It depends on the quality of the tequila. The cheaper the tequila, the poorer the quality. Poor quality tequila will cause immediate liver pain. It will stress the liver and the liver will not function properly. This will affect the kidneys since the liver and the kidneys function as a waste processing system and toxicity regulator.
The Mexican custom of covering the rim of the glass of a shot of tequila with a lot of salt neutralizes the acidity of the tequila besides just for taste.
Tequila without the salt is acidic to the liver and the kidneys, and this increases blood acidity in the kidneys, thus damaging the kidneys severely.