A carcinogen is a cancer causing substance.
Carcinogen
Antigen is the medical term meaning foreign substance.
Keratin
antibiotic
Soporific is the medical and common term meaning pertaining to something that produces sleep.
"Placebo". Alternatively, "homeopathy".
It is called bilirubin.
Allergen
Bioavailability
A pediculocide kills lice. It is a class of insecticides.
The substance injected during an angiography is called radionuclide.
Anacusis is the medical term meaning complete deafness.
Syncope is the medical term meaning fainting.