March 1, 2025

The Baptistery of St. John (Battistero di San Giovanni), Continued

When discussing Saint John the Baptist, one plant that medical practitioners should not overlook is Saint John’s Wort (Hypericum perforatum).

This medicinal herb, known as "the herb of St. John," has deep historical and symbolic significance.

The botanical name, Hypericum perforatum, originates from ancient Greece, where this flower was placed on “statues to ward off evil.”

Its Latin-derived name, Hypericum, combines “hyper” (above) and “icon” (statue), reflecting its protective usage in rituals against misfortune.

For centuries, it has been cherished as a “plant that wards off evil.”

Although native to Europe, Saint John’s Wort later spread to regions such as the Americas and is now found in the wild in some parts of Japan.

The herb blooms with yellow flowers around St. John’s Day , also known as the Nativity of St. John (June 24), traditionally harvested on this date, which is how it came to bear his name.

In Japan’s Hokkaido region, the flowers bloom adorably around mid-July.

The plant’s folklore is intriguing: when its petals are crushed, they release a red liquid.

This has led to the legend that the herb sprouted from the blood of John the Baptist.

Historical Uses and Modern Applications

Since ancient Greece, Saint John’s Wort has been referred to as the “herb that drives away devils.”

It was not only used in rituals but also applied externally for treating wounds and burns and ingested as a treatment for depression.

Indigenous peoples of the Americas utilized it for various purposes, including as an abortifacient, anti-inflammatory agent, and disinfectant.

It has also been used to produce red and yellow dyes.

In Japan, supplements (in tablet or capsule form) and herbal teas containing Saint John’s Wort are now available in pharmacies and online.

Precautions and Drug Interactions

However, consuming the compounds in this herb, such as hypericin and hyperforin, can induce certain enzymes that metabolize drugs in the body.

This may accelerate drug metabolism, in other words, breakdown, reducing the blood concentration and effectiveness of medications.

Abruptly discontinuing the herb can eliminate its enzyme-inducing effect, potentially causing a dangerous increase in drug blood concentrations and leading to adverse side effects.

Drugs Affected by Saint John’s Wort

Individuals taking the following medications should avoid consuming Saint John’s Wort:

Iron supplements

Omeprazole (acid secretion inhibitor)

Rivaroxaban, Warfarin (anticoagulants)

Fluvoxamine, Paroxetine, Sertraline (antidepressants)

Digoxin, Digitoxin, Methyldigoxin (cardiac stimulants)

Amiodarone, Quinidine, Disopyramide, Propafenone (antiarrhythmic agents)

Theophylline, Aminophylline (bronchodilators)

Phenytoin, Carbamazepine, Phenobarbital (antiepileptic drugs)

Estradiol (estrogen)

Voriconazole (antifungal drug)

Cyclosporine, Tacrolimus, Everolimus (immunosuppressants)

Gefitinib, Imatinib (anti-cancer drugs)

Indinavir (HIV medication)