Is it permissible for the bile of permissible animals to be eaten to treat asthma? Hope for your answer.
Alhamdulillah, praise and gratitude to Allah SWT for His countless blessings for us all. Praise and salutations to our beloved Prophet Muhammad PBUH, his family, companions, and all those who follow his footsteps until the Final day.
We begin with the statement of Allah SWT:
يَا أَيُّهَا النَّاسُ كُلُوا مِمَّا فِي الْأَرْضِ حَلَالًا طَيِّبًا
“O mankind, eat from whatever is on earth [that is] lawful and good,” 
This verse is dedicated to all mankind, regardless of whether they are believers or not, to eat whatever that is on this earth from grains, fruits and animals that is halal for them to take (which means food that is eaten and benefitted from), not taken through force, stealing, prohibited muamalat (trade) or other prohibited matters. While the word ‘tayyiban’ means not from something bad (dirty and disgusting) such as carcass, blood, pork and others. Thus, the verse is evidence that the original ruling for anything (to be eaten and benefitted from) is permissible. 
Definition of Bile
Bile is a fluid secreted by the liver. Bile helps the body digest and absorb fatty foods. It also removes certain waste products from the body. The liver secretes bile continuously, producing about a litre a day. Bile flows from the liver into a tube known as the hepatic duct. This tube connects to the common bile duct, which leads to the small intestine. Except after a meal, most of the bile does not go directly to the intestines. Instead, it enters the gallbladder, a sac that attaches to the common bile duct. There, bile is stored and concentrated until needed.
Bile contains a variety of wastes that eventually become part of faeces (body solid wastes). One of these wastes, bilirubin, is formed as a result of the breakdown of red blood cells. Bilirubin combines with fat-soluble chemicals in the liver to form a product released in the bile. Bilirubin gives colour to bile, which varies from brown to greenish-yellow. Other wastes in the bile include excess cholesterol and certain toxins eliminated by the bile from the bloodstream. 
The ruling of slaughtered animal parts
Abu al-Husain Yahya bin Abu al-Khair stated that nothing from the parts of a permissible animal become najis due to the slaughter. Consequently, we are permissible to take benefit from its meat, bones, fur, vein and others as long as it is not najis. 
Furthermore, in al-Mausu‘ah al-Fiqhiyyah al-Kuwaitiyyah it is stated without a doubt shows that the slaughter of a permissible animal is permissible to be eaten, the whole animal is permissible to be eaten – which means all of its parts on the condition that there is no evidence stating otherwise.
The ruling of bile
In a fatwa by Syeikh al-Ramli, he once discussed whether the bile of slaughtered permissible animal is considered pure or not? He answered that it is ruled najis because it has changed in the internal organs of the animal similar to blood; which is the liquid within it. As for the bile itself (what is meant here is the gallbladder itself) is pure, for it can be eaten because it is a part of the permissible animal to be eaten, slaughtered, although its contents are considered mutanajjis (which means it needs to be cleansed before it is cooked and eaten). 
Not only that, but Syeikh ‘Abd al-Rahman al-Jaziri also cited the opinions of scholars from madhhab Syafi’i, who are of the opinion that the bile liquid is najis, while the gallbladder is considered mutanajjis (something that has come into contact with najis) and will be considered pure again after it is washed the same as other organs such as the stomach. The reason is the liquid in it is najis and this makes it mutanajjis, due to the liquid. Hence, it will return to being pure after it is washed (to remove the najis in it). 
Medicating using najis
Regarding this matter, there is a hadith narrated by Ummu Salamah R.Anha, where Rasullullah PBUH said:
إنَّ اللَّهَ لَـمْ يَجْعَلْ شِفَاءَكُمْ فِيمَا حرَّمَ عَلَيْكُمْ
“Allah did not make your cure in what He made Haram (unlawful) to you.” 
Furthermore, there is also another hadith as narrated by Wa’il al-Hadrami, where Tariq bin Suwaid al-Ju‘fi R.A asked the Messenger PBUH regarding wine. Then, the Prophet PBUH restricted it – or he disliked doing it. – Tariq said: “Indeed, I only use it for medication.” The Prophet PBUH replied:
إِنَّهُ لَيْسَ بِدَوَاءٍ، وَلَكِنَّهُ دَاءٌ
“It is not a medicine, but is a disease.” 
Imam al-Nawawi when commenting on the ruling of medicating with najis, he explained the opinion of madhhab Syafi’i and the majority of scholars saying that it is permissible to use najis that are not intoxicating as medication or treatment. However, this permissibility is bound with the unavailability of other pure and permissible medicine or treatment to be used. If there are other pure and permissible medicines, then it is prohibited to use najis as medication without any khilaf. 
According to the above arguments and discussions, we can conclude several matters:
- Bile is prohibited to be consumed because it is najis and contains various waste materials that can endanger the body such as excessive cholesterol and toxins that are excreted from the blood circulation.
- While for the gallbladder that stores it is considered as mutanajjis (something that came into contact with najis) and is included as a part of the animal that is permissible to be eaten. However, it is on the condition that it is first washed and cleaned removing the najis, the same to other organs such as the stomach. The reason is it will return to its original ruling of slaughtered animal or an animal that died according to syarak, of which all of its body parts are permissible and can be benefitted from, whether it is to be eaten or others, as long as there is no evidence stating otherwise.
- Medicating using najis is only allowed in the situation when there is no other pure substance that can replace it as a cure. If there are other substances to replace it, then it is prohibited for it to be used as medication or treatment.
May Allah SWT give us all a clear understanding in religion. Ameen.
 See world Encyclopaedia, Trans. DBP, 8/239.
 See al-Mausu‘ah al-Fiqhiyyah al-Kuwaitiyyah, 5/153.
 See Fatawa al-Ramli, 1/72.
 See al-Fiqh ‘ala al-Mazahib al-Arba‘ah, 1/10.
 Narrated by Ibn Hibban (1391)
 See al-Majmu‘ Syarh al-Muhazzab, 9/50-51.