# Yerba mate (Ilex paraguariensis) *Maté, Paraguay tea, Paraguay herb, Jesuit’s tea, Brazil tea, French *houx maté*; *Ilex paraguariensis* A. St.-Hil.; in pharmacy *Mate folium** **Known today as.** *Ilex paraguariensis*, an evergreen of the family Aquifoliaceae native to Paraguay, Uruguay, and parts of Brazil and Argentina. Grieve describes a large white-flowered shrub growing wild near streams and widely cultivated, with alternate, large, broadly toothed leaves and a red fruit the size of pepper grains. The leaves, dried by heat and powdered, make the drink; LiverTox finds caffeine in it at about the strength of tea or coffee, with theobromine, theophylline, and polyphenols. Kind: Plant > **Caution.** Not for people with stomach or duodenal ulcers, high blood pressure, irregular heartbeat or other heart disorders, an overactive thyroid, or conditions needing restricted fluids; not under eighteen, nor in pregnancy or breast-feeding, nor at bedtime. People taking MAO inhibitors should use it with caution, and its caffeine increases the side effects of sympathomimetic drugs. The 2025 meta-analysis recorded mucosal irritation, insomnia, rapid heartbeat, angina, headache, and stomach upset among adverse events. LiverTox rates it a possible but rare cause of clinically apparent liver injury. ## What was it used for? A stimulating, sustaining drink. Grieve writes that its name *yerba* “signifies the herb par excellence,” that the consumption in South America is vast, “drunk at every meal and hour,” and that the tea is so sustaining it is sometimes the only refreshment carried on a journey of several days. She gives it as tonic, diuretic, diaphoretic, and “powerfully stimulant,” causing purging and vomiting in large doses. ## What does modern science say? The European Medicines Agency’s herbal committee accepts the leaf as a traditional herbal medicine, “exclusively based upon long-standing use,” for symptoms of fatigue and weakness and to increase the amount of urine to flush the urinary tract in minor urinary complaints (monograph of 2010). A 2025 meta-analysis of thirteen randomised trials found that in pre-diabetes it may lower post-meal glucose, HbA1c, and insulin resistance, on two trials each, but found no significant effect on blood fats, fasting glucose, waist, or body mass. LiverTox, revised in 2024, notes that the general health claims for it have not been shown in rigorous, adequately powered trials. ## Pharmacognosy and toxicology - **caffeine**: at about the strength of tea or coffee - **theobromine**: - **theophylline**: - **polyphenols**: **Mechanism.** Not established in the sources read for this entry. **Standing.** European Union herbal monograph (2010): traditional use, “exclusively based upon long-standing use,” for fatigue and weakness and to flush the urinary tract in minor urinary complaints. ## What lore surrounds it? LiverTox records that the drink was first used by the native Guarani people and later popularised by the missionary Jesuits. Grieve adds that two of its North American relatives, *Ilex vomitoria* and *I. dahoon*, the cassena and dahoon holly, are emetic, and that a decoction was used by the Indians of North Carolina as yaupon, the ceremonial black drink. ## What did the older authorities say? **Grieve, *A Modern Herbal* (1931).** ‘Maté’ comes from the name of the vessel in which it is infused, with burnt sugar or lemon juice added; it is sucked through a tube, usually of silver, with a bulb strainer at the end, and the cup is passed round. Large sums were paid to the government for leave to gather the leaves, and Paraguay exported five to six million pounds a year. ## Sources - Grieve, M. *A Modern Herbal*, “Paraguay Tea.” As published on botanical.com. - European Medicines Agency, Committee on Herbal Medicinal Products. *European Union herbal monograph on Mate folium (Maté Leaf)*. EMA/HMPC/580539/2008, 6 May 2010. - European Medicines Agency, Committee on Herbal Medicinal Products. *Assessment report on Mate folium*. EMA/HMPC/580545/2008, 6 May 2010. - Li D, et al. (2025). Yerba Maté and its impact on glycemic control and metabolic health: a systematic review and meta-analysis. *Frontiers in endocrinology*. PMID 41244043. - LiverTox: Clinical and Research Information on Drug-Induced Liver Injury, “YerbaMate.” National Institute of Diabetes and Digestive and Kidney Diseases, updated 2024. NCBI Bookshelf. - European Medicines Agency, Committee on Herbal Medicinal Products. *European Union herbal monograph on Mate folium (Maté Leaf)*. EMA/HMPC/580539/2008, 6 May 2010. - European Medicines Agency, Committee on Herbal Medicinal Products. *Assessment report on Mate folium*. EMA/HMPC/580545/2008, 6 May 2010. - Li D, et al. (2025). Yerba Maté and its impact on glycemic control and metabolic health: a systematic review and meta-analysis. *Frontiers in endocrinology*. PMID 41244043. - LiverTox: Clinical and Research Information on Drug-Induced Liver Injury, “YerbaMate.” National Institute of Diabetes and Digestive and Kidney Diseases, updated 2024. NCBI Bookshelf. --- *Yerba mate.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-10-17. The Thinking Press. https://thethinkingpress.org/materia-medica/yerba-mate Historical description, not medical advice.