Excessive sweating is a common and often distressing physical symptom associated with chronic heavy alcohol use, formally described as alcoholic hyperhidrosis. This condition manifests in different ways, from sweating during active drinking to intense, drenching sweats during periods of abstinence. The reasons for this excessive perspiration involve the direct effects of ethanol, the body’s rebound response to withdrawal, and long-term changes to the central nervous system.
Sweating During Active Alcohol Consumption
Drinking alcohol triggers vasodilation, where blood vessels near the skin surface widen. This increased blood flow causes a feeling of warmth or a flushed appearance, especially on the face and chest. The body interprets this surface warmth as a rise in core temperature, activating its natural cooling mechanism: sweating. This process leads to a drop in the body’s core temperature as heat is lost through evaporation.
The metabolic effort required to break down alcohol also contributes to heat generation. The liver processes ethanol, converting it first into acetaldehyde and then into less toxic substances. This intensive chemical conversion is a thermogenic process that raises the internal temperature slightly. This prompts the body to sweat further in an attempt to maintain homeostasis.
Sympathetic Nervous System Hyperactivity During Withdrawal
The most severe and profuse sweating occurs when a person who is physically dependent on alcohol stops or significantly reduces their intake. Chronic alcohol use is a depressant that continuously suppresses the central nervous system (CNS). To counteract this dampening effect, the brain adapts by increasing the activity of excitatory neurotransmitters to maintain balance.
When alcohol is suddenly removed, this artificial suppression is lifted, and the over-sensitized CNS rebounds into a state of hyperactivity. This rebound involves the sympathetic branch of the autonomic nervous system, which controls the “fight-or-flight” response and involuntary functions like perspiration. The system is flooded with stimulating stress hormones, such as adrenaline and noradrenaline, which drive up heart rate, blood pressure, and body temperature. This intense internal stimulation directly causes severe hyperhidrosis, often described as drenching night sweats.
These withdrawal symptoms typically begin within 6 to 24 hours after the last drink and peak in intensity between 24 and 72 hours. The severity of this autonomic hyperactivity reflects the degree of physical dependence. The body is struggling to regain its normal balance without the depressant effects of ethanol.
Long-Term Disruption of Core Body Temperature
Beyond the immediate effects of intoxication and acute withdrawal, chronic alcohol abuse can lead to persistent changes in temperature regulation. The hypothalamus, a region in the brain, acts as the body’s thermostat, regulating core functions like body temperature. Prolonged exposure to high levels of alcohol can damage or dysregulate this control center.
This chronic disruption leads to a miscalibration of the internal thermostat, meaning the sweating mechanism may be triggered inappropriately or excessively. The body’s set point for temperature may be altered, causing exaggerated sweating responses to normal stimuli, even outside of acute withdrawal. This long-term dysregulation manifests as persistent hyperhidrosis.
When Excessive Sweating Is a Medical Concern
While mild sweating is common during alcohol withdrawal, its presence alongside other symptoms can signal a medical emergency. Profuse sweating is a hallmark of severe Alcohol Withdrawal Syndrome (AWS) and indicates significant autonomic instability. If sweating is accompanied by a high fever, confusion, severe agitation, or hallucinations, immediate medical intervention is required.
The most severe manifestation is delirium tremens (DTs), which typically occurs 48 to 72 hours after the last drink. DTs is characterized by heavy sweating, rapid heart rate, high blood pressure, and profound disorientation. The combination of profuse sweating and elevated body temperature indicates a life-threatening condition that carries a risk of seizures and death if left untreated.