Boui-ogi-to (防已黄耆湯) is a time-honored Kampo herbal formula originating from the classical Chinese medical text Jinkui Yaolue (c. 200 CE), adapted and standardized in Japanese Kampo medicine. It is a multi-herb combination designed specifically for people described in Kampo as having a 'flabby' constitution — individuals who carry excess fluid, sweat easily, and feel tired despite being overweight. The formula is widely used in Japanese integrative medicine and is officially approved by Japan's Ministry of Health as a prescription Kampo medicine.

The formula works by supporting the body's natural ability to regulate fluid distribution — encouraging the elimination of excess water through the kidneys while strengthening what Kampo calls 'wei qi,' or the body's surface energy that governs sweating and fluid balance. Stephania root acts as the main diuretic and anti-inflammatory driver, while Astragalus helps tone the body's energy and reduce abnormal sweating. Atractylodes supports digestive function and fluid processing, and licorice harmonizes the whole formula while also calming inflammation.

In Japan, Boui-ogi-to is most commonly dispensed as standardized granules (Tsumura and Kotaro brands are the most clinically studied) that dissolve in warm water, closely mimicking the traditional decoction. Traditional preparation involves simmering the dried herbs together for 20–30 minutes. Granule and extract powder forms are convenient and maintain consistent dosing of the active constituents.

• Water retention and edema
• Overweight and obesity (fluid type)
• Knee joint pain and swelling
• Metabolic syndrome
• Excessive sweating
• Fatigue with poor muscle tone
• High blood pressure (mild)
• Knee osteoarthritis

• Progression of metabolic syndrome risk factors in overweight individuals (supported by clinical trial data showing improvements in multiple cardiovascular risk markers)

Boui-ogi-to is a multi-herb formula and is not found in food. However, you can support the same fluid-balancing and anti-inflammatory goals through diet. Foods that help: cucumber, celery, and asparagus are natural diuretics that reduce water retention; green tea provides anti-inflammatory catechins similar in spirit to the formula's action; oily fish (salmon, sardines) supply omega-3s that reduce joint inflammation; ginger and turmeric used in cooking echo the warming anti-inflammatory herbs in the formula. Reduce sodium intake, which directly worsens fluid retention, and minimize processed foods and alcohol, which stress the liver and kidneys that this formula is trying to support. Foods to limit: High-sodium processed foods (worsen fluid retention), Alcohol (increases fluid imbalance and stresses liver), Licorice-containing foods or candies (additive effect with the licorice in the formula — can raise blood pressure).

• Digestive discomfort or loose stools (mild, typically early in use)
• Raised blood pressure with prolonged use (due to glycyrrhizin in licorice)
• Low potassium (hypokalemia) with long-term use — can cause muscle weakness or cramps
• Mild nausea in sensitive individuals
• Rare allergic skin reactions

• Recommended daily: 7.5 g/day of standardized granules (Tsumura formulation), typically divided into 2–3 doses; traditional decoction dose is approximately 9–15 g of the dried herb combination per day
• Best time of day: Taken 30 minutes before meals, 2–3 times daily (traditional Kampo timing to maximize absorption before digestion begins)
• With or without food: Take on an empty stomach or 30 minutes before meals for best effect; if stomach sensitivity occurs, take with a small amount of warm water or light food
• Time to effect: Fluid retention may improve within 1–2 weeks; joint pain and weight changes typically take 4–8 weeks of consistent use
• How long to take it: Use for 8–12 weeks as an initial course; reassess with a healthcare provider before continuing long-term due to licorice content; cycling (e.g., 8 weeks on, 2–4 weeks off) is reasonable for ongoing management