek care the same day for a fever with a urine infection, for a cough lasting more than three weeks, or for any trouble breathing.
Get emergency help for swelling of the lips, face or throat, or a sudden rash with breathlessness.
In the UK, the EU, the US, Canada and Australia, nasturtium is an ordinary edible plant and is sold as food and as a food supplement. In Germany, fixed combinations of nasturtium herb and horseradish root are licensed as medicines. No country licenses nasturtium alone as a treatment for infection.
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.
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