An excerpt from "Tibb un Nabawiyy".

وَقُلْ رَّبِّ أَدْخِلْنِي مُدْخَلَ صِدْقٍ وَأَخْرِجْنِي مُخْرَجَ صِدْقٍ وَاجْعَل لِّي مِن لَّدُنكَ سُلْطَانًا نَّصِيرًا

It has been narrated in the Sahihian that the Prophet said:

ثبت فى "الصحيحين": عن نافع، عن ابن عمرَ، أن النبى صلى الله عليه وسلم قال: "إنَّمَا الحُمَّى أو شِدَّةُ الحُمَّى مِنْ فَيحِ جَهنمَ، فَأبْرِدُوُهَا بِالْمَاءِ
Verily fever; or severe fever is a breath of the Hell Fire, so cool it using water.

This Hadith has caused confusion for many ignorant doctors as they thought it contradicts the common method of treating fever. We will explain this Hadith in detail Insha'Allah. When the Prophet issues a statement, it is either general for all people or for specific people and conditions. The majority of the Prophet’s statements are of the first type. As for the second type, it is similar to the Prophet’s statement:

‏‏لا تستقبلوا القبلة بغائط، ولا بول، ولا تستدبروها، ولكن شرقوا، أو غربوا
"Do not face the Qiblah with urine or feces, nor leave it directly behind you. Rather, face either the East or the West".

This statement (facing the East or the West) is not for those who reside in the East, the West or Iraq, but for those residing in Madina al Munawwarah and Ash-Sham (Syria). It is the same case with the Prophet’s statement:

‘What is between the East and the West is a Qiblah.

Understanding this fact, we can realize that what the Prophet said regarding fever is particularly for the people of Hijaz (Western Arabia), for the people in this area are susceptible to a type of fever that results from sunstroke. This type of fever requires cold water, either by drinking it or taking a bath. Fever causes rising temperatures in the body that spreads out from the heart and which spreads throughout the entire body via the blood vessels and the soul, which disrupts the proper functioning of the body.

There are two types of fever, accidental that is a result of tumors, sunstroke, movements, or intense heat and another type that results from an ailment that usually starts at a particular organ and then heats up the entire body. When the fever is of the first type, it ends in one to three days. If the fever is a result of harmful mixtures, it is called septic (or toxic) fever, which is divided into four types: bilious, melancholic, phlegm and sanguinary. If the fever originates in the basic organs of the body, it is called hectic fever, which has many types in addition.

The body benefits from the fever more so than it benefits from taking medicine. This is because the fever heats up and matures harmful substances, which it could not have done without the fever. In addition, fever causes various blockages to open especially those that medicines can not reach.

As for simple and chronic conjunctivitis, fever helps cure most of its types quickly, as well as, helping against facial paralysis, hemiplegia, paralysis affecting only one side of the body, spasms and many other ailments that result from thick substances or excesses. Some of the best doctors feel a bit relieved when fever breaks out in an ailing body, just as the sick person rejoices upon recovering from illness. This is because fever is more efficient than medication in some cases, since it matures the spoiled and septic substances that harm the body. When such substances reach maturity, the medicine will reach it, as the substances are ready to be discarded out of the body, concluding this process. Thus, the fever becomes a part of the cure.

Based on these facts, it appears that the Hadith is talking about the accidental type of fevers that are relieved by being submerged into cold water or by drinking cold water. In this case, the sick person does not need any other medicine, because this type of fever is composed of heat that is connected to the soul. When a cold substance is introduced, the heat produced by the fever will be eliminated without having to get rid of any mixtures of substances or to wait for these substances to mature.

Galinus, one of the renowned doctors, admitted that cold water helps relieve this type of fever. He stated in the tenth article of his book, Healing Methods, “If a young, healthy man, who does not suffer from an internal tumor, took a bath in the heat of the day or swam in it, he will gain a benefit,” He in addition stated that he used to prescribe this remedy on a regular basis. In addition, Ar-Razi said in his book, Al-Kabir:

‘If the strength is normal, but the fever is very intense and the maturity (of the harmful substances) is apparent, while not suffering from any internal tumors or any type of ruptures, then drinking cold water becomes beneficial. If the ailing person is fat, the weather is hot and the person is used to taking cold showers, let him do just that.”

Regarding Prophet’s statement that "fever is a breath of fire", there are two possible meanings.

First, the fever is a breath that was released from Hell so that the slaves are aware of it and thus learn a lesson from this fact. Therefore, Allah has created reasons and causes for the fever to appear and breakout. Similarly, comfort, joy, enjoyment and happiness are a part of Paradise’s joys that Allah has Allowed to appear in this world (as an example and a lesson), and He Has Allowed such feelings to be connected to reasons and causes behind their appearance.
Secondly, the Hadith equated fever and the heat of day, to the intense heat of Hellfire, so that our hearts could imagine the intense anguish of the Fire and the heat that emits from it.

The Prophet’s statement, ‘Cool it off with water might entail all types of water, and this is the correct opinion. Another opinion states that the water here means Zam Zam water. Supporters of this opinion used as evidence what Al-Bukhari narrated in his Sahih that Abu Jamrah, Nasr bin Imran Adh-Dhuba'i said, I used to be in the presence of Ibn Abass in Makkah until one day, I was struck by fever. He said to, ‘Cool it off with Zam Zam water, for the Messenger of Allah said:

"Fever is a breath of Hell’s fire, therefore, cool it with water, or said with Zam Zam water.”

The narrator of the Hadith was in doubt as to the exact words of Prophet Muhammad Sall Allahu ‘alaihi wa Aalihi wa sallim. Otherwise, it would be established that the Prophet meant Zam Zam water for the people of Makkah, because it is available. All others can use whatever water is available to them.

There is a difference of opinion concerning if Prophet Muhammad Sall Allahu ‘alaihi wa Aalihi wa sallim meant by this Hadith to encourage giving away some water as a charity, or to actually use it. The correct opinion is that the Hadith means using it. I believe that those who understood the Hadith as giving some water as a charity did not understand the goal behind using cold water for fever. Yet, there is a good explanation for our beloved Prophet’s statement, for the reward is of a type comparable to the deed. Since thirsty people drink cold water to quench their thirst, Allah Dissipates the fever with cold water as well. Yet, this is an implication of the Hadith, as for the ruling contained in it, it simply means to use the water (not give it away in charity).

Abu Nu'aym said, Anas narrated that Prophet Muhammad Sall Allahu ‘alaihi wa Aalihi wa sallim said :

“If any of you comes down with fever, let him sprinkle cold water on himself for three consecutive nights before the day breaks.

Ibn Majah narrated that Abu Hurayrah Radhi Allahu ‘anh related from Prophet Muhammad Sall Allahu ‘alaihi wa Aalihi wa sallim that he said :

‏‏الحمى كير من كير جهنم، فنحوها عنكم بالماء البارد

‘Fever is a bellow of Hells heat. So remove it from you with cold water.’

It is also narrated in the Sunan that Abu Hurayrah said:

‘Fever was mentioned in the presence of the Messenger of Allah and a man cursed it. The Messenger of Allah said:

‏‏لا تسبها فإنها تنفي الذنوب، كما تنفي النار خبث الحديد

‘Do not curse it, for it removes the sins, just as fire removes the impurity of the iron.” [Refer to Sahih Muslim].

Fever is usually followed by a diet avoiding improper foods and requires consuming beneficial foods and medicines. The sick person’s body will be cleansed from all impurities and septic elements and materials, having a similar purifying effect as the fire has when it removes the impurity of the iron. The benefits that fever has are already known to the medical authorities.

As for cleansing the heart from its ills and impurities, only doctors of the heart (this does not refer to cardiologists) have access to this type of knowledge. Such experts will find that whatever the Prophet stated in this regard is the plain truth. However, when the heart's sickness become chronic, hope diminishes that it will ever be cured. Fever thus helps the body and the heart. Therefore, cursing such a beneficial matter would be an act of injustice and transgression.

Abu Hurayrah Radhi Allahu ‘anh said :

ما من مرض يصيبني أحب إلي من الحمى، لأنها تدخل في كل عضو مني، وإن الله سبحانه يعطي كل عضو حظه من الأجر

“No ailment that I might suffer from is dearer to me than fever, because it enters every organ of my body, and Allah Gives each organ its due share of the reward.

Therefore, using cold water to relieve fever during summer and in hot areas is beneficial, because the water would be the furthest from the rays of the sun just before daybreak (at it is the coolest at this time). In addition, just before daybreak, the body is at its strongest, for the ailing person would have taken his due share of sleep and relaxation In addition they would have less polluted air to breathe. The strength of the body will be added to the strength of the medicine; water in this case and they will both relieve the fever that is not a result of malignant tumors or septic substances or conditions. Allah will then extinguish the heat of the fever by His will.