Hello My wife 43 years started having red pimples...

What's the cause of pimples
Genetic factor
Fatty substances produced by the glands
diet contains fat
Hormonal imbalance.
Psychological factor
Lack of personal hygiene
Humidity
Persistent sweating
Tension
What is the treatment of allergic rash ?
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.
if you have a systemic disease causing itching you should see an internist
To treat pimples for different reasons follow these tips:
Wash with warm water then cold water
Moisturizing Creams.
steam bath.
Honey mask.
Stay away from foods that contain fatty substances such as fast food and chocolate
Use vit A derivative Isoterntoin , but whith extreme caution due to its bad effect on pregnancy and liver
Use microdermabrasion
Use benzoyl peroxide
Use sulfur soap or antiseptic soap
Do not put  fragrance contains alcohol which increases the secretion of fat cells.
 peeling the skin with peeling creams such as fruit acids that help blackheads peel off, it may be useful.
Or by laser and this process is done by directing specific waves of light on the skin to peel layer after layer through evaporation of damaged cells and remove the effects that resulted from acne or blackheads

Mostly if it is viral infection it came on hands foot and exposed part of body 
Just continue to use dermovate 
BEPANTHINE cream 

Please send its picture to this email
doctor.jawabkom@gmail.com 
Well you must use this cream 
Salisayclic acid 
Benzoic acid 
And you need to take zyrtic tab once daily 
Beneocyn cream 3 times daily 
Green tea oil 
Ali Vera oil. Mint oil 
You should excluda out eczema and atopic dermatitis 
Or ganglion cyst 
Acne 
Abscess 
Warts