Most inhalants are common household products that give off mind-altering chemical fumes when sniffed.  Common inhalants include:  paint thinner, fingernail polish remover, glues, gasoline, cigarette lighter fluid, nitrous oxide, and fluorinated hydrocarbons found in aerosols.  

The chemical structures of these inhalants are diverse which makes it difficult to make generalizations about their effects.  They can change brain chemistry and permanent damage to the brain and central nervous system.  Inhalant users are at risk for Sudden Sniffing Death (SSD), which can occur when the inhaled fumes take the place of oxygen in the lungs and central nervous system.  Basically, the inhalant user suffocates.

Because inhalants enter the bloodstream quickly and are distributed throughout the brain and body, they have direct effects on the central and peripheral nervous systems.  Brain-imaging techniques (magnetic resonance imaging or MRI) have shown marked structural changes in the brains of chronic inhaling abusers.

These include a reduction in size of parts of the brain including the cerebral cortex, cerebellum and brainstem.  These changes cause neurological and behavioral symptoms such as cognitive and movement difficulties. 

When they enter the body, inhalants are particularly attracted to fatty tissues such as myelin, which insulates and protects axons and helps speed up nerve conduction.  Inhalant can destroy myelin which interferes with the flow of messages from one nerve to another.  When myelin is destroyed, the axons themselves can also degenerate.