Is Vaping Allowed?
Question

1- Vaping which refers to electronic shisha, electronic cigarettes or shisha pens is haram because the reason for which smoking by traditional means is haram is also applicable in all these cases. 
2- If vaping contains natural flavourings and does not contain any haram substances and is not harmful to the users or others, then it is not haram to use it. For more, please see the detailed answer.
Praise be to Allah.What is electronic shisha? 
Recently what is known as “electronic shisha” or “electronic cigarettes” or “shisha pens”, or other names, have become widespread. Those who use them say that they are alternatives to the traditional narghile (hookah or shisha) and to cigarettes. They claim that they are healthy, based on the process by which the vapour is produced, instead of tobacco smoke that is produced by the traditional narghile ; it turns the liquid inside the tube into vapour. The liquid that is used is free of tobacco and tar, and similar harmful substances, and the flavours given to this liquid are natural; mint, apple, orange and other fruit flavours are added to it. 
But medical evidence proves the opposite of that and shows that all of these things have a harmful effect on the lungs and brain. 
Origin of electronic cigarettes
The idea of the electronic cigarette began several years ago in China, after major international organisations, such as the World Health Organisation, launched many campaigns against traditional smoking practices, and restrictions on smoking were imposed in workplaces, airports and other public places. The major tobacco companies in China looked for a new way to market their products, via so-called electronic cigarettes. Then this idea spread to other countries in the world. 
How electronic cigarettes work
The electronic cigarette uses a lithium battery in the form of a cigarette which can be recharged like a cellphone battery. A capsule is placed inside it that contains a certain amount of nicotine that varies in amount from one capsule to another, in addition to other substances and various flavourings such as coffee, mint, vanilla, and strawberry. 
Are electronic cigarettes healthy?
In fact, electronic cigarettes are not a healthy alternative to cigarettes. They have been opposed by the World Health Organisation and the US Food and Drug Administration. 
Moreover, they are very expensive, with prices similar to those of regular cigarettes, so this is not a remedy that everyone can use to help give up smoking gradually, as the marketing companies claim. 
The US Food and Drug Administration has stated that even in the case of electronic cigarettes that are claimed to be free of nicotine,  laboratory tests have proven that nicotine is present in them, as well as nitrosamines, substances which are medically known to be carcinogenic. They also contain glycol, which is a toxic substance that is used in antifreeze for cars. 
A recent study carried out at St Michael’s Hospital in Toronto stated that cigarettes flavoured with mint may be more dangerous with regard to causing strokes, in comparison to other kinds of cigarettes, especially in women and fair-skinned people. Researchers found that the risk of stroke in those who smoked mint flavoured cigarettes was two times greater than in those who smoked ordinary cigarettes.
Hence some states have banned the sale, marketing and importing of electronic cigarettes, such as Australia, Canada and Brazil. 
To sum up, electronic cigarettes should be treated in the same manner as traditional cigarettes at all levels. They are not a means of giving up smoking , as some companies suggest. The risk of harm is much greater than the alleged benefits. 
A representative of the World Health Organisation’s Tobacco Free Initiative said, addressing journalists: It is 100% wrong to issue claims that electronic cigarettes offer a safe remedy that helps smokers give up the habit. He further added: These cigarettes contain a mixture of chemical substances that are very toxic.
Is vaping haram?
Once it is proven that these new kinds of cigarettes contain harmful substances and that the harm they cause is like or similar to or greater than that of ordinary cigarettes, then there is no difference between the two with regard to the rulings that they are forbidden. 
After establishing this, no one should be deceived by so-called “electronic shisha” or “electronic cigarettes” or “shisha pens” and the like, because the reason for which smoking by traditional means is haram is also applicable in all these cases. 
But if there are types that are proven, by means of examinations and laboratory tests carried out by trustworthy scientists, to contain natural flavourings only, and they do not contain any haram substances and are not harmful to the users or others, then in that case it is not haram to use these safe kinds. The ruling depends on whether the reason for it is present or not. 
What is required of the Muslim in such cases is to leave that which makes him doubt for that which does not make him doubt, and to avoid dubious matters, so as to protect his religious commitment and his honour. In that which Allah has permitted to him of good and halal things there is sufficient so that he has no need of that which is haram or that concerning which people are uncertain about the ruling. 
For more information, please see the answer to question no. 127312
And Allah knows best.