Islam never takes marriage and divorce lightly. The words of divorce are serious, and one should say them with the full understanding of the consequences.
If a sick man divorces his wife while not in full control of his senses due to drugs taken under doctor’s orders, the divorce is invalid. The lady who has sent the question said that her husband was anesthetized under doctor’s orders when he divorced her; in this case the divorce is null and void.
In the Hashiyah of Ibn `Abidin (one of the Hanafi jurists), it says that if a man was under anesthesia or under the influence of drugs (opium) and divorces his wife, the divorce is valid if he was taking these drugs for non-medical reasons; if, on the other hand, he was taking these drugs under the orders of a physician, the divorce in this case will be null. Correspondingly, Fath Al-Qadir (a book of jurisprudence by Ibn Humam) was explicit in forbidding the use of drugs for non-medical purposes. The principle is that whatever in a large quantity makes the person lose control of his senses is forbidden in the absolute.
If the amount of drugs taken is limited and not for a medical reason, and as a result the person loses his senses, the divorce will be valid, since the use of drugs is forbidden. But if the drugs are taken under medical care the divorce will be null and void.
Al-Mirdawi Al-Hanbali (may Allah have mercy on his soul) points out in his books Al-Insaf and in Al-Jami` Al-Kabir: If the temporary loss of senses is due to anesthesia taken under medical care, the ruling applied will be that of the ruling for insanity (therefore the divorce is invalid). But if the temporary loss of senses is due to the intake of drugs for non-medical reasons, the ruling applied will be that of the ruling for drunkenness (hence the divorce is valid).
Al-Jaziri’s interpretation of the laws according to the four schools of Islamic jurisprudence is this: If drugs were taken for a non-medical reason and, consequently, the person loses his senses and divorces his wife, the divorce is considered valid. But if these drugs were taken under medical supervision for the sake of treatment and the person loses his judgment and divorces his wife, the divorce is invalid.
The Indian Council of Fiqh adds:
If a person is under the influence of drugs taken for medical reason, and there was no alternative medicine to alleviate the pain and preserve his life other than this forbidden medical procedure, and while in this condition the man divorces his wife, the divorce will be null and void.