DrG's Medisense Feature Article

Itch
By Ann Gerhardt, MD
August 2024
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Bottom Line at the Top:  Itch can be crazy-making. Whether caused by something simple or an underlying disease, it won’t resolve if the cause is not identified and eliminated or treated.

An unresolved itch can cause a huge amount of misery, far out of proportion to the cause, often just simple allergy, rash, dry skin or insect bite.

Homegrown Remedies abound:  Ice it, slap it and/or oatmeal bathe it, then repeat when itch recurs, which it surely will.  Band-Aid it, to keep from scratching, then wait for it to subside.

Itch is caused by inflammatory substances that are part of the body’s response to micro- or macro-injury.  If caused by allergy to substances (allergens) ingested or touched, it might respond to oral anti-histamines or topical antihistamine or steroid creams, but that’s only if the allergen exposure is terminated.

The brain perceives itch and pain using some of the same nerves, but not all skin pain nerves elicit the sensation of itch.  When a particular nerve is stimulated, the brain can tell the difference between pain and itch.  By acting on these pain/itch nerves, a lidocaine or menthol cream might stop itches caused by a bite, rash or the healing process.  I like Blue Emu or Icey Hot, though they aren’t perfect and don’t last long.

Common causes of itch are dry and old skin’s poor integrity that permits entrance of irritants and bacteria , any of which might induce inflammation and itching.  The treatment is to hydrate the skin by bathing, then sealing with moisturizing skin creams.

Some diffuse itches, if not related to dry, old skin, are caused by accumulation of abnormal body chemicals, like bilirubin in liver disease or urea in kidney disease.  In that case, only treatment that reduces bilirubin or urea concentration, or by reversing the disease that caused it, will alleviate the itch.
 
Itch might be the first sensation caused by skin cancer if it has an inflammatory component.  For persistent localized itch, take a picture of the area and see a dermatologist if itching persists, turns into pain or the area grows. 

If shortness of breath, wheezing or lightheadedness accompany itching, the trigger is throughout the body and won’t respond to a moisturizing cream or simple antihistamine or steroid.  See a doctor at an urgent or emergency care facility if the symptoms are severe and unremitting, since some immune disorders can be life-threatening.  Then, if the cause is not obvious, see a doctor specializing in allergy or immunology.  Some autoimmune disorders, like lupus, polymyositis or rheumatoid arthritis, may cause itch.  If you have diffuse itch and a family history of autoimmune disease, remind your primary doctor about it. 

In summary, if an itch becomes miserable, identify irritants and allergies and try simple remedies.  If they fail, see your doctor.