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:
You should do what you are able to do, as follows:
1- Stop taking the medicine altogether in Ramadan;
2- Take it at the beginning of the night;
3- Take it before going to sleep, and put up with the hardship of hunger and thirst during the day, if that will not harm you;
4- If you fear that you may be harmed or die of hunger or thirst, then you may break the fast by eating or drinking enough to ward off death, then you must make up the day later on.
The Ramadan fast is obligatory upon every accountable Muslim who is able to fast.
If a Muslim is unable to fast because of a sickness that will harm him or cause great hardship for him if he does fast, or he needs treatment during the day in Ramadan in the form of pills, liquids and other things that are eaten or drunk, then in his case it is prescribed not to fast, because Allah says:
{…and whoever is ill or on a journey – then an equal number of other days. Allah intends for you ease and does not intend for you hardship.} (Al-Baqarah 2:185)
The Prophet (peace be upon him) said: “Allah loves for His concessions to be followed as He hates to be disobeyed.” (Ahmad and classed as saheeh by al-Albaani in Irwa al-Ghaleel)
If you can avoid taking this medicine during the month of Ramadan, without causing harm to yourself or obvious hardship, then you should stop taking it so that you will be able to fast.
But if not taking this medicine will be harmful to you, or will cause you obvious hardship, then you may take it at the beginning of the night, so that it will not affect your fast on the following day.
If you have no alternative but to take it before sleeping, and that will result in extreme hunger and dryness of the mouth during the day, then you should form the intention to fast from the night before, and start your day fasting, then if you fear that you will be harmed or die as a result of that, it will be permissible for you to break the fast by eating or drinking as much as will ward off the harm, then you should refrain from eating and drinking for the rest of the day, and make up that fast later on.
If you do not fear that you will be harmed or die, then it is forbidden for you to break the fast.
Your case is like that of one who experiences severe hunger and thirst because of his work, such as a baker, blacksmith, construction worker and so on.
It says in Kashshaf al-Qinaa‘ (2/310):
“Abu Bakr al-Aajurri said: Whoever does physically demanding work, if he fears that he will be harmed by fasting, he may break the fast and make it up later on, if he will be harmed by not doing his work. If he will not be harmed by not doing his work, then he is sinning if he breaks the fast, and he should stop doing his work. Otherwise, if he will be harmed by not doing his work, then he is not sinning if he breaks the fast, because he has an excuse.”
In al-Mawsu`ah al-Fiqhiyyah (28/57), it says:
“The Hanafis said: With regard to a worker who needs to earn his livelihood, such as a baker or harvester, if he knows that he will face harm by doing his work, it is permissible for him to break the fast, but it is haram for him to break the fast before he encounters hardship.”
In Fatawa al-Lajnah ad-Daa’imah (10/ 233), it says:
“It is not permissible for one who is accountable not to fast during the day in Ramadan just because he is working.
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But if he encounters great hardship that compels him to break the fast during the day, he may break the fast by eating and drinking as much as will ward off hardship, then he should refrain from eating and drinking until sunset, then he may break the fast with the people, and he must make up the day on which he broke the fast.”
We ask Allah to heal you and grant you well-being.
Almighty Allah knows best.
Source: www.islamqa.info