Itching, Scratching and Eczema

Itch signals are similar to pain signals and occupy the same nerve fibers.  Substances like histamine (the amine that causes widening of blood vessels) are set free and irritate nerve fibers in the skin.   Why does scratching feel so good?  Scratching occupies the nerve fibers and blocks the itch messages being sent to the central nervous system.  Healthy, normal scratching can remove the stimulus causing the itching (like a hair) and can sometimes trigger an immune response to remove the cause of the irritation.  That's the good news about scratching.

However, with eczema, scratching and rubbing causes thick skin.  Abnormally thick skin sends more messages of itch and fuels the Itch/Scratch Cycle.    Scratching also causes injury to the skin and direct release of inflammatory mediators that enhance or cause itching themselves. The more people with eczema scratch, the further they cause the inflammation that triggers the itch. 

See, also, the Watery, Itchy Blisters web page.

From Science Daily on Scratching: "Don't Scratch That Itch: Blocking The Protein IL-21R Helps Prevent A Form Of Eczema"

Antihistamines:  Are They Helpful?

I worked my way up to 20 antihistamines daily; but, even with that dosage, I was still tormented with severe itching.

From:  The University of Nottingham

The mechanism of itch in atopic eczema is still unknown. Some of the pruritus in atopic eczema may be induced by non-histamine mechanisms such as neuroactive peptides or central mechanisms.  Histamine is the most thoroughly studied pruritogenic mediator and was for long assumed to be the unique itch stimulus. Today, a number of other peripheral inflammatory mediators are known to act as pruritogenics, either by acting directly on peripheral nerve endings, or indirectly by releasing endogenous substances that in turn stimulate the nerve endings, for example serotonin, proteases (e.g. kallikrein, papain), peptides (e.g. bradykinin, sekretin) and prostaglandins (e.g. PGE1, PGE2 and PGH2) (Wahlgren, 1991). Histamine is the main itch-provoking substance in urticaria, but the role of histamine in other itching disorders including atopic eczema remains to be defined.   It is not understood, why for example erythema, sweating, dry skin or wool elicits itch in patients with AE and to what degree factors other than histamine play a role. Further, it is unclear whether potential beneficial effects of sedating antihistamines are due to their central effects (sedation) alone or due to their peripheral effects. In many tests and management guideline articles (McHenry et al., 1995), it is claimed that sedative antihistamines are more effective than low-sedating antihistamines. This appears to be based on scanty data (Krause & Shuster, 1983). Another issue relating to the use of antihistamines in atopic eczema is that they can only be used for short periods because tolerance to the effects is thought to develop quite quickly (Kemp, 1989). Another area of concern is that antihistamines have been linked with behavior disorders such as hyperactivity in children (Calmels et al., 1982).  So it is not clear

     i) if antihistamines are helpful in AE
     ii) whether only sedating ones are helpful
     iii) how long they are helpful for and
     iv) whether they demonstrate undesirable side effects

From Merk ... "Antihistamines are ineffective in suppressing allergic contact dermatitis."
 

Techniques To Help Curb Itching

Mineral Oil is Inert.  Read the Cortisone Web Page for important information.

Course Washcloth.  Sometimes you feel itchy because of the uneven skin feeling like little hairs that you need to scratch off.  I find that just gently rubbing the skin with a course washcloth smoothes the skin and helps alleviate that externally stimulated itch.

Ice  Therapy.  Dry eczema should not get wet to preserve the natural oils.  Try filling a plastic bottle (such as an empty vitamin bottle) with water and freeze it.  It can help block the itch signals and reduce the inflammation.  From Ice Therapy,  "Ice  decreases all of these:  swelling, tissue damage, blood clot formation, inflammation, muscle spasms, and pain."

Heat therapy:  Something I noticed that works is heat.  If I feel itchy, I take a hot water bottle and leave it on the skin until it hurts a little bit, and then the itch goes away.  Watch out, though, because you can get burned.  Unfortunately, some people stand under the shower with the water as hot as they can stand it, because it alleviates their itch, so use the hot water bottle instead of that, because it won’t dry out the skin.  I even used to use a blow dryer to the point of getting burned to try and alleviate the itch, but that left the skin even worse off.  Hot water bottles are the best so far.  The Itch Stopper works on that same premise, too, heat, only a hot water bottle covers a lot more territory really quick and is much, much cheaper.

Wet Wraps. Another way to handle the itching is using the Evaporation Method (Wet Wraps).

Vinegar.  Apple cider vinegar kills the itch nicely where hair grows.  Watch, though, because it can horribly sting broken skin.  Dilute it first on broken skin and then work your way up to full strength ... always test small areas first.  It killed sunburn itch when nothing else did.

You Can Get Better, Too ...

My once insane itch that led me to take twenty antihistamines daily is gone.  Thank God not everyone with eczema has this extreme itch, otherwise known as pruritus "severe itching."  So, I avoided as much as possible touching things that made me itch even more like detergents and acidic foods; and, when I did feel itchy from touching something, I rinsed that part of the skin with cold water and tried not to scratch with my fingernails (used my knuckles instead).  

Some people rinse with cool water and then get in front of a fan ... it's very chilly, but can be helpful, too.  

For an in-depth article on itching, see:  American Family Physician on Pruritis ("Itching")

Learn Why Pain Inhibits Itch by Wikipedia