I.
In principle, it is prohibited to concume that which will harm a person, such as poison, tobacco and other things that are definitely proven to be harmful.
Shaykh Zakariya al-Ansari said in Asna al-Matalib, 1/569: It is prohibited to consume that which causes harm, such as stones, soil and mud. It states definitively in Al-Muhadhdhab that such things are prohibited, and the same was stated by al-Qaffal, al-Qadi Husayn, al-Fakhr ar-Razi and a number of others. Ibrahim al-Mirwadhi said: We should regard it as definitely prohibited if its harm is proven.
As-Subki said in the chapter on riba in his commentary on Al-Minhaj: It is not prohibited to eat mud, because there is no sound hadith to that effect, unless eating too much of it becomes harmful, in which case it is prohibited. End quote.
It says in Kashshaf al-Qina`, 6/189: It is not permissible to eat anything that is harmful, such as poison and the like, because Allah, may He be Exalted, says: {and do not throw [yourselves] with your [own] hands into destruction} [Al-Baqarah 2:195]. And in At-Tabsirah it says: What is harmful in large amounts is permissible if it is consumed in small amounts, so it is permissible to consume a small amount of scammony [Convolvulus scammonia – a type of bindweed the roots of which may be used for medicinal purposes], saffron and the like, if that will not cause harm, because there is no reason to forbid it. End quote.
Shaykh Ibn `Uthaymin (may Allah have mercy on him) said: The evidence for the prohibition on that which may cause harm is to be found in the Quran and Sunnah. In the Quran, Allah, may He be Exalted, says: {and do not throw [yourselves] with your [own] hands into destruction} [Al-Baqarah 2:195] and {And do not kill yourselves [or one another]} [An-Nisa’ 4:29]. The prohibition on killing oneself is also a prohibition on the means that may lead to that. So everything that leads to harm is prohibited.
The Prophet (blessings and peace of Allah be upon him) said: “There should be neither harm nor reciprocating harm.” Perhaps that is also indicated by the verse: {But if you are ill, on a journey, or have relieved yourselves, or have been intimate with your wives and cannot find water, then purify yourselves with clean earth} [Al-Ma’idah 5:6]. The proof in this verse is that Allah, may He be Exalted, has made it obligatory for the one who is sick to do tayammum [purify himself with clean earth] to protect him from harm. Thus He has given him an alternative to water which could harm him if he used it when it is cold or he is sick and so on. End quote from Ash-Sharh al-Mumti`, 15/12.
Similarly, it is prohibited to consume anything that could cause harm by eating it in particular, such as forbidding a sick person to eat a particular food because it could harm him. In that case, it becomes prohibited – specifically for him – to eat it.
Shaykh Ibn `Uthaymin (may Allah have mercy on him) said: Some foods may be permissible to one person and forbidden to another. If it is said to a man who has diabetes: Do not eat dates or sweets, then dates and sweets become prohibited to him, because they are harmful for him and he must avoid them, although they remain permissible for others.
End quote from Liqa’ al-Bab al-Maftuh, 229/7.
II.
If a food is beneficial in principle, but it is mixed with something that could be harmful if eaten in large quantities- such as crops on which pesticides have been used, and the like; and flour, sugar, tea, coffee and other things that could cause harm if consumed in large quantities – we should not say that they are completely prohibited; rather the prohibition applies to one who consumes a large amount of it, or one for whom consuming it will definitely be harmful in his case.
Shaykh Ibn `Uthaymin (may Allah have mercy on him) said:
His saying “foods that are not harmful” excludes pure foods that are still harmful, because pure foods that are harmful are not permissible; rather they are prohibited, whether the harm is in a particular food itself or occurs when it is added to something else.
An example of something that is forbidden to consume in and of itself is poison, because it is harmful in and of itself. The same applies to tobacco; it is harmful in and of itself, and its harm is something on which doctors are unanimously agreed nowadays, and no two doctors disagree on that, because of what it contains of toxic substances that damage the blood.
An example of that which is harmful when added to something else is when one food is not compatible with another food, meaning that if you put the two foods together, they will cause harm, but if you eat them separately, they will not cause any harm. This is like when a sick person is on a restricted die and is told not to eat a particular type of food, and it is said to him: If you eat that, it will harm you. In that case it becomes prohibited for him …
Shaykh al-Islam (may Allah have mercy on him) said: If someone feels that there is some type of food that may harm him or cause him indigestion, it becomes prohibited for him.
So if someone says: If I fill my stomach with this food I will need to drink water, but if I add water to it I will not be able to walk, and if I sit down I will feel uncomfortable, and if I bow I will feel uncomfortable, and if I lie on my back I will feel uncomfortable, and if I lie on my stomach I will feel uncomfortable – regarding that, Shaykh al-Islam said: If he fears harm, then eating that food becomes prohibited for him. And what he (may Allah have mercy on him) said is true, because it is not permissible for a person to eat that which will harm him, or wear that which will harm him, or sit on that which will harm him. Even the Sahabah (may Allah be pleased with them), if they feared that the heat could harm them when they prostrated [because the ground was too hot], they would spread their garments and prostrate on them, to avoid harm, and so that they could be at ease in their prayer.
What Shaykh al-Islam mentioned about fear of harm and indigestion, has to do with harm that is due to something else, which is eating too much. In other words, the food in and of itself is not harmful, but eating too much of it will cause harm, even if the person does not feel it. But what appears to me to be the case, from a medical point of view, is that he will be harmed, because when you fill the stomach, you will feel uncomfortable or tired. And it was said that one of the things that would destroy a person’s health is eating again soon after eating. If that is the case, then it is also prohibited, because Allah says: {And do not kill yourselves [or one another]. Indeed, Allah is to you ever Merciful} [An-Nisa’ 4:29].
It is not far-fetched to say that this is true, as it is something that is known from experience.
End quote from Ash-Sharh al-Mumti`, 15/9-11.
For more information, see the answer to question no. 118268.
Conclusion
What is definitely harmful for everyone is prohibited to consume, but if it is harmful to one specific person, then it is prohibited for him.
Whatever is not definitely harmful is not prohibited, and the same applies to that in which there is slight harm, or there is harm, but that harm is removed when it is added to other foods. If that is the case, we cannot say that these things are prohibited, because in principle things are permissible and with most foods, if you check them today, you will find something harmful in them, so to suggest that it is prohibited to consume them will cause a great deal of hardship to people, and no one says that, praise be to Allah.
And Allah knows best.
