The guava has been cultivated and distributed by man, by birds, and sundry 4-footed animals for so long that its place of origin is uncertain, but it is believed to be an area extending from southern Mexico into or through Central America. It is common throughout all warm areas of tropical America and in the West Indies (since 1526), the Bahamas, Bermuda and southern Florida where it was reportedly introduced in 1847.
Make tea by boiling the leaves for stomach ache and dysentery. It is used for amoeba hystolitica. Apply a tea to itchy skin. The bark (tallo) has a thin skin, roast it and grind it into powder and then use it as a bandage for herida (wound). It works like tequesquite.
The fruit and the leaf lower blood pressure. Guayabo leaves are good for artery pressure, for a hangover, you boil one leaf and feel better, it stabilizes the artery pressure, with a leaf tea.
Though most people recognize Psidium guajava L. -more known as guava- for its culinary uses, this plant has also been used medicinally in many traditional systems of healing. The leaves are especially useful when treating bacterial infection and are commonly used for combating gastroenteritis when antibiotics are unavailable (Gonçalves et al. 2008). This traditional use has been supported in clinical trials where extracts of the P. guajava leaf were found to be highly effective at inhibiting Staphylococcus aureus (ibid.), a diarrhea-causing bacteria, and in one study reduced the bactericidal concentration of a multidrug resistant (MDR) strain of the bacteria by 80% (Anas et al. 2008). Other studies have demonstrated a synergistic effect between P. guajava and antibiotics, when used in combination: with P. guajava increasing the efficacy of the drugs, and thus improving treatment outcomes (Betoni et al. 2006; Morais-Braga et al. 2016). Furthermore, a tea made from the leaves of P. guajava exhibited potential for use as an antiviral in the treatment of influenza (Sriwilaijaroen et al. 2012); one which is less likely to lead to viral drug resistance than its synthetic counterparts (ibid.). In addition to combating infectious, viral, and parasitic illness in the gastrointestinal tract (GIT), P. guajava has demonstrated antidiarrheal activity akin to its over the counter, pharmaceutical counterparts, which slow GIT motility (Mazumdar et al. 2015).
Another traditional use of P. guajava, which has been supported in clinical trials, is its employment as an antidiabetic. Extracts of the plant have been shown to reduce blood glucose levels (ibid.) in hyperglycemia and may also be useful in preventing comorbidities which arise in diabetes, such as diabetic peripheral neuropathy (Wang)
Anas, K., Jayasree, P. R., Vijayakumar, T., & Kumar, P. R. (2008). In vitro antibacterial activity of Psidium guajava Linn. leaf extract on clinical isolates of multidrug resistant Staphylococcus aureus.
Betoni, J. E. C., Mantovani, R. P., Barbosa, L. N., Di Stasi, L. C., & Fernandes Junior, A. (2006). Synergism between plant extract and antimicrobial drugs used on Staphylococcus aureus diseases. Memórias Do Instituto Oswaldo Cruz, 101(4), 387–390. https://doi.org/10.1590/s0074-02762006000400007
Gonçalves, F. A., Andrade Neto, M., Bezerra, J. N. S., Macrae, A., Sousa, O. V. D., Fonteles-Filho, A. A., & Vieira, R. H. (2008). Antibacterial activity of GUAVA, Psidium guajava Linnaeus, leaf extracts on diarrhea-causing enteric bacteria isolated from Seabob shrimp, Xiphopenaeus kroyeri (Heller). Revista Do Instituto de Medicina Tropical de São Paulo, 50(1), 11–15. https://doi.org/10.1590/s0036-46652008000100003
Mazumdar, S., Akter, R., & Talukder, D. (2015). Antidiabetic and antidiarrhoeal effects on ethanolic extract of Psidium guajava (L.) Bat. leaves in Wister rats. Asian Pacific Journal of Tropical Biomedicine, 5(1), 10–14. https://doi.org/10.1016/s2221-1691(15)30163-5
Morais-Braga, M. F. B., Carneiro, J. N. P., Machado, A. J. T., dos Santos, A. T. L., Sales, D. L., Lima, L. F., Figueredo, F. G., & Coutinho, H. D. M. (2016). Psidium guajava L., from ethnobiology to scientific evaluation: Elucidating bioactivity against pathogenic microorganisms. Journal of Ethnopharmacology, 194, 1140–1152. https://doi.org/10.1016/j.jep.2016.11.017
Morton, J. 1987. Guava. p. 356–363. In Morton, Julia F. (ed.). Fruits of Warm Climates. Creative Resource Systems, Inc. Miami, Florida, USA. https://hort.purdue.edu/newcrop/morton/guava.html
Sriwilaijaroen, N., Fukumoto, S., Kumagai, K., Hiramatsu, H., Odagiri, T., Tashiro, M., & Suzuki, Y. (2012). Antiviral effects of Psidium guajava Linn. (guava) tea on the growth of clinical isolated H1N1 viruses: Its role in viral hemagglutination and neuraminidase inhibition. Antiviral Research, 94(2), 139–146. https://doi.org/10.1016/j.antiviral.2012.02.013