Nasturtium Drug Interactions, Uses, Effectiveness, Safety & More

Nasturtium (Tropaeolum majus) is a flowering plant native to South America that is now grown in gardens around the world. It is popular as an ornamental plant, and its colorful flowers and peppery-tasting leaves are also used in cooking and salads.

Beyond food, nasturtium has a long history in traditional and folk medicine. People have used its leaves, flowers, and seeds for urinary and respiratory complaints and as a natural antimicrobial. In some countries, nasturtium is combined with horseradish in herbal products marketed for infections of the urinary and respiratory tracts.

Nasturtium is rich in compounds called glucosinolates, which break down into substances known as isothiocyanates (including benzyl isothiocyanate). These are the same family of compounds that give the plant its sharp, peppery taste.

In laboratory studies, these isothiocyanates appear to have antimicrobial activity against some bacteria and fungi. The plant also contains vitamin C and antioxidant compounds. It is important to know that most of this research is based on lab or animal studies, so it does not necessarily mean the same effects happen in the human body.

When eaten in normal food amounts, nasturtium leaves and flowers are generally considered safe for most people. The safety of concentrated extracts, capsules, and long-term medicinal use is less well studied.

People with stomach or intestinal ulcers or kidney problems should be cautious, since the plant's pungent compounds may irritate these areas. Children and people with sensitive stomachs should also use caution.

For pregnancy, there is not enough reliable safety information, so medicinal amounts should be avoided. For breastfeeding, safety is also unclear, so it is best to be cautious or avoid concentrated products. Always check with your pharmacist or doctor before starting nasturtium, especially if you take other medicines or have a health condition.

Nasturtium is usually well tolerated as a food. When taken in larger or concentrated amounts, possible side effects include stomach upset, heartburn, or irritation of the digestive tract because of its spicy isothiocyanate compounds.

Some people may have an allergic reaction or skin irritation, especially when it is applied to the skin. Stop using it and seek medical care if you notice swelling, trouble breathing, or a severe rash.

There is no well-established standardized dose for nasturtium. Amounts vary widely depending on whether you use fresh leaves, dried herb, tea, capsules, or a combination product.

The best approach is to follow the directions on the product label and not exceed the recommended amount. Because product strengths differ and reliable dosing research is lacking, check with your pharmacist or doctor before using nasturtium as a supplement.