Interactions & dangerous combinations

Natural remedies are effective. And that's precisely why they can interact with medications, other plants, or foods. "Herbal" doesn't mean "without effect." This isn't a cause for concern, but it's a good reason to be aware of the most important combinations. Here are the best-documented ones, explained in a friendly way.

St. John's wort and medications

St. John's wort is a wonderful plant for mild mood swings, but it's also the most potent herb with numerous interactions. Its components stimulate an enzyme in the liver that breaks down many medications more quickly. This makes them less effective, often without you noticing.

If you are taking any of these medications, please only use St. John's wort after a brief consultation with your doctor or pharmacist. This can be clarified in five minutes.

Ginkgo and blood thinners

Ginkgo has traditionally supported blood circulation. Research on whether it increases the tendency to bleed is inconsistent: Controlled studies with standardized extracts have mostly found no significantly increased risk, but there are individual case reports, and the package inserts of many anticoagulants explicitly mention ginkgo.

Therefore, the simple rule is: If you are taking aspirin, warfarin, modern anticoagulants, or SSRIs, briefly mention the combination beforehand. And before a planned surgery or dental procedure, it's best to mention the ginkgo yourself.

Licorice and blood pressure or heart medications

The glycyrrhizin in licorice blocks an enzyme that normally breaks down cortisol. In larger quantities, this causes your body to retain salt and water and lose potassium, leading to increased blood pressure. For healthy individuals, the occasional licorice twist is not a problem; the German Federal Institute for Risk Assessment (BfR) recommends no more than about 100 grams of strong licorice per day as a guideline.

You should be careful with blood pressure medication (its effect may decrease), diuretics (even more potassium loss) and especially with cardiac glycosides such as digoxin, because low potassium dangerously increases their effect.

Grapefruit and certain statins

Grapefruit is a classic example of an underestimated drug interaction: it inhibits an intestinal enzyme for days, regardless of when you eat it. As a result, some medications enter the bloodstream in much higher concentrations than intended.

Valerian and sedatives or alcohol

Valerian works by calming the brain through the same neurotransmitter as prescription tranquilizers. If you combine both, or valerian with alcohol, the sedative effect is compounded, and your reaction time may be more impaired than you think. It's best not to mix them before driving or operating machinery.

Vitamin K-rich herbs and Marcumar

Parsley, kale, and spinach are packed with vitamin K, the natural antagonist of anticoagulants like warfarin. The modern recommendation surprises many: don't avoid them, but eat them regularly. The problem isn't the green vegetables themselves, but the fluctuations in consumption. Large fluctuations cause unpredictable fluctuations in blood clotting levels.