Coffee, tea and sugar can be harmful; are they haraam like cigarettes?
Question

Some friends and I had a disagreement when we were discussing the prohibition on things that are harmful. The topic of the discussion was smoking, and I quoted as evidence the verse in which Allah says (interpretation of the meaning): “and prohibits them as unlawful Al-Khabaa’ith (i.e. all evil and unlawful as regards things, deeds, beliefs, persons, foods, etc.)” [al-A ‘raaf 7:157]. I said: Everything that is harmful is haraam. They said: Then tea, coffee, cola, sugar and water are all haraam, because drinking too much water may cause death by suffocation, and consuming sugar in very large amounts may elevate blood sugar levels, which leads to shock and causes death. Everything that may be consumed in large amounts and is undoubtedly halaal could still cause harm. What is the guideline on the prohibition on consuming things that may cause harm?.
Praise be to Allah.Firstly: 
We have previously discussed the prohibition on smoking and the reasons for this prohibition in the answers to questions no. 9083 and 10922 
No one should argue about tobacco being evil and haraam. It has a foul odour and has a bad effect on the smoker and the people around him. There is no difference of opinion among doctors concerning the fact that smoking is harmful to the body. Whatever is like this comes under the heading of al-khabaa’ith (that which is evil and unlawful). One of the characteristics of the Prophet (blessings and peace of Allah be upon him) is that he came to permit what is good and forbid what is evil. 
Shaykh ‘Abd ar-Rahmaan as-Sa‘di (may Allah have mercy on him) said: 
Allah, may He be exalted, says to His Prophet Muhammad (blessings and peace of Allah be upon him): “They ask you (O Muhammad SAW) what is lawful for them (as food)” [al-Maa’idah 5:4].
“Say: Lawful unto you are At-Tayyibat (all kind of Halal (lawful and good) foods)” – this refers to everything in which there is benefit or pleasure without it being harmful to the body or mind. That includes all grains and fruits that may be found on farms and in the wilderness. It also includes all sea animals and all land animals apart from those excluded by the Lawgiver, such as carnivores and vermin. Hence the verse implies that khabaa’ith (whatever is bad and unlawful) are haraam, as is clearly stated in the verse (interpretation of the meaning): “he allows them as lawful At-Taiyibat ((i.e. all good and lawful) as regards things, deeds, beliefs, persons, foods, etc.), and prohibits them as unlawful Al-Khabaith (i.e. all evil and unlawful as regards things, deeds, beliefs, persons, foods, etc.),” [al-A‘raaf 7:157].
End quote. 
Tafseer as-Sa‘di, p. 221 
Numerous fatwas have been issued by the scholars concerning the prohibition on smoking. 
The scholars of the Standing Committee for Issuing Fatwas said: 
Smoking is haraam because it has been proven that it is damaging to one’s health, and because it comes under the heading of al-khabaa’ith (that which is evil and unlawful), and because it is extravagance (a waste of money). And Allah, may He be exalted, says (interpretation of the meaning): “and prohibits them as unlawful Al-Khabaith (i.e. all evil and unlawful as regards things, deeds, beliefs, persons, foods, etc.)” [al-A‘raaf 7:157]. 
Shaykh Ibraaheem ibn Muhammad Aal ash-Shaykh, Shaykh ‘Abd ar-Razzaaq ‘Afeefi, Shaykh ‘Abdullah Ghadyaan. 
Fataawa al-Lajnah ad-Daa’imah, 22/178-179 
They also said:  
Smoking is haraam because it comes under the heading of al-khabaa’ith (that which is evil and unlawful), and Allah and His Messenger have forbidden al-khabaa’ith (that which is evil and unlawful). Allah says, describing the Prophet (blessings and peace of Allah be upon him): “he allows them as lawful At-Taiyibat ((i.e. all good and lawful) as regards things, deeds, beliefs, persons, foods, etc.), and prohibits them as unlawful Al-Khabaith (i.e. all evil and unlawful as regards things, deeds, beliefs, persons, foods, etc.),” [al-A‘raaf 7:157].
End quote. 
Shaykh ‘Abd ar-Razzaaq ‘Afeefi, Shaykh ‘Abdullah ibn Ghadyaan. Shaykh ‘Abdullah ibn Munayyi‘
Fataawa al-Lajnah ad-Daa’imah, 22/179, 180 
Thus it becomes clear that quoting the verse “and prohibits them as unlawful Al-Khabaith (i.e. all evil and unlawful as regards things, deeds, beliefs, persons, foods, etc.)” [al-A ‘raaf 7:157] as evidence for the prohibition on smoking is correct. 
There is no disagreement concerning the fact that smoking is something that causes harm to the smoker; indeed it also causes harm to the people around him who inhale the smoke that comes from the cigarette. The basic Islamic principle is that everything that is proven to be harmful is haraam. 
Shaykh Muhammad ibn Saalih al-‘Uthaymeen (may Allah have mercy on him) said: 
The evidence for the prohibition of that which is harmful is to be found in the Qur’aan and the Sunnah. 
From the Qur’aan: 
“and do not throw yourselves into destruction”
[al-Baqarah 2:195] 
“And do not kill yourselves (nor kill one another)”
[an-Nisa’ 4:29]
The prohibition on killing oneself is also a prohibition on the means of doing so. Whatever causes harm is haraam. 
The Prophet (blessings and peace of Allah be upon him) said: “There should be neither harming nor reciprocating harm.” We might also quote as evidence the verse in which Allah says (interpretation of the meaning):
“But if you are ill or on a journey or any of you comes from answering the call of nature, or you have been in contact with women (i.e. sexual intercourse) and you find no water, then perform Tayammum with clean earth”
[al-Maa’idah 5:6].
The point here is that Allah enjoined tayammum for the one who is sick so as to protect him from harm and to offer him an alternative to water, which may harm him if he uses it when it is cold and he is sick and so on. End quote. 
Ash-Sharh al-Mumti‘, 15/12, 13 
Nowadays there is no disagreement that smoking is harmful. 
Shaykh al-‘Uthaymeen (may Allah have mercy on him) said: 
The same applies to smoking, which is harmful in and of itself. The fact that it is harmful is a matter on which doctors are unanimously agreed nowadays, and there is no difference of opinion among them on that score, because tobacco contains toxic substances that damage the blood. End quote. 
Ash-Sharh al-Mumti‘, 15/10 
Secondly: 
As for your friend’s comparing tobacco to permissible food and drinks which may be harmful if consumed in large quantities, this is an invalid argument, because these foods are permissible and beneficial in principle, and are only harmful in certain cases, such as if one consumes too much of them. 
The principle mentioned above, that everything that is harmful is forbidden, also applies in this case. It is not permissible for anyone to drink so much water or eat so many dates – for example – that he will be harmed thereby. 
Shaykh Muhammad ibn Saalih al-‘Uthaymeen (may Allah have mercy on him) said: 
In the case of that which is harmful in conjunction with something else, such as if this food is not compatible with that food, in the sense that if you eat the two foods together it will result in harm, but if you eat them separately that will not result in harm, and the doctor has advised this dietary restriction for one who is sick and has told him, “If you eat it, it will harm you,” then it becomes haraam for him. 
Shaykh al-Islam (may Allah have mercy on him) said: If a person feels that some kind of food will cause him harm or give him indigestion, then it becomes haraam for him. 
If a person says: If I fill my belly with this food, I will need water, and if I add water to it I will hardly be able to walk and it will bother me; and if I sit it will bother me, and if I bow it will bother me, and if I lie on my back it will bother me, and if I lie on my stomach it will bother me. In this case Shaykh al-Islam says:
If he fears that it will harm him, then it becomes haraam for him to eat it. And what he said is correct, because it is not permissible for a person to eat that which will harm him or to wear that which will harm him or to sit on that which will harm him. Even the Sahaabah (may Allah be pleased with them), with regard to prostration, if the heat would harm them, they would spread out their garments and prostrate on them, lest they be harmed and so that they might be at ease in prayer. 
What Shaykh al-Islam mentioned comes under the heading of fear of harm and indigestion, meaning that it is not as a result of the food itself, rather it is the result of consuming too much of it, and even if there is someone who would not be harmed by that, but based on the medical advice that he will be harmed, because if the stomach is filled it will bother him and cause some discomfort…
It was said that one of the harmful things is to eat food on top of other food. If that is correct then it is also haraam, because Allah says (interpretation of the meaning): “And do not kill or murder your own persons. Surely, Allah is, towards you, continuously Merciful” [an-Nisa’ 4:29]. 
It is not far fetched to say that this is correct. As it is something that it tried and tested. End quote. 
Ash-Sharh al-Mumti‘, 15/9-11 
And he said: 
If it is said to a man who has diabetes: Do not eat dates or sweets, then dates and sweets become haraam for him, because they are harmful for him and he has to avoid them, but they are halaal for others. End quote. 
Liqaa’aat al-Baab al-Maftooh, 229, question no. 2 
Thus it becomes clear that your friend’s drawing an analogy between permissible food and drink, and tobacco, which is haraam, was incorrect. 
And Allah knows best.