what is the colour of these patches?
they are milky white or its just lighter than your skin?
if it is milky white then it may be vitiligo(leucoderma
).you need mild steroid
if its colour is just lighter than skin it may be pityriasis alba
.you can take some moisturizing facewash or soap for it. apply sunscreen also.
so better to get evaluated by adermatologist nad follow his advice.take care