Hi Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concern.
Itchy rashes on the inner parts of forearms, knees and thighs can be due to many reasons. Their treatment also depend upon causative agent.
1 Mostly it is due to friction between body parts. Maintain hygiene as this is very important in preventing these rashes. Hydration of the skin should be maintained by moisturizing creams. Use loose clothes to wear.
2 Rashes due to
allergic reaction. Anti-allergic medicines like benedryl/
cetrizine may be helpful. It may be also due to some drugs.
3
Psoriasis, impetigo and eczema are few of the diseases that are known to produce rashes or skin eruption.
4
Fungal infection can also lead to rashes. It is more common in individuals with immunodeficency. Antifungal cream/ lotions like
clotrimazole may be helpful in these cases
If problem persist, visit a dermatologist
Hope your query is solved
Get well soon