If a person is unconscious but is breathing and has no other life-threatening conditions (like spinal injury), they should be placed in the recovery position. Putting someone in the recovery position will ensure their airway remains clear and open. It also ensures that any vomit or fluid will not cause them to choke.
- First aid for someone who’s unconscious and breathing @ British Red Cross
Excerpt: Check breathing by tilting their head backwards and looking and feeling for breaths. When a person is unconscious their muscles relax and their tongue can block their airway so they can no longer breathe. Tilting their head back opens the airway by pulling the tongue forward. Looking at their chest to see if it’s moving, and feeling for breaths on your cheek, will help you tell if they’re breathing or not.