Endocarditis is an inflammation of the valves and/or smooth tissue (endocardium) lining in the heart.

Many of the wide range of organisms which cause endocarditis in injecting drug users can be present on the skin or in the mouths of injectors, which is a good reason for making the injecting process as hygienic as possible. If untreated, endocarditis prevents the heart valves operating properly and leads to heart failure.

Several factors have been identified as possible predisposing factors for the development of endocarditis in injecting drug users:

• A pre-existing heart condition
• Poor hygiene when injecting
• Failure to wash hands prior to injecting
• Failure to clean the injecting site before injecting
• Licking or blowing on the needle tip
• Licking the injection site
•  Injecting crushed tablets or other particulate matter
• Injecting cocaine.