If you feel like you're always cold, it may be because of a condition known as cold intolerance. Cold intolerance is not an illness but simply an abnormal sensitivity to cold environments or cold temperatures.
Cold intolerance may be caused by a problem with your metabolism (the conversion of calories to energy) or by nervous system disorders that alter your perception of cold. Conditions like hypothyroidism, poor circulation, or anemia can also contribute to cold sensitivity. Even being thin can make you extra sensitive to cold.
This article looks at 15 different causes of cold intolerance, including why they occur and what you can do.
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Symptoms of Cold Intolerance
Cold intolerance, also known as cold sensitivity or hypersensitivity, is an elusive condition in which you have an exaggerated reaction to cold, causing discomfort and/or the avoidance of cold.
Cold intolerance is a subjective response that is irrespective of the ambient temperature. The response is largely physiological (related to the body), although it may also have psychological components (related to the mind).
There is much variation in the sensitivity to cold that different people experience. Some may only shiver and put their hands in their pockets in response to the cold. Others may require layers of clothes to keep warm.
In addition to an abnormal response to cold, symptoms of cold intolerance may also cause:
- Numbness
- Stiffness
- Pain or burning sensations
- Weakness
- Swelling of the skin
- Skin color changes
- Sensitivity to touching cold objects
Cold Intolerance vs. Hypothermia
Cold intolerance is not the same thing as hypothermia (a reduction in body temperature when it loses more heat than it can generate). Cold intolerance occurs at temperatures that are otherwise tolerable to others in that environment.
Causes of Cold Intolerance
There is no universally accepted definition of cold intolerance since the underlying causes are so varied, and not everyone with a medical condition that can cause cold intolerance experiences it. In fact, cold intolerance is thought to be multifactorial, meaning that more than one cause is involved. These can be broadly categorized as:
- Hormonal problems that alter metabolism and thermal regulation
- Blood circulation problems that alter body temperature
- Nervous system disorders that alter the perception of cold
With that said, there are certain medical or health conditions for which cold intolerance is common.
Thyroid Disease
Hypothyroidism, or low thyroid function, is one of the most recognized causes of cold intolerance.
The thyroid glands are responsible for producing hormones that play a central role in regulating metabolism, including how and when energy reserves in the body are used. In a cold environment, thyroid hormones can increase metabolism to help normalize your body temperature.
If you have hypothyroidism, the low output of thyroid hormones undermines this effect, making you more susceptible to the cold.
In people with hypothyroidism, hormone therapy can help normal thyroid levels and, in turn, alleviate symptoms of cold intolerance.
How Hypothyroidism Is Treated
Anemia
Anemia is a condition in which you don't have enough red blood cells to transport oxygen through the body. It can also occur if don't have enough of an iron-containing protein, called hemoglobin, that is responsible for carrying oxygen molecules.
Iron deficiency anemia is a type of anemia caused by the lack of iron in the body. Iron is not only needed to make hemoglobin but is also essential in producing ample quantities of red blood cells.
Cold intolerance is strongly linked to iron deficiency anemia for two reasons:
- Lack of oxygen: Oxygen is not only involved in the burning of calories for energy and heat but also in the narrowing of blood vessels to help conserve heat. With all types of anemia, including pernicious anemia (caused by a lack of vitamin B-12) and aplastic anemia (caused by bone marrow problems), the lack of oxygen reduces both of these effects.
- Lack of iron: Iron is also needed to produce thyroid hormones. In people with iron deficiency anemia, low iron levels reduce the production of these hormones, further increasing cold sensitivity.
Iron deficiency anemia can be treated with iron supplements and prescription drug therapies.
Raynaud’s Syndrome
Raynaud's syndromeis a condition in which a person's fingers or toes turn blue or white upon exposure to cold and then bright red upon rewarming. It is caused by the abnormal narrowing of blood vessels (vasoconstriction) in response to cold or stress. In some people, it can affect one hand or foot (or even part of the foot or hand) but not the other.
Although the cause of Reynaud's syndrome is unknown, it is often experienced in people with connective tissue disorders like scleroderma or lupus.
The abnormal constriction of blood vessels deprives the tissues of oxygen. This, in turn, reduces the skin temperature and increases its sensitivity to cold. Other symptoms include numbness, tingling, or throbbing pain.
Reynaud's syndrome is treated by managing the underlying cause, if any. It also includes avoiding cold, stress, and smoking (which increases vasoconstriction).
Anorexia
Anorexia nervosa, or simply anorexia, is an eating disorder characterized by a limited food intake. People with anorexia often eat so little that they cannot sustain basic bodily functions.
Cold intolerance is common in people with anorexia for several reasons:
- Malnutrition: The inadequate intake of food deprives the body of iron, B vitamins, folate, manganese, and sulfur needed to maintain metabolism. It also affects the production of hormones that regulate the core body temperature.
- Cachexia: Body fat helps insulate the body from cold. When enough body fat is lost, a person is less able to withstand cold. Cachexia is muscle wasting accompanied by the loss of body weight and body fat. It occurs in people with anorexia when the body has to turn to muscle and fat for fuel.
Medications, support groups, and talk therapy commonly treat people with anorexia.
How Eating Disorders Are Treated
Low Body Weight
Even in people who do not have anorexia, having a low body weight increases susceptibility to cold. However, this isn't the case for everyone, as some underweight people have a high metabolism and higher core body temperatures.
With that said, low body weight is inherently linked to less subcutaneous body fat. This is the layer of fat tissue just below the skin. The loss of this insulating layer increases the risk of cold intolerance.
In addition to reducing subcutaneous fat, low body weight is linked to an increased risk of anemia.
Diabetes
Diabetes is a group of diseases that causes excess glucose (sugar) in the blood. Persistently high glucose levels can cause progressive damage to many organs in the body, including the kidneys, circulatory system, and nerves.
Complications of diabetes can lead to cold intolerance in different ways:
- Kidney damage: Diabetic nephropathy is kidney damage caused by diabetes. When this happens, a waste product called urea can accumulate in the blood, triggering a decrease in the core body temperature. Low body temperature is characteristic of advanced kidney disease.
- Circulation problems: Persistently high blood glucose levels can damage the lining of blood vessels and reduce blood flow. This not only reduces the temperature of the legs and feet in particular but can lead to the development of slow-healing sores.
- Nerve damage: Diabetic neuropathy is nerve damage caused by diabetes. Symptoms include numbness, burning, pins-and-needles sensations, and an increased intolerance to cold. In some people, even a cold breeze can cause extreme discomfort.
Managing diabetes with diet, exercise, and medications can help you avoid complications that lead to cold intolerance.
Managing Diabetes: What You Should Know
Medications
Certain medications can cause cold sensitivity. They do so by either impeding blood circulation or damaging nerves that regulate skin sensations.
The classes of drugs commonly associated with cold sensitivity include:
- Beta-blockers: Used to treat heart disease
- Chemotherapy drugs: Used to treat cancer
- Hormonal contraceptives: Use to prevent pregnancy or treat endometriosis
- Hormone replacement therapy: Used to treat menopause symptoms and low testosterone
- Immunosuppressants: Used to prevent organ transplant rejection and treat certain autoimmune diseases
- Interferons: Used to treat cancer and certain chronic viral infections
- Statin drugs: Used to lower cholesterol
Peripheral Artery Disease
Peripheral artery disease (PAD) occurs when one or more blood vessels servicing the arms, legs, head, or trunk become partially or fully blocked. It is usually caused by the build-up of fatty deposits on the walls of arteries, referred to as atherosclerosis. PAD is common in people over 50 with a history of diabetes or smoking.
The reduced blood flow caused by PAD can increase cold sensitivity in the same way as vasoconstriction. This coldness is most commonly felt in the feet (particularly in the morning or right after exercise) but can also affect other body parts.
If left untreated, PAD can damage peripheral nerves (those located outside of the brain or spinal cord). This can lead to nerve pain that further exaggerates a person's response to cold.
PAD is treated with medications and lifestyle changes, including a low-fat diet, weight loss, and routine exercise. Severe cases may require vascular surgery.
Lack of Sleep
As odd as it may seem, chronic lack of sleep can increase your sensitivity to cold while awake.
In well-rested people, blood flow in the skin will fluctuate during sleep so that temperature changes in one part of the body change consistently with other parts of the body.
Sleep deprivation disrupts this process. As the sleep deficit builds and you lose more and more sleep, blood flow will progressively shift to the center of the body and decrease in the limbs. This promotes heat loss from the feet and hands, making them feel colder.
How Sleep Deprivation Affects Body Temperature
Sleep deprivation disrupts the circadian cycle, which regulates the pattern of sleep and wakefulness. This, in turn, interferes with the release of certain hormones that regulate sensory nerves in the skin. If this happens, the brain is less able to sense temperature changes in the arms and legs and will not redirect blood to them during sleep.
Sleep deprivation can be treated with improved sleep practices (referred to as sleep hygiene) and medications.
If sleep apnea is causing the chronic loss of sleep, a healthcare provider may recommend a device called continuous positive airway pressure (CPAP) to prevent gaps in breathing that lead to nighttime awakenings.
Nerve Issues
Cold intolerance can occur when the peripheral nerves are damaged. This typically occurs when the insulated coating on nerves, called the myelin sheath, is damaged or stripped away. This can cause nerve cells to misfire, triggering shock-like pain, numbness, tingling, or burning.
The condition, known as peripheral neuropathy, can be so extreme that the weight of a bedsheet or a light breeze can cause pain. Peripheral neuropathy can increase a person's sensitivity to cold, making it difficult to hold a cold soda or walk across a cold floor.
Causes of peripheral neuropathy include:
- Alcoholism
- Autoimmune diseases (like lupus or rheumatoid arthritis)
- Chronic kidney disease (CKD)
- Diabetes
- HIV
- Lyme disease
- Medications, including certain antibiotics, chemotherapy drugs, immunosuppressants, and HIV medications
Peripheral neuropathy can be difficult to treat but may benefit from nonsteroidal anti-inflammatory drugs (NSAIDs), anticonvulsant drugs, and antidepressants.
How Peripheral Neuropathy Is Treated
Estrogen
Estrogen is a hormone that regulates female reproduction. Estrogen levels change throughout life. including during the menstrual cycle, pregnancy, and menopause.
Fluctuating estrogen levels can increase cold sensitivity, particularly as females reach the end of their reproductive cycle.
During pre-menopause, fluctuations in estrogen can lead to the sudden onset of hot flashes followed by a steep drop in body temperature. The drop is thought to be caused by estrogen's effect on nerve receptors that regulate the widening and narrowing of blood vessels.
The same fluctuations may explain why some people experience cold intolerance right before the start of their period. The luteal phase, which occurs right after ovulation, is when estrogen levels are at their peak. These extreme hormonal changes can lead to symptoms like increased coldness and shivering.
Infection or Fever
When you have an infection like the flu or gastroenteritis, your whole body may feel cold even as you are burning up with a fever. You may even experience chills and shivers, known as rigors, that are so intense that you cannot stop.
Feeling cold during an infection is largely due to the consumption of extra energy to help fight the infection.
Rigors, on the other hand, are triggered by the presence of chemicals called pyrogens in the blood. The immune system produces pyrogens to raise the body's temperature to help fight infection. But, they can trigger a contradictory reflex resulting in severe shivering and chills.
With some infections, like atypical pneumonia (also known as "walking pneumonia"), a person may only experience a sore throat, fatigue, and a constant feeling of coldness. Although walking pneumonia is milder than regular pneumonia, recovery can take up to six weeks, during which you may always feel cold.
Bacterial infections may resolve on their own or require antibiotics. Common viral infections are often left to run their course but, in some cases, may benefit from the early use of antiviral drugs.
Fibromyalgia
Fibromyalgia is a chronic condition that causes pain all over the body as well as memory problems, fatigue, and sleep difficulty. The cause of fibromyalgia is unknown, but it is thought to be the result of multiple factors, including genetics, mood disorders, past diseases, and chemical imbalances that increase pain hypersensitivity.
Research has shown thatpeople with fibromyalgia often have trouble adapting to temperature changes and have high levels of intolerance to both heat and cold. This is thought to be caused by problems with a process known as pain inhibition in which the nervous system slows down pain signals whenever it is faced with chronic pain.
This, in turn, can lead to cold intolerance by slowing down the body's response to cold. Because the body does not respond as quickly, the person may feel cold far more intensely than others.
Physical therapy, stress reduction, and medications like antidepressants and muscle relaxants may help people with fibromyalgia better manage their symptoms.
How Fibromyalgia Is Treated
Vitamin B12 Deficiency
Vitamin B12 deficiency can cause you to feel cold. If you are deficient in this vitamin, you will likely also have other symptoms such as:
- Numbness in your hands
- Trouble focusing
- Fatigue and weakness
- Pain in the joints and muscles
- Nausea and changes in appetite
Untreated vitamin B12 deficiency can cause serious problems like neurological disease. Older people, people who have had weight loss surgery, and people who follow vegetarian diets are more likely to develop a vitamin B12 deficiency.
What Vitamin Deficiency Might Cause You to Feel Cold?
Skipping Meals
Calorie-restricted diets such as intermittent fasting or skipping meals for other reasons can lead to adverse effects such as cold sensitivity.
Calorie-restricted diets are thought to slow the resting metabolic rate, or the number of calories you burn when your body is at rest. This can cause a decrease in core body temperature, which may cause you to feel colder.
How to Stop Feeling Cold
Whether you are feeling cold because of an underlying medical condition or because you've always been sensitive to cold, there are things you can do to warm up:
- Make sure you are eating enough calories each day.
- Wear thick socks to bed or around the house.
- Choose comfortable pajamas that keep you warm without overheating.
- Dress in layers.
- Fix drafty windows.
- Drink warm liquids like herbal tea.
- Engage in exercise.
When to See a Healthcare Provider
If you've always been sensitive to cold, you probably don't need to see a healthcare provider. However, intolerance to cold that is new or gradually worsening may require evaluation.
If you have symptoms of anemia, anorexia, hypothyroidism, or other conditions associated with cold sensitivity, see your healthcare provider. Diagnosis and treatment of the underlying condition can help improve your symptoms, including cold sensitivity.
Summary
Cold intolerance is an abnormal or exaggerated reaction to cold exposure. It can occur when a person's body temperature is persistently lower due to any number of medical reasons. Or, it can happen when a person's body temperature is normal but they perceive cold differently.
The causes of cold intolerance are clustered around problems involving the circulatory system, nervous system, and endocrine (hormonal) system. Often, multiple causes are involved. Even certain medications or the lack of sleep can trigger intolerance to cold.
Frequently Asked Questions
What causes chills?
Chills are your body's response to cold temperatures but can also occur before or during an infection like the flu or malaria. Chills are caused bythe rapid contraction and relaxation of muscles that aim to bring the body temperature up.
Why are people assigned female at birth always cold?
People assigned female at birth are more susceptible to cold for many reasons, not least of which is their typically smaller body size. Studies have also shown that they tend to have slower metabolisms than people assigned male at birth, so their bodies generate less heat than assigned males of comparable body size.
