I have a allergies in hand what to do

How to diagnose the cause  the cause of allergies in hand ?
There are many causes and those include:
chemical substance
enviromental factor like humidity
insect bites
Dermatological disease like eczema
urticaria
Side effects of drugs
Systemic illness like liver or gallblader disease
 
What tests should you do ?
firstly skin physical exam ,CBC, inflamatory markers ESR
 
 
How to manage allergies in hand ?
apply moisturizer
avoid itching or scrubbing dry skin
If there is itching and wide space of skin rash in this case you need to use dexamethasone injection and also you need to use topical hydrocortisone 1%
I also recommend to use antihistamine medications like fexofenadin120mg  to easen symptoms.
What is my advice to you ?
you need to consult dermatologist to help you and to follow up treatment