There is a lot of research on why nettle extracts causes skin irritation and a stinging sensation. However, I cannot find information on how the extract is injected in human skin. Similarly, I haven't been able to find information on how the pressure is built up in the trichome, nor how the silica tip is inserted in the skin.

Suggestions for articles or books on this topic are welcomed.

  • $\begingroup$ Does this answer your question, or is it too unspecific: Wikipedia: Stinging plant? $\endgroup$ May 19, 2015 at 8:30
  • $\begingroup$ sorry..but it's too unspecific....but thnx...neways... $\endgroup$ May 20, 2015 at 16:49
  • $\begingroup$ There found formic acid, some neurotransmitters which include Acetylcholine. $\endgroup$
    – user25568
    Sep 1, 2016 at 19:17

1 Answer 1


The stinging hairs (trichomes) of the common North American nettle (Urtica dioica) are sharp, pointed cells. These nucleated cells are embedded in a base of smaller epidermal cells. The shaft of the trichome is composed of silica. Upon touch, the tip breaks off, leaving a sharp tip similar to a hypodermic needle. The hollow trichome penetrates the skin, and toxin from the base is injected into the skin tissue. The stinging toxin includes a mixture of histamine, acetylcholine and 5-hydroxytryptamine (Online Textbook of Natural History).

trichome trichomes
Left: schematic of a stinging cell, or trichome of a nettle. Right: trichomes on the stem of Hesperocnide tenella. Source: Online Textbook of Natural History

I couldn't find any info on trichome pressure. It may be that the toxins are released passively. Otherwise, high concentrations of dissolved matter may attract water in the base, increasing the pressure (much like turgor present in many plant cells).

  • $\begingroup$ thanx...but this I'm afraid is really a general statement....are there any scientifc studies or experiment demonstrating this??...upvoting the ans...because of the pic & for your effort...but the answer is ...I am sorry to say...incomplete... $\endgroup$ May 20, 2015 at 16:54
  • $\begingroup$ @souvikbhattacharya - The information comes from an online Textbook, but I haven't found specific primary research on it. My answer is the best I could do. $\endgroup$
    – AliceD
    May 21, 2015 at 0:18
  • $\begingroup$ no no....I understand....there really is no study from this mechanistic angle....I was just double checking...neway you provided a crucial detail....so thanks again for that... $\endgroup$ May 29, 2015 at 8:52

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