It’s essential to be cautious with information that attributes to a single plant the power to cure complex conditions like the ones you mentioned. Guava leaves have beneficial properties, but they are not a cure for bone and joint diseases, gout, swollen legs, or fluid retention.

These conditions are serious and require specific diagnosis and treatment, which can only be prescribed by a healthcare professional. Relying solely on natural remedies can delay proper treatment and worsen the problem.

Known Properties of Guava Leaves
Guava leaves are rich in bioactive compounds, such as antioxidants and tannins, which give them some properties that may be useful for general health, but not as a treatment for the conditions you mentioned.

Anti-inflammatory and Analgesic Action: Some studies suggest that guava leaves have properties that can help reduce inflammation and pain. However, the effect is generally mild and does not replace medication for chronic conditions such as arthritis or gout.
Sugar and Cholesterol Control: Guava leaf infusion can help regulate blood sugar levels and reduce “bad” cholesterol (LDL), contributing to cardiovascular health and diabetes control.
Digestive Health: The leaves are best known in folk medicine for their effectiveness in treating diarrhea and relieving stomach pain, due to their astringent properties.
Why they are not suitable for your conditions
Their use for the conditions you mentioned is inappropriate because:

Gout: This is caused by excess uric acid in the blood. Treatment requires dietary control and, often, specific medication to reduce uric acid levels, something guava leaves cannot do. Bone and Joint Diseases: Conditions such as rheumatoid arthritis or osteoarthritis are inflammatory or degenerative diseases that require targeted medical treatments, such as physical therapy and medications, to control their progression.

Fluid Retention and Swollen Legs: Swelling can be a symptom of serious kidney, heart, or liver problems. The cause needs to be identified and treated by a doctor. Ignoring swelling can have dangerous consequences.
Guava leaves can be a beneficial addition to a healthy diet, but they should never be used as an alternative to professional medical treatment. For any health problem, the first and safest option is always to seek medical advice.