Crack cocaine is a highly potent, rapidly-acting central nervous system stimulant. When smoked, the drug delivers an intense, short-lived rush of euphoria by flooding the brain with neurotransmitters. Users frequently report a disturbing physical side effect: an intense sensation of itching or feeling as though something is crawling beneath the skin. This sensory disturbance is a common complaint, prompting a closer look at how this stimulant alters the body’s perception of touch.
Understanding Formication
The sensation of feeling things crawling on or under the skin is a well-documented side effect of stimulant use. This condition has a precise medical term: formication, a type of tactile hallucination. The feeling is not merely an itch but a deeply unsettling, phantom sensation that mimics the movement of insects, often described colloquially as “cocaine bugs” or “coke bugs.”
This hallucination leads many to scratch, pick, or tear at their skin in an attempt to remove the perceived infestation. The term formication is derived from the Latin word formica, meaning “ant,” directly referencing the crawling, prickling feeling. First documented in chronic cocaine users in 1889, this symptom is typically dose-dependent, becoming more pronounced with higher doses and extended use. The physical consequences of this delusion are often visible, resulting in lesions, scabs, and open sores known as excoriations on easily reachable areas of the body.
The Biological Mechanisms Behind the Sensation
The primary cause of the crawling hallucination is rooted in the drug’s profound impact on the central nervous system (CNS). Crack cocaine acts by blocking the reuptake of neurotransmitters, particularly dopamine and norepinephrine, leading to a massive buildup in the synaptic space. This rapid, extreme overstimulation of the CNS can trigger a state of drug-induced psychosis.
Overwhelmed by this chemical surge, the brain’s sensory neurons begin to misfire and generate erroneous signals. These distorted impulses are then interpreted by the brain as physical stimuli. This neurological misinterpretation is the direct cause of the formication, creating a tactile deception where no physical cause exists.
A separate factor contributing to skin discomfort involves the drug’s peripheral effects on circulation. Cocaine is a strong vasoconstrictor. This constriction reduces blood flow and oxygen delivery (hypoxia) to the skin and peripheral tissues.
This impaired circulation can lead to generalized skin dryness, irritation, and conditions like dermatitis. Metabolites from cocaine can also trigger a histamine release, which further contributes to itching and hives. While this peripheral irritation is distinct from the hallucinatory crawling, it adds to the user’s overall skin distress and urge to scratch.
Other Immediate Physical Effects
Beyond the sensory hallucinations, crack cocaine initiates physiological changes shortly after consumption. One immediate effect is an increase in heart rate, known as tachycardia. This is coupled with a sharp elevation in blood pressure, or hypertension, which places strain on the cardiovascular system.
The drug’s stimulation affects temperature regulation, frequently leading to hyperthermia, or an abnormally increased body temperature. This rise in temperature can be dangerous, especially in high-dose scenarios. Visible signs of CNS engagement include mydriasis, the noticeable dilation of the pupils.