Limitations on Fasting

Kidney donors and fasting

Following a kidney donation, the donor’s remaining kidney undergoes a process of development and growth, in order to ‘compensate’ the body for the absence of the kidney that was removed. During this period, dehydration must be avoided, so that the body can regain its strength. For this reason, doctors recommend that donors do not fast for the initial period following the kidney donation.

Medical opinion is divided as to how long this initial period lasts, but the consensus is that the donor can fast as usual from one year after surgery.

After consulting medical specialists and senior rabbinic authorities (poskim), our recommendations are as follows:

Yom Kippur

A year or more after a kidney donation, the donor can fast as usual. However, since he must avoid dehydration, he must stay out of the sun and refrain from physical exertion. It is advisable to stay in air-conditioned surroundings.

If less than a year has passed since the donation, the donor must drink one and a half liters of fluids in the halachically-defined manner (i.e. le’shiurim).

For more detailed instructions (formulated by Rav Heber) for donors and recipients, press here.

Tisha B’Av

According to medical specialists in Israel and senior rabbinical authorities, a person who has donated a kidney within the last year must not fast on Tisha b’Av. From a year onward, he can fast as usual (unless he has any special problems). Kidney donors must be careful not to dehydrate, so they must refrain from physical exertion and exposure to heat, and try to stay in air-conditioned surroundings.

For more detailed instructions for donors and recipients, press here.