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Yerba Mate Info Summary
by Erowid
Aug 2004 1.0
Yerba Mate (tea) is made from the leaf of the plant Ilex paraguariensis. It contains caffeine, theophylline, theobromine, and related chemicals that are all stimulants.

Although Yerba Mate is widely used in South America, there unfortunately appears to be gathering evidence that chronic use of Mate increases the risk of several cancers, including bladder (De Stefani 1991), oral, esophageal (throat) (Pintos 1994), and lung (De Stefani 1996). There is also one case report of a woman who had liver problems after long-term use of Yerba Mate (McGee 1976). Because of the nature of correlative cancer studies, it is important to note that the exact cause of the cancer increases has not been identified and there is still the possibility that the Yerba Mate is not the direct cause of the increased cancer rates among users.

  • As with other caffeine-containing teas, Yerba Mate's caffeine and theobromine will interact with a wide variety of pharmaceuticals and can increase heart rate and blood pressure.

  • Caffeine is known to cause decreased blood levels of benzodiazepines such as diazepam (Valium) or alprazolam (Xanax).

  • Caffeine is known to cause diueresis (increased urination).
Adverse Reactions & Overdoses
  • Adverse reactions to Yerba Mate are likely to be the same as with other caffeine-containing teas, coffees, or drinks. At lower doses, unwanted symptoms can include restlessness, reduced patience, irritability, difficulty falling asleep, and other mild-stimulant reactions.

  • At higher doses, adverse reactions include nausea, vomiting, headaches, and unconsciousness. Very high doses of caffeine can be fatal, although it is nearly impossible to accidentally reach those levels using tea.
See the Caffeine Vault.

References #
  1. De Stefani E, Correa P, Fierro L, Fontham E, Chen V, Zavala D. Black tobacco, mate and bladder cancer. A case-control study from Uruguay. Cancer 1991;67:536-40. PubMed
  2. De Stefani E, Fierro L, Correa P, Fontham E, Ronco A, Larrinaga M, Balbi J, Mendilaharsu M. Mate drinking and risk of lung cancer in males: a case control study from Uruguay. Cancer Epidemiol Biomarkers Prev 1996;5:515-9. PubMed
  3. Goldenberg D. Mate: a risk factor for oral and oropharyngeal cancer. Oral Oncol 2002;38:646. PubMed
  4. McGee J, Patrick RS, Wood CB, Blumgart LH. A case of veno-occlusive disease of the liver in Britain associated with herbal tea consumption. J Clin Pathol 1976;29:788-94. PubMed
  5. Pintos J, Franco EL, Oliveira BV, Kowalski LP, Curado MP, Dewar R. Mate, coffee, and tea consumption and risk of cancers of the upper aerodigestive tract in southern Brazil. Epidemiology 1994;5:583-90.PubMed