Cocaine is a highly addictive drug, a fact which often leads to long-term use, impacting every organ in the body from the brain to the skin. How the drug is ingested and abused is one of the biggest factors in how the skin will be impacted and what sort of lesions will appear.
Most injected drugs leave sores or "track marks" indicating the habitual use of the drug. Injecting cocaine enables the user to access the effects of the drug faster. Injections will rapidly destroy the skin tissues, and can cause open sores, or skin ulcers. In addition to open sores--or even as a result of the open sores--needles can cause skin infections known as cellulitis or abscesses. Some cocaine users have been known to leave the needle in the skin, most likely unknowingly.
When cocaine is smoked with deep inhalations and then held in, this can result in a lung collapsing. When this happens, the smoker will experience a sharp chest pain, especially when trying to take a deep breath, and will have a tough time swallowing; it will also feel like someone put Rice Krispies under the skin of the neck when touched.
Formication is a hallucinatory disorder which comes from long-term use regardless of form of ingestion. It is when the long-term user believes there are bugs crawling under his skin. As a result, the user can repeatedly scratch at his skin, causing lesions, bleeding and infection. The long-term user also has a much weaker immune system and is unable to heal from these self-inflicted wounds as quickly as he would otherwise.
Dermatillomania is another disorder caused by long-term cocaine use, regardless of the method of ingestion. Cocaine can cause paranoia and obsessive behaviors, leading to this pathological skin picking disorder. The user may pick at freckles, moles and other skin defects to the point of creating open sores. As with needle injections, open sores in a long-term user can get infected and take longer to heal due to the compromised immune system. Users who suffer from this disorder are known to use anything they can to pick at their skin, including their fingers, teeth, blades or other sharp objects.