Psidium Guajava (Guava Leaf): A Review on Its Phytochemistry and Medicinal Uses

Psidium guajava L. (guava) is a tropical plant widely recognized for its diverse therapeutic applications and rich phytochemical profile. The leaves of P. guajava, in particular, have been extensively used in traditional medicine across tropical and subtropical regions, including the Philippines, for the treatment of wounds, infections, diarrhea, fever, and diabetes. This narrative review aims to summarize and evaluate existing literature on the phytochemistry and medicinal uses of P. guajava leaves, with emphasis on the major bioactive compounds responsible for its pharmacological activities. Relevant studies were sourced primarily from Google Scholar using keywords such as "Psidium guajava," "guava leaf," "phytochemistry," and "medicinal uses," covering publications from 2000 to 2026. Findings reveal that guava leaves contain a diverse array of bioactive constituents — including quercetin, rutin, tannins, flavonoids, oleanolic acid, β-caryophyllene, and ellagic acid — that confer significant antimicrobial, anti-inflammatory, antioxidant, antidiarrheal, and antidiabetic effects. These properties are supported by both ethnomedicinal records and preclinical evidence derived from in vitro and animal-based studies. While the evidence strongly validates the traditional use of P. guajava leaves, clinical studies in human populations remain limited. This review underscores the therapeutic potential of P. guajava leaves and highlights the need for standardized research and clinical trials to facilitate their integration into evidence-based healthcare practices.