Hi, welcome to the forum, itching arms seems secondary to allergy known as atopic dermatitis and also other strong possibility is irritant dermatitis. Remember if you have been exposed to any chemical (detergent, shampoo etc.) or certain garments which might have caused irritant dermatitis. if it is present, Avoiding these situations is helpful for acute flares as well as for long-term management. Sunlight and sweating can be precipitating factors.
Other causes for itching are worm infestations like ascaris and liver flukes, cholangitis and biliary stasis, thyroid disorder and delusional parasitosis.
I suggest you to get the following parameters checked like liver function, thyroid function and absolute eosinophil count. Treatment includes anti histaminic and glucocorticoids against prescription. Apply moisturizing agents to prevent dryness of the affected skin. Take a bath before sleeping, so as to shred the allergens.
I suggest you to consult a skin specialist. Take care and regards.
I have had this condition for 9 years now. This year seems to be a bad one again. I am outdoors a lot. This year my left arm is worse. When it is really bad I put ice on to the point it burns my skin and numbs the itch. This helps. I've been reading about "witch hazel" helping when the tingling begins so will pick some up today. I find most creams and ointments just make the itch worse. The nuero thing makes sense. My neck and shoulders are pretty messed up from work (I am a dentist) and martial arts. Does anybody else have neck and shoulder issues? I guess the proffesionals have termed this condition as "brachioradial pruritus.
This has also been a problem for me off and on since I had mono in 2001 and got the milk of the yarrow plant on my arms. Currently my doctor has sent me to the gastro to get my stomach and colon checked out. They are looking for Celiacs disease. For me, I do really believe it's related to both allergies and cervical spine misalignment, which I just learned could be the reason today as I googled... Good luck to you in finding the cure. It is difficult to live with and we have to keep searching for our own answers.