The experience of sweating when cold feels counterintuitive because the body typically sweats to release excess heat. This phenomenon is part of thermoregulation, the complex process by which the body maintains a stable internal temperature. The body’s control system constantly balances heat production and heat loss to keep the core temperature steady. When cold is perceived, a powerful nervous system response is triggered that can sometimes include an inappropriate activation of the sweat glands.
The Underlying Physiological Response
The primary mechanism for dealing with cold is governed by the sympathetic nervous system, the “fight or flight” branch of the autonomic nervous system. When cold receptors in the skin are stimulated, this system immediately initiates vasoconstriction, which narrows the blood vessels near the skin’s surface. This reflex reduces blood flow to the extremities, insulating the body and conserving heat near the vital organs.
Sweating (the sudomotor response) is also controlled by this same sympathetic nervous system pathway. The signal to constrict blood vessels and the signal to activate sweat glands can sometimes overlap or become disproportionately activated under stress. This co-activation leads to the paradoxical feeling of being cold and clammy at the same time.
The type of sweat matters, as the body possesses two main types of sweat glands. Eccrine glands produce the watery sweat used for evaporative cooling when the body is hot. Apocrine glands, found mainly in the armpits and groin, are activated by emotional stress, producing a thicker, protein-rich sweat. The “cold sweat” associated with fear or pain is primarily this apocrine-driven stress response, which feels cold on the skin, especially when peripheral blood vessels are constricted.
Another physiological factor is the body’s attempt to generate internal heat through shivering. Shivering involves rapid, involuntary muscle contractions that are highly effective at producing heat. This intense metabolic activity can sometimes temporarily raise the core body temperature slightly above the ideal set point. If the shivering overshoots the target, the central thermostat may briefly activate the eccrine sweat glands to initiate a minor cooling response, resulting in perspiration despite the cold.
Common External and Situational Triggers
Situational factors that increase core temperature or activate the stress response can override the cold signals from the skin. A common external trigger is over-insulation. Wearing too many layers of clothing in a cold environment traps heat and moisture close to the skin.
This trapped heat quickly raises the skin temperature, signaling the body to start sweating to prevent overheating, even if the surrounding air is cold. Since the sweat cannot evaporate effectively through thick layers, it leads to a saturated feeling that quickly turns cold as the moisture cools down.
Sweating may also occur during the post-activity cooldown phase after vigorous exercise in cold weather. While exercising, muscles produce significant heat that continues to radiate even after movement stops. The body must continue to shed this heat via eccrine sweating.
Emotional stress and anxiety can also manifest as cold sweating, independent of thermoregulation. Psychological stress triggers the fight-or-flight response, which stimulates the apocrine sweat glands. This results in the clammy, non-thermoregulatory cold sweat.
When Cold Sweating Indicates a Health Issue
While most cold sweating instances are benign physiological or situational responses, persistent or severe episodes can signal an underlying health condition. One condition is hyperhidrosis, which involves chronic, excessive sweating disproportionate to the body’s need for cooling. People with hyperhidrosis have overactive sweat glands that may be triggered inappropriately by minor stimuli, including cold temperature fluctuations.
Hypoglycemia, or low blood sugar, is another common medical cause of cold sweats. When blood glucose levels drop too low, the body releases stress hormones like adrenaline to signal the liver to produce more sugar. This rush of hormones simultaneously triggers the sympathetic response, causing the characteristic cold, clammy sweat often accompanied by shakiness and dizziness.
Thyroid dysfunction, specifically hyperthyroidism (an overactive thyroid gland), can disrupt the body’s metabolic rate. Excess thyroid hormone acts like an internal thermostat turned too high, increasing metabolism and heat production. This heightened internal temperature leads to a generalized, inappropriate sweating response regardless of external weather.
If cold sweating is a chronic, debilitating problem, or a sudden event accompanied by concerning symptoms, medical evaluation is necessary. Seek immediate medical attention if cold sweats are accompanied by chest pain, difficulty breathing, sudden severe dizziness, or fainting. For less urgent concerns, such as frequent, unexplained cold sweats or those accompanied by rapid weight loss, consult a physician to rule out hyperhidrosis or thyroid issues.