When anyone among you eats, he should eat with the right hand and when he drinks, he should drink with the right hand. (Muslim: No. 2020) http://forums.understanding-islam.com
Al-Shawkaani (may Allah have mercy on him) said in Nayl al-Awtaar (8/183): His words “No one among you should eat with his left hand” signify that it is not allowed to eat or drink with the left hand, and this prohibition has the sense of being haraam, as is established in usool; it should not be interpreted as meaning that it is no more than makrooh unless there is some indication to that effect in the context. Al-Nawawi said: This applies if there is no excuse. If there is an excuse which means that a person is unable to eat or drink with his right hand, because of sickness or injury and so on, then it is not disliked to use the left hand. End quote.