Please note that you should get
Malaria/Dengu/Typhoid/CBC/LFT test done first to diagnose the cause of fever.
At the time of fever--
Soak a washcloth in cool tap
water, wring out the excess water and then sponge areas like your armpits, feet, hands and groin to reduce
Also, you can place cold, damp washcloths on your forehead and the back of your neck. The cloth pieces should be changed regularly after a few minutes. This remedy is beneficial when dealing with a high fever as it helps keep temperature under control.
You can also take a bath in lukewarm water to relax your body. Taking a shower, however, may not be a good idea. Plus, needless to say, take as much rest as possible as it helps the body fight the illness.
Note: Do not use very cold water as it may cause the internal body temperature to increase.