Answered by: Maulana Mujahid Hussain
Narrated/Authority of Abu Hurairah: Mention of fever was made in the presence of the Messenger of Allah (saw), and a man cursed it. The Prophet (saw) said: 'Do not curse it, for it erases sin as fire removes filth from iron. (Ibn Majah Hadith No: 3469)
Does this mean we should not try to cure fever since more of our sins will be erased?
And in Hadith No: 3471 of Ibn Majah, Aisha RA narrates that the Prophet (saw) said: "Fever is from the heat of the Hell-fire, so cool it down with water."
With similar narrations for Ibn Umar, Rafi bin Khadij, Asma bint Abu Bakr and even Abu Hurairah himself narrates that the Messenger of Allah (saw) said: "Fever is one of the bellows of Hell, so avert it from yourselves with cold water." (Ibn Majah Hadith No: 3475)
The answer to your first question :
We should look for cures and it is mustuhub to treat ourselves when we fall ill. It is narrated by Abu Hurairah (radi Allahu anhu) that the Prophet Sallallahu Alahi Wasalam said: “There is no disease that Allah has sent down except that He also has sent down its treatment.” (Sahih Bukhari)
The meaning of the first hadith is Allah rewards us for our patience in the illnesses by elevating our ranks or by expiating our sins.
As for your second question :
The scholars mention this is specific to fevers found in the Middle East or hot climates. There have been many kinds of research which established the benefit of having a cold shower when one has a fever in those lands.
If you can understand Arabic then please read the following articles :
Only Allah Knows best.
Written by Maulana Mujahid Hussain.
Checked and approved by Mufti Mohammed Tosir Miah
Darul Hadith Birmingham