What cocaine does to your body and brain

Normally, our brain cells cycle and reuse hormones like serotonin and dopamine, which play critical roles in how we experience desire, motivation, pleasure, and reward. After they're released by brain cells to send out their signal, they're taken up again by special receptors on that cell. Cocaine blocks those receptors, effectively shutting off this normal cycling process. The result? A glut of the hormones that key our feelings of desire, behavior reinforcement, and pleasure (AKA a "high").

Increased levels of both dopamine and serotonin can result in dilated pupils, and cocaine boosts both.

Cocaine is thought to boost levels of dopamine — a hormone which plays a key role in reinforcing a behavior — in several brain circuits, including one that's involved in pleasure and another that's involved in movement. This is one of the reasons some users may feel more energized, talkative, or alert, studies suggest.

Studies suggest a link between cocaine use and psychosis, when someone loses touch with reality. Symptoms of psychosis include agitation, anxiety, paranoia, and hallucinations. Still, we can't say for certain what role the drug plays in these symptoms. While some studies suggest that people who experience psychosis while using cocaine are more likely to experience it later (even when they're not using), others suggest that using cocaine can worsen underlying mental illnesses like anxiety.

The part of the brain cocaine affects includes key memory centers that help us recall where the source of pleasure came from. When we experience a cocaine high, these brain areas form memories of our pleasurable experience and the places or people that were involved in our experience of getting the drug. This is why, in some people, going back to the original spot where you used cocaine — or simply seeing pictures of someone else using — might trigger a renewed desire to use.

Cocaine stimulates the sympathetic nervous system, which regulates our "fight or flight" response. This also tightens up the vessels that ferry blood through our organs and tissues.

Since your vessels are narrowed, your heart has to work harder to pump blood to the rest of your body.

Diminished appetite is one of the most frequently reported effects of using cocaine, which is why frequent users may lose weight or be malnourished. While this has so far been mainly anecdotal in people, it's also been observed in rat studies.

A 2013 study found that cocaine could mess with your body's ability to store fat. The researchers observed 65 Britons, roughly half of whom had been addicted to cocaine for more than a decade (the other half had never used the drug).

They came away with two surprising findings: 1) The addicts tended to eat more (and even have different protein levels which should have made them put on weight) than those who'd never used, and 2) They also tended to have less body fat than the never-users. Their conclusion? Cocaine seems to cause fundamental changes to our metabolism.

A 2012 study presented at a meeting of the American Heart Association found that even in young people who only reported using cocaine "socially," the drug could significantly raise the risk of heart attack. "It's the perfect heart attack drug," the study's lead author, University of Sydney professor of medicine Gemma Figtree, said in a press release.

Cocaine constricts blood flow to the septum, the part of the nose which separates your right and left airways and divides your nostrils. Repeated use can cause holes in the area, which cannot heal without treatment.

Some of cocaine's effects can fluctuate depending on the method of use. Regularly snorting it, the National Institute on Drug Abuse notes, can cause: a loss of the sense of smell, nosebleeds, problems swallowing, hoarseness, and a runny nose.

Smoking crack cocaine has been linked with numerous lung issues, including injuries to the airways, asthma, a range of symptoms referred to as "crack lung," interstitial lung disease, pneumonia, bronchiolitis, pulmonary hypertension, emphysema, infections, and tumors.