Q: Can a female doctor treat male patients?
A. A non-mahram female may not see any part of the body of a male and vice versa. Likewise, close communication between non-mahrams of the opposite sex is not allowed in Islam. On this basis, it will not be permissible for a female doctor to treat male patients, just as under normal circumstances it is not permissible for a male doctor to treat a non-mahram female.
However, cases of emergency are excluded from this prohibition. For example, a male has been seriously injured in an accident and needs urgent medical attention and no male doctor is available, or a man suffers a sudden collapse of organs and requires immediate attention. Under these cases it will be permissible for a female doctor to treat the male patient. Another example of emergency is when the female doctor is the only one who provides treatment in a certain specialist field, such as a neuro-surgeon or heart specialist etc. and surgery needs to be carried out. In these extreme cases Shari'ah lifts the restriction for both males and females.
The same principle as above will apply to a male doctor treating female patients.
And Allah Ta’aala knows best.
Mufti Siraj Desai