Part of the blood containing cocaine molecules which leaves the heart via the aorta is pumped to the brain. When you inject cocaine, you begin perceiving the effects 15 to 30 seconds later.
If the cocaine is injected directly into a vein, all of the cocaine molecules arrive in the brain at approximately the same time. This causes a rapid peak concentration of cocaine in the brain.
You experience a sudden, intense effect called a ‘rush’ or ‘buzz’. The rush that you get from injecting cocaine is stronger than the high obtained from any other way of taking cocaine.