are you addicted to any of the 4 Cs?

On a serious note, the C≡N group actually can be. Nitriles (organic cyanides) are involved in several medications, such as arguably the best drug we have right now for treating breast cancer, due to its rigidity and ability to avoid metabolisation by the body. Nitriles can also be found across many plants.

Inorganic cyanides however, including hydrogen cyanide gas, potassium cyanide and sodium cyanide salts (which I presume you meant by cyanide in the comment before since these are involved in human poisoning), tend to produce the cyanide ion very easily which bonds to the iron in your blood and prevents cellular respiration, resulting in no production of ATP - the body's energy resource - and hence, no energy is provided to the heart or central nervous system causing death between one and ten minutes... Not nice.