That would depend upon how much water and food the person has with him/her. If it is in the middle of the summer in a hot desert you will need much more water than in a cool desert or in the winter. Generally, it is recommended that you have a minimum of one gallon per person per day. Even more would be safer. However, that is a lot of weight. Without sufficient water in a hot desert a person would start to experience severe health issues within a day and would expire within 2 or 3 days.
Food is generally not a big issue as a person can go for weeks without food. However, the person would have little energy to move.
As long as you have sufficient water and food and shelter, you can stay indefinitely.
just until night time
As long as a person has proper clothing and sufficient water, a person can remain outside in a desert biome indefinitely.
BoZo
Contrast dye is used to enhance the quality of an x-ray. Contrast dye does not stay in the human body for very long, but it can stay for up to several hours.
Long roots of desert plants penetrate deep in the soil in search of capillary water and absorb it for the plant's survival
5 minutes
I don't think desert-adapted animals have long tails. They generally try to stay as small as possible to avoid massive heat build-up.
9 months
until you stop breathing
Animal adaptations
She was constantly leaving and coming to the human wold throughout the series.