You must also bring water purifying tablets and a water bottle. The tap water in Everest region is excellent but we recommend you to use the purifying tablet. If you get stomach upset, drink only boiled water.
If your sickness gets worst, you must get to a hospital in Lukla. Pasang Lhamu Nicole-Nicky Hospital in Lukla has excellent facilities and will take good care of you. You can also fly back to Kathmandu from Lukla.
Sources : RCDP Nepal Volunteer