Kampo Shakuyaku-kanzo-to

Shakuyaku-kanzo-to works through two primary mechanisms. Paeoniflorin, from Paeonia root, acts as an antispasmodic by modulating calcium channels and reducing smooth muscle contraction. Glycyrrhizin and glycyrrhetinic acid from Glycyrrhiza (licorice) provide anti-inflammatory effects and enhance the bioavailability of paeoniflorin. The combination creates a synergistic effect that relaxes skeletal and smooth muscle spasms. Evidence Level: C (preclinical and limited clinical data).

Shakuyaku-kanzo-to has significant drug interactions due to its licorice component. Glycyrrhizin can potentiate the effects of corticosteroids and diuretics, increasing risk of hypokalemia. It should not be combined with digoxin, as low potassium levels increase cardiac toxicity. Concurrent use with antihypertensive medications may reduce their efficacy. Avoid combining with other potassium-depleting agents. Patients on warfarin should monitor INR levels closely. Evidence Level: C.

The standard adult dosage for Shakuyaku-kanzo-to is typically 2.5 grams of powdered extract taken three times daily, usually before or between meals. This follows traditional Kampo dosing conventions. Dosage may vary based on the specific manufacturer and formulation, such as extract granules versus raw herb decoctions. Always follow manufacturer instructions or consult a qualified Kampo practitioner for individualized dosing. Evidence Level: Traditional/C.

Shakuyaku-kanzo-to is contraindicated during pregnancy. The Glycyrrhiza (licorice) component contains glycyrrhetinic acid, which can cause pseudoaldosteronism, leading to fluid retention, elevated blood pressure, and dangerous electrolyte imbalances. These effects pose significant risks to both maternal health and fetal development. Additionally, some constituents may exert hormonal effects. Pregnant women should avoid this formula entirely and consult their healthcare provider for safer alternatives. Evidence Level: C/Theoretical.

Shakuyaku-kanzo-to is primarily used for treating muscle cramps and spasms, particularly leg cramps. It is also used in polycystic ovary syndrome (PCOS) management due to its antispasmodic and hormone-modulating properties. Other traditional applications include abdominal pain relief, dysmenorrhea, and general smooth muscle relaxation. The formula is considered a primary antispasmodic agent in Japanese Kampo medicine. Evidence Level: C (limited clinical trials support these uses).