Answer
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
1- Protecting oneself is among the objectives of Shariah and it is given precedence to anything else.
2- Hence, it is permissible to use alcohol-based sanitizers even if they are indisputably impure in case there is no alternative.
Responding to your question, Dr. Rajab Abu Mleeh, Professor of Islamic Studies at Kolej Universiti Insaniah, states:
Necessity has rules. This maxim is significantly considered by the Islamic Shariah. In some cases, due to this consideration, what is utterly prohibited may be rendered lawful. So, if the forbiddance of something is originally controversial, then dispensation becomes more acceptable.
Alcohol was not known for our earlier jurists with its current description and form, and therefore they did not directly tackle the rulings pertaining to alcohol in terms of purity. Rather, jurists tackled the ruling regarding impurity of wine, and since alcohol and wine share the illah (effective cause) of intoxication, some scholars deem alcohol impure too.
In addition, the majority of jurists viewed that wine is classified as a major ritual impurity, just like urine and blood, since the prohibition of it is well established and it is even called abomination. This is stated in the Glorious Quran, {O you who believe! Intoxicants (all kinds of alcoholic drinks), gambling, (sacrificing to) stones set up and (divining by) arrows are an abomination of Shaitan’s (Satan) handiwork. So, avoid (strictly all) that (abomination) in order that you may be successful.} (Al-Maidah 5:90)
However, some other jurists, including Rabi`ah, the Sheikh of Malik; As-San`ani and Ash-Shawkani; Al-Muzni, the disciple of Ash-Shafi`i; An-Nawawi; and others hold the view that alcohol is pure, based on the basic ruling for things. They also interpreted the term abomination mentioned in the verse to be signifying incorporeal ritual dirtiness.
In this regard, an-Nawawi said in Al-Majmu`,
There is no manifest indication (to its substantial impurity) in the verse, since “abomination” according to linguists means dirtiness, and this does not necessitate its impurity. Likewise, the command “avoid that” does not necessarily imply impurity.
He also added,
The nearest (possible) opinion is that mentioned by Al-Ghazali as he said, “It is judged as a major ritual impurity and as a means of deterring people from approaching it, by analogy to the dog as regards that which is licked by it.”
On the other hand, Ash-Shawkani stated in As-Sayl Al-Jarrar,
There is no substantial indication as to the impurity of intoxicants that could be employed as an evidence. As for the verse, namely Almighty Allah’s – Exalted be He – saying, {O you who believe! Intoxicants (all kinds of alcoholic drinks), gambling, (sacrificing to) stones set up and (divining by) arrows are an abomination of Shaitan’s (Satan) handiwork. So avoid (strictly all) that (abomination) in order that you may be successful.) (Al-Maidah 5:90), the word abomination does not denote impurity, but it rather denotes prohibition, as is indicated through the context.
Thus, if wine, which is the basis for the prohibition, is controversial as regards its material impurity, then alcohol is more deserving of being so.
Besides, if wine is impure, and by analogy alcohol is impure too, necessities still make the prohibited things lawful, when one also knows that touching impure substances is permissible in case of need or necessity. A Muslim may touch uncontroversial impurity during istinja (cleansing the private parts after urination or defecation), and a physician may touch blood when performing surgical or childbirth operations.
In the past, the person who used to perform cupping would draw out blood with his or her mouth and then spit it out, and the Shariah did not forbid such act.
Furthermore, alcohol is among the highly volatile substances that quickly vaporize, and in turn, there is no harm in using it.
Eventually, protecting oneself is among the objectives of Shariah and it is given precedence to anything else. Hence, it is permissible to touch alcohol even if it is indisputably impure in case there is no alternative means of protection but it. Protection against disease is among the aims that we are commanded to pursue by our honorable Shariah.
Almighty Allah knows best.