• Question: why do scabs itch when they've dried?

    Asked by bola123 to Lyn, Katy, Paul, PB, Ruth on 20 Jun 2013.
    • Photo: Peter Balfe

      Peter Balfe answered on 20 Jun 2013:

      The itch is a signal to scratch the scab, if the wound has healed the scab will fall off, leaving the new skin. If not the scratching stimulates the Mast cells in the skin to release histamines, reddening the skin as the blood vessels dilate. This increased blood supply drives the skin cells to grow and fill in the wound some more.
      But scratching so hard as to break the scab can cause fresh wounding and even lead to scarring, so the old adage of “don’t keep scratching it” has some real wisdom.

    • Photo: Katy Brown

      Katy Brown answered on 20 Jun 2013:

      Peter has it I think. The skin around the scab might also itch because it is being pulled and moved around while the wound heals.

    • Photo: Paul Waines

      Paul Waines answered on 25 Jun 2013:

      They do this because they are start to peel off as the cut heals- this stimulates the nerves and produces itching

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