A Medicine's Benefit and Its Side Effect Come From the Same Place

I often hear it said that "herbal medicine is mild, so it's fine to take for a long time." I do not simply believe this.

For a medicine to act on the body means it presses some switch of the body. And the very switch that produces the effect is often the very switch that, pushed too far, produces the side effect. Benefit and side effect do not come from two separate places; for the most part they come from a single place. I make sure to tell my patients this.

Take licorice as an example

Let us look at licorice, considered the most common and the mildest. One component of licorice is converted, by way of the gut bacteria inside the body, into an active substance, and this substance inhibits, in the kidney, an enzyme that switches off a stress hormone. As a result the body holds onto sodium and sends out potassium, and this becomes part of the beneficial action of soothing mucous membranes and calming inflammation.

But when that same action goes too far, the body holds onto water and sodium excessively so blood pressure rises, and as potassium is depleted, one can become weak and develop arrhythmia. The very mechanism that had been producing the effect, once it crosses the line, becomes the side effect itself. So with people who have weak hearts, kidneys, or high blood pressure, or who take diuretics, I am especially careful with prescriptions containing licorice.

Up to this point it is established pharmacology. This action of licorice and the electrolyte problems it causes are well documented, and I too have, during practice, reconfirmed this point and corrected my own thinking.

Instead of saying "you may take it for a long time with peace of mind," I choose to say "this medicine presses this kind of place, and so it has this kind of boundary." This is not to think less of the medicine, but to see it precisely.

I look at which switch the effect comes from

When I choose a medicine, I do not look at the effect alone; I look together at which switch that effect comes from, and whether that switch is dangerous for this patient. For the same symptom, if the conditions of the body differ, I use a different medicine. And I hold to the principle of using only as much as needed, only for as long as needed, and then withdrawing.

When you should go to a hospital first — do not compound your own medicine

This piece is not one that recommends or discourages any particular herb. I do not recommend obtaining herbs and decocting them on your own. In particular, those taking blood pressure medication, diuretics, or heart medication, and those with weak kidney or liver function, must consult a professional. If, while taking medicine, you suddenly swell, become weak, or your chest pounds, stop taking it and seek care.

There is no such thing as a mild herb

There is no such thing as a medicine that is mild in itself. Used precisely, it is mild; used carelessly, it becomes strong. So I tell you the boundary along with the benefit. Only when one can speak of the effect and the boundary together does one truly know that medicine.

References

• Gut bacteria convert the licorice compound, and the converted form blocks an enzyme in the kidney — which is why swelling, raised blood pressure and low potassium follow, and why the risk rises when a diuretic is taken alongside — Frontiers in Nutrition, 2021
• The same licorice compounds also calm inflammation in the gut lining and help it repair — International Journal of Molecular Sciences, 2022

Written by Dr. Heo Ji-young (PhD in Korean Medicine Pathology, Kyung Hee University · former Research Professor of Herbology, Kyung Hee University)