For most treks, previous trekking experience is not mandatory as long as you are willing to train beforehand and prepare for a real physical challenge. However, for more demanding routes such as the Everest Three Pass Trek, Upper Dolpo, Dhaulagiri Circuit, or Nar Phu Valley, we strongly recommend prior trekking experience.
These treks involve extreme altitudes, remote areas with limited facilities, long and strenuous days, and sometimes technical passes, so preparation and experience are essential for safety and enjoyment.