Psidium guajava L., commonly known as guava, is a shrub that belongs to the Myrtaceae family and is native to Southern Mexico, Central America, and South America. The plant is widely cultivated in almost all parts of the world because it grows easily in tropical and subtropical climates. In several countries, guava leaves are traditionally used for, especially, anti-diarrhea. In another dosage form, i.e., infusion or decoction, the leaves prove effective in the treatment of rheumatism, diarrhea, diabetes mellitus, and cough in India, China, Pakistan, and Bangladesh. In South Asia and Nigeria, a guava leaf decoction is used for mouthwash and anti-bacterial agent. Some external uses of the plant include topical application on injured skin, as widely practiced in Mexico, Brazil, the Philippines, and Nigeria. Also, in Ethnomedicine, the leaves are used by the people of the Muna tribe in Southeast Sulawesi as anti-diarrhea medicines. 1,2 Guava leaves have active compounds, such as polyphenols, ascorbate, gallic acid, caffeine, flavonoids (quercetin), tannins, and isoprenoids. These are associated with several pharmacological activities, namely cough suppressant, anti-spasmolytic, anti-bacterial, anti-amoebic, antifungal, anti-diarrhea, anti-hyperglycemia, antioxidants, cardioprotective effects, and immunostimulants. 3,4