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You seem to have developed a fungal infection of the back region, which can be either tinea
infection or candidiasis
You should try to keep the back clean and dry .
Do not apply any kind of oils or moisturizing creams over the region .
Wear cotton garments inorder to reduce sweating.
You need to use an antifungal agent like Clotrimazole gel over the affected area twice a day.
Also take oral antifungals .
And to relieve the itching, take oral antihistamines . Dettol
has no role in fungal infections, it might infact irritate the skin further, so do not use it.
The drug that you have mentioned is safe to use and you can take it.
Hope it helps,
Dr Geetika Paul
MD ( Dermatology)