Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states: “If one can avoid mouth wash which contains alcohol it is preferred to do so.
But if you find you have no choice but to use it, then you may use it provided you make sure no drop of it enters your system. Wash your mouth thoroughly with water immediately after using them. It should be fine.”
Moreover, Dr. Muzammil H. Siddiqi, former President of the Islamic Society of North America states: “According to the Qur’an and Sunnah, it is haram to drink alcohol or alcoholic beverages. Even a small amount of alcohol is haram and it must be avoided. However, jurists have differed on the najasah (physical impurity) of alcohol. Some of them consider it najis (impure), meaning that if it touches the body and clothes then it must be washed. There are others who do not consider it najis.
As far as toothpaste and mouthwash that contain alcohol are concerned, it is better to avoid them, because they go inside the mouth.”