While studies, as of 2015, have not confirmed the medicinal effectiveness of guava, it is considered an herbal medicine, according to WebMD. People use guava to treat conditions such as colic, diarrhea, diabetes, heart disease and cancer.
Individuals use guava juice to help treat cuts and as a tea to relieve headaches, states MedlinePlus. The crushed leaves of the plant are reportedly effective for reviving a person who has fainted.
Guava is safe as a food and high in antioxidants, notes WebMD. As of 2015, studies have not determined appropriate dosages for guava as a medicine or established information concerning side effects.