Science Questions

Why do my surgical scars itch more with exercise? The two may not be related, but the more I exercise, the more my scars itch. Laura in Maryland, USA

When you have surgery, the surgeon has to cut through the skin. In the process of cutting through the skin, they will almost certainly cut through some nerves. Scientists have now come round to thinking that itching is caused by a special class of nerve fibre that seems to convey the sensation of itchiness. The reason that scars and scabs itch so much is perhaps that when these tiny nerves try to re-grow, it's possible that they sometimes fire off inappropriately and fool the brain into thinking that there's an itch there when in reality there isn't. Another possibility is that when the tissue is putting itself back together when you have a scar, then you get lots of tension and funny pulling within the skin. It's possible that this may be triggering off the itch sensitive nerves as well.

October 2005