He becomes tired. The drug only breaks the body down further. Now strange distortions of bodily form occur as the belly starts to protrude due to expanding intestines whose insides are growing thicker with sticky sludge. Molds exist to some small extent naturally in the body and in the environment. The molds' toxic waste products, which include alcohol, poison the body and can create fatigue and many other difficulties.
Parasites add to the problem, robbing the body of more energy.
Less and less food can be absorbed and the pressure of the intestines on the spine and internal organs increase the body's slide into poor health. Soon the body cannot repair itself and damage becomes chronic. Amazingly and thankfully, this is a preventable plague. And usually the effects are reversible if caught early enough or if one works at it hard enough. The first thing that should be done is to replace the helpful bacteria immediately after any use of antibiotics.