How are enzymes inhibited?

There are two types of enzyme inhibition: competitive and non-competitive. 

Competitive inhibition:
This occurs when an enzyme's active site is filled by an inhibitor. The inhibitor will have a complementary shape to the enzyme's active site and thus be able to bind to the active site and stop enzyme-substrate complexes from being formed. This inhibition is usually temporary. 

Non-Competitive Inhibition: 
This occurs when an inhibitor binds to a site on the enzyme that is not the active site. When this happens, the enzyme's active site changes shape, meaning the substrate is no longer complementary to the active site. Enzyme-substrate complexes can no longer be formed, resulting in a usually permanent inhibition.