What is the ruling on a woman treating a man, and vice versa?

The questioner : Yes, it is permissible for a woman to treat a man if no male doctor is available to treat him. How is it that a woman treats a man and a man does not treat a woman? Come, let us proceed.

The Shaykh : Well, it is permissible for a woman to treat a man if no man is available to treat the man, because that is a pressing need. So if this patient comes to the hospital and we do not find a man to treat him, there is no blame on the woman treating him, but on the condition that she does not be alone with him, because a woman being alone with a man is forbidden, based on the saying of the Prophet (peace and blessings be upon him) . So it is not permissible for a man to be alone with a woman, even if he is a relative of her husband; he does not be alone with her. But one of the most amazing things I have seen is that some scholars said regarding the saying of the Prophet (peace and blessings be upon him), "The in-law is death," meaning that the in-law must enter upon his brother's wife just as death must befall every living being. Yes, is this concept correct? What is the meaning of "the in-law is death"?
It means flee from him as you flee from death. The in-law is more dangerous than a stranger, because the in-law enters his relative's house without him being aware of it, and he does not find it objectionable or strange. Unlike a stranger; when a stranger enters a man's house, people must ask about it, and the owner of the house must be informed. But if his brother enters, it is a problem. So the meaning of the saying of the Prophet (peace and blessings be upon him), "The in-law is death," is: flee from him as you flee from death, or beware of him as you beware of death.

The questioner : Well, Shaykh, the man treating the woman, the man treating the woman.

The Shaykh : And the man treating the woman is the same in medicine; if it is needed, there is no blame, but there must be no seclusion. It is necessary that