I suffer from a renal failure since two years. May Allah keep it away from you. Praise be to Allah, I underwent a kidney transplant, and it approximately works 65 or 70 percent. It is well known that the one who underwent a kidney transplant should drink a lot of liquids and regularly take medicine. What is the ruling on fasting in this case?

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

If a trustworthy and knowledgeable Muslim doctor tells you that fasting will negatively affect the transplanted kidney, then it is not permissible for you to fast. Allaah Almighty says (what means): {And do not kill yourselves [or one another]. Indeed, Allaah is to you ever Merciful.} [Quran 4: 29]

If your sickness is not chronic, then you have, after recovery, to make up for the days that you missed in Ramadan. Allaah Almighty says (what means): {So whoever among you is ill or on a journey [during them]—then an equal number of days [are to be made up].} [Quran 2: 184]

However, if your sickness is chronic and incurable, then you have to give food to one poor person for each day that you did not fast.  Allaah Almighty says (what means): {And upon those who are able [to fast, but with hardship]—a ransom [as substitute] of feeding a poor person [each day].} [Quran 2: 184] 

Ad-Daaraqutni reported that Ibn ‘Abbas said regarding the statement of Allah Almighty (which means): {And upon those who are able [to fast, but with hardship]—a ransom [as substitute] of feeding a poor person [each day].}: “This concession is to be used only by the elderly who are not able to fast or those who are chronically ill.” [Ad-Daaraqutni: Saheeh Isnaad]

We ask Allah Almighty to grant you recovery for He is able to do that.

Allaah Knows best.