Alcohol and Body Temperature

Does alcohol warm you?

Alcohol dilates arteries and increases the blood flow through your skin, hands, fingers and toes thus giving you a feeling of warmth soon after starting drinking ^[1,2,3]. However, alcohol does not produce significantly more heat in your body than other macronutrents: somewhat less than proteins and more than carbohydrates and fats ^[4,5].

Drinking up to about 5 drinks (70 grams of pure alcohol) in one session in a temperate environment probably does not significantly affect the body core temperature ^[6,7].

Alcohol and Hypothermia

Hypothermia (a drop of the body temperature below 95 °F or 35 °C) in chronic alcoholics is common and so is death from hypothermia ^[8,9,10]. Alcohol-related causes of hypothermia include:

• Decreased perception and sensation of cold. Intoxicated people tend to be less aware of cold. Beside that, alcohol intoxication resulting in blood alcohol concentrations (BACs) above 0.3 g/100 blood acts as an anesthetic.
• A heavily drinking person exposed to cold who has been not eaten for a day or more may develop hypoglycemia, which may result in decreased shivering and therefore decreased heat production and hypothermia ^[11].
• Paradoxical undressing. A drinker who starts to feel warm due to increased skin blood flow often partly undresses despite a low ambient temperature ^[7].
• Sleepiness. An intoxicated person who has lain or fallen down may quickly fall asleep and not wake up despite the cold ambient.
• Increased loss of heat through the skin due to dilated skin arteries. After drinking alcohol, the skin arteries widen, which results in increased blood flow through the skin. Despite this, in some studies, thee was no significant difference in the mean body core (rectal) or the skin temperature between alcohol intoxicated (BAC around 0.1 g/100 mL blood) and non-intoxicated individuals exposed to air or water as cold as 50 °F [10 °C] for 20-60 minutes ^[7,12,13,14].
• In severely intoxicated chronic alcoholics with a transient brain damage called Wernicke encephalopathy, hypothermia may develop due to impaired thermoregulation ^[15].
• According to one theory, alcohol causes a drop of the set-point of the thermoregulatory center in the brain thus making a person who was drinking to feel more comfortable in a colder environment than when not drinking ^[6,16].

It seems alcohol directly contributes to hypothermia only when it also causes hypoglycemia, which can occur due to a combination of drinking and fasting or drinking and exercise. A typical person at increased risk of hypothermia is a skinny homeless man, a chronic alcoholic on a poor diet, who undresses after starting to feel warm and lies or falls down outside in cold.

Can drinking alcohol prevent frostbite?

Doctors usually advise against drinking alcohol in order to prevent hypothermia or frostbite, because alcohol may, in certain circumstances (hypoglycemia), aggravate hypothermia ^[17].

Alcohol drinking results in widening of the arteries and thus increased blood flow in the skin, hands, fingers and toes which warms them ^[7,18]. Smoking prevents alcohol-induced dilation of arteries in the fingers ^[19]. In one study the finger skin temperature increased 30 minutes after drinking alcohol and was still increased at 60 minutes ^[2]. In another study, after about 4 drinks the skin temperature in fingers increased by 2.4 °C and in toes by 3.4 °C in average ^[1]. According to Granberg, P.O., from Karolinska Hospital, Stockholm, Sweden, “alcohol may have some positive properties in freezing alcohol injuries” ^[10], but there are no known studies that would confirm that.

Alcohol and Hyperthermia

Theoretically, if you drink large amounts of alcohol in a hot environment, you may develop hyperthermia (rise of the body temperature above 101.3 °F or 38.5 °C), because alcohol can impair thermoregulation ^[6,20,21]. However, in one study, in participants who have drunk about 6 standard drinks and were then exercising for 1 hour at 45% intensity at 95 °F [35 °C] their mean body core or skin temperature did not increase significantly more than when they were exercising without alcohol ^[25]. In another study, in participants who had 3 drinks and then underwent immersion in 104 °F [40 °C] water for 21 minutes, their body core temperature was not significantly higher than when they were immersed in the same water without prior drinking ^[22].

Hyperthermia may develop as a part of delirium tremens after alcohol withdrawal ^[23].

Drinking alcohol may make heatstroke worse ^[24].