Praise be to Allah.
The nebuliser is a device that transmits liquid medicine directly to the lungs by means of inhalation, after turning it into a mist that is inhaled via the mouth or nose.
It is used to treat seasonal chest allergies, asthma attacks and other respiratory disorders.
Inhaling the mist breaks the fast, Therefore it is not permissible for one who is fasting to use this device during the day in Ramadan, except in cases of necessity, and if he uses it he breaks the fast.
See also the answer to question no. 78459.
It is not permissible to issue fatwas on the basis of speculation when one is not certain. This doctor should have verified the facts before saying that using this device does not break the fast, or she should have told the patient to ask the scholars.
Hence what the doctor must do is repent to Allah, may He be exalted, and inform the patient of her error. Based on what you mention, she did well to contact the patient, then send a message to him. She does not have to offer any expiation or do anything more than what we have mentioned above, and the patient, if he used the device, does not have to do anything other than making up the fast that was broken.
Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) was asked: If someone gives a fatwa to someone else, then after a while he checks the views of the scholars on this issue, and realises that his fatwa was wrong, what should he do? Is there any sin on him? We hope that you can advise us about this.
He (may Allah have mercy on him) replied: If his first fatwa was based on his own ijtihad (efforts to work out the correct ruling), and he was qualified to engage in ijtihad, then after researching and discussing the matter it became clear to him that his first ijtihad was wrong, then he does not have to do anything.
The major scholars used to do that. You will find that one of them had several views regarding a single issue.
But if his first fatwa was not based on knowledge or on ijtihad (making an effort to work it out), and was rather based on speculation, some kinds of speculation constitute sin, so it was haraam for him in the first place to issue a fatwa based on mere speculation or guessing, because if he did that, then he has spoken about Allah without knowledge, and speaking about Allah without knowledge is one of the gravest of sins, because Allah, may He exalted, says (interpretation of the meaning): “Say, ‘My Lord has only forbidden immoralities - what is apparent of them and what is concealed - and sin, and oppression without right, and that you associate with Allah that for which He has not sent down authority, and that you say about Allah that which you do not know’” [al-A ‘raaf 7:33].
So he has to look for the person who asked him that question, so that he can tell him that his fatwa was wrong. If he does that, then I hope that Allah will turn in mercy to him.
The issue of giving fatwas without knowledge is a very serious matter, because it is not only the one who asks the question who may be led astray by that; rather the one who asked the question may spread it to other people, and thus many people may be led astray by it, and this is very wrong.
End quote from Fataawa Noor ‘ala ad-Darb.
If the doctor prescribed this device for someone who needs it during the day, but did not tell him whether or not it breaks the fast, then what appears to be the case is that there is no sin on her, because he has no choice but to break the fast due to his sickness, so he is excused. The onus is on the patient to ask the scholars whether using this device breaks the fast or not, and if he fails to do that then the shortcoming is on his part.
If she prescribed it to someone who can do without it during the day, and did not point that out to him, then in that case she is sinning if she knew that he would use it during the day, and did not point it out to him, because she is the one who caused his fast to be spoiled with no excuse.
But if she did not know whether the patient would use the device during the day or at night, then there is no sin on her.
She and other doctors should learn about the rulings on acts of worship that have to do with their specialties, such as purification, prayer and fasting, lest they spoil the patient’s acts of worship without realising. If they are confused about something, then they should instruct the patient to ask the scholars about the ruling on it.
And Allah knows best.