Short answer
Yes. Losing consciousness breaks wudu, whether by fainting, a seizure, general anaesthesia, heavy sedation or being drunk, and the four schools agree. A local anaesthetic, such as at the dentist, does not break wudu, because you stay awake and aware.
Loss of reason through fainting, madness, intoxication or anything that removes awareness breaks wudu in every posture, even for a short time. Intoxication means being affected so that one's walk becomes unsteady. Local anaesthesia that leaves awareness does not break wudu.
The four schools agree on this.
Explanation
Sleep breaks wudu (ablution) in certain postures because a sleeper cannot tell whether wind has passed. Fainting and anaesthesia go further: the person loses awareness completely, in any posture, so all four schools count them as breakers. In his final illness the Prophet ﷺ fainted while waiting to lead the prayer, and each time he came round he asked for water to wash before trying to get up again.
Cases that break wudu:
- fainting or blacking out, even for a few seconds
- an epileptic seizure with loss of consciousness
- general anaesthesia for surgery
- sedation that puts you to sleep, such as for some scans or a colonoscopy
- being drunk or high to the point of losing control
Cases that do not:
- a local anaesthetic at the dentist or for stitches
- feeling dizzy or light-headed without losing awareness
- painkillers or medicines that leave you clear-headed
After surgery, make wudu as soon as you are able. If you cannot wash some limbs because of dressings, wipe over them: see wudu with a bandage. If you cannot use water at all, make tayammum. If you were unconscious for more than a day and night (six prayers), the Hanafi school excuses you from making up the missed prayers; for less, make them up: see the qada calculator.
For the full list of breakers, see what breaks wudu.
The evidence
Sahih al-Bukhari 687
Sahih... ضعوا لي ماء في المخضب ...
"Put some water in the tub for me."
In his last illness the Prophet ﷺ bathed again each time he came round from fainting, before trying to go out to the prayer.
Where the ruling is recorded
- al-Hidaya, Kitab al-Taharat, chapter on what breaks wudu. Fainting, madness and intoxication break wudu in every state.
- Nur al-Idah with Maraqi al-Falah, Kitab al-Taharah, chapter on what breaks wudu. Loss of reason by fainting or intoxication.
- al-Mughni (Ibn Qudama), Kitab al-Taharah, chapter on what breaks wudu. Scholars agree that loss of reason breaks wudu.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.