Kigen-to is a five-herb Japanese Kampo formula equivalent to the classical Chinese formula Gui Zhi Tang, one of the oldest and most foundational prescriptions in East Asian medicine. It combines cinnamon twig, white peony root, licorice root, ginger, and jujube date into a balanced formula designed to gently open the body's defenses and restore equilibrium. It has been standardized in Japan and is available as a pharmaceutical-grade granule preparation prescribed by licensed physicians.

The formula works by supporting the body's natural immune and circulatory response at the surface level — helping ease muscle tension, mild fever, and sweating associated with early illness. Cinnamon twig warms circulation and promotes a gentle sweat to clear pathogens; white peony root softens and relaxes muscles and blood vessels; licorice and jujube harmonize the formula and support energy; and ginger warms the digestive system to aid absorption and reduce nausea.

In Japan, Kigen-to is most commonly dispensed as TJ-45 granules (Tsumura brand), a standardized pharmaceutical preparation. Traditional practitioners may also prepare it as a raw herb decoction boiled in water. Granules are dissolved in hot water and consumed as a tea-like drink, which is the most clinically studied and standardized form.

• Common cold (early stage)
• Flu symptoms and mild fever
• Muscle aches and stiffness
• Sweating with chills
• Weak or sensitive immune system
• Nausea and digestive discomfort with illness
• Post-illness fatigue and recovery
• Mild autonomic nervous system imbalance

• Progression of early cold to more severe illness when taken promptly at symptom onset
• Recurrent cold and flu episodes in constitutionally weak individuals (with ongoing preventive use)

• Ginger tea
• Cinnamon (in warm drinks or porridge)
• Jujube dates (red dates / hong zao)
• Chicken or bone broth
• Garlic

• Mild nausea or stomach upset (usually early, resolves with food)
• Skin rash or itching (rare; discontinue if occurs)
• Fluid retention or ankle swelling (with prolonged use — due to licorice component)
• High blood pressure with long-term use in sensitive individuals
• Low potassium levels with extended use (especially if combined with diuretics)

• Recommended daily: Standard Tsumura TJ-45 granule dose: 7.5 g/day divided into 2–3 doses (as used in Japanese clinical practice). Traditional decoction: one packet of raw herbs (typically ~15–20 g combined) simmered in water, taken in 2–3 servings per day.
• Best time of day: Traditionally taken before meals (about 30 minutes before eating) to maximize absorption; for acute illness, doses are spread morning, afternoon, and evening.
• With or without food: Best taken on an empty stomach or 30 minutes before meals; if stomach sensitivity occurs, taking with a small amount of warm food is acceptable.
• Time to effect: Acute cold/flu: 1–3 days; chronic or constitutional use: 2–4 weeks.
• How long to take it: For acute illness (cold/flu): short courses of 3–7 days. For constitutional support or recurrent illness prevention: may be used for 4–12 weeks with practitioner guidance. Avoid unmonitored long-term use beyond 3 months due to licorice content.