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I have heard this on multiple occasions at the dentist and a quick search lists dentist after dentist telling patients to do this.

For example: These facial surgeons recommend:

If bleeding continues, bite on a moistened tea bag for thirty minutes. The tannic acid in the tea bag helps to form a clot by contracting bleeding vessels.

Livestrong does not tell readers to use a tea bag at the site of extraction, but offers the advice that:

Unique compounds found in green tea known as catechins are responsible for combating inflammation.

Is there evidence that either of these claims are medically true for the compounds indicated (or others found in tea)?

Please note: by "tea" I mean leaves from the Camellia Sinensis plant. Although "tea" also comes in the forms of herbal infusions containing mint and chamomile (for example), I would not expect these to contain the same compounds. If your research suggests otherwise, please include that information.

  • +1 Nice job reconciling the disparate processes of platelet aggregation and that of the the immune inflammatory response, while still defining for what constitutes "tea". Granted this question may be quite difficult to answer correctly, I think it is extraordinarily well-formed. – Monkey Tuesday Jul 14 '11 at 5:53
  • There is some research about tannic acid and clotting (here), but do tea bags supply a sufficient amount? – thisfeller Oct 12 '12 at 19:54
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I think we have to be skeptical of this claim that a tea bag offers additional help in stopping bleeding after dental extractions through chemical action vs just compression with a gauze cloth. First off there are no published studies of the efficacy of using tea bags. The claim is made often on various medical [0] and dental sites seemingly based on this paper [1]

Tannins have also been reported to exert other physiological effects, such as to accelerate blood clotting

But it's clear that as a review they are reporting other people's even earlier work. (The full text of the journal is available for US$46.) But what they could not have known in 1998 is that there are other substances found in tea that prevent clot formation.

The Daily Mail [2] reports

They believe that rutin - also present in black and green tea - could be used in future treatments to protect against heart attacks and strokes. Harvard researchers found that the chemical helped block a potentially dangerous enzyme involved in the formation of blood clots.

And from the actual paper (rutin = quercetin-3-rutinoside ) [3]

Cellular assays showed that quercetin-3-rutinoside inhibited aggregation of human and mouse platelets and endothelial cell-mediated fibrin generation in human endothelial cells. Using intravital microscopy in mice, we demonstrated that quercetin-3-rutinoside blocks thrombus formation in vivo by inhibiting PDI. Infusion of recombinant PDI reversed the antithrombotic effect of quercetin-3-rutinoside.

Protein disulfide isomerase (PDI) is an oxidoreductase that has recently been shown to participate in thrombus formation, and is released by platelets and endothelial cells.

[0] http://www.webmd.com/oral-health/guide/wisdom-teeth?page=2

[1] Chung KT, Wong TY, Wei CI, Huang YW, Lin Y. Tannins and human health: a review. Crit Rev Food Sci Nutr 1998 Aug;38(6):421-64. doi: 10.1080/10408699891274273. PubMed PMID: 9759559.

[2] http://www.dailymail.co.uk/health/article-2141602/Chemical-apples-onions-green-tea-help-beat-blood-clots.html

[3] Jasuja R, Passam FH, Kennedy DR, Kim SH, van Hessem L, Lin L, Bowley SR, Joshi SS, Dilks JR, Furie B, Furie BC, Flaumenhaft R. Protein disulfide isomerase inhibitors constitute a new class of antithrombotic agents. J. Clin. Invest. 2012 Jun;122(6):2104-13. doi: 10.1172/JCI61228. PubMed PMID: 22565308.

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Tea contains tannic acid, which is a mild astringent, which means it tends to contract skin and blood vessels. Just to confuse matters, "astringent" also refers to a certain tartness of taste, which is also a known quality of tea. Tea is only a mild astringent, but it's also a relatively harmless one, which makes it safe to put in the mouth without worrying about swallow some of the astringent material and having to worry about the blood vessels of the throat contracting, as might happen with a stronger astringent such as alum.

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