Feeling cold all the time usually signals that your body is either producing less internal heat than it should, losing heat faster than normal, or struggling to sense temperature accurately. The causes range from straightforward (not eating enough, poor sleep) to medical conditions that need attention, like thyroid problems or anemia. Understanding which category you fall into can help you figure out whether this is something to manage on your own or bring to a doctor.
Your Body’s Internal Furnace
Your body generates heat as a byproduct of metabolism. Every cell burning fuel for energy releases warmth, and your brain constantly adjusts blood flow, shivering, and sweating to keep your core temperature in a tight range. That range, by the way, is lower than most people think. A Stanford Medicine analysis of over 618,000 temperature readings found that the average adult body temperature is about 97.9°F, not the old textbook figure of 98.6°F, with a normal range spanning roughly 97.3°F to 98.2°F.
When any part of this system underperforms, you feel cold. The problem could sit at the level of heat production (metabolism), heat distribution (blood circulation), or heat perception (nerve function). Most causes of chronic cold sensitivity fall into one of these three buckets.
Thyroid Problems and Metabolism
The thyroid gland is the single biggest player in how much heat your body generates at rest. Thyroid hormones directly control the rate at which your cells burn energy, and they activate specialized heat-producing processes in muscle and fat tissue. When thyroid hormone levels drop, as in hypothyroidism, your metabolic furnace turns down. You produce less heat, and you feel it.
This isn’t subtle. Hypothyroidism affects roughly 5% of adults, and cold intolerance is one of its hallmark symptoms, alongside fatigue, weight gain, dry skin, and brain fog. If you’ve noticed several of these together, a simple blood test measuring thyroid-stimulating hormone (TSH) can confirm or rule it out. Treatment with thyroid hormone replacement typically resolves the cold sensitivity within weeks.
Iron Deficiency and Anemia
Iron deficiency is one of the most common nutritional deficiencies worldwide, and it directly impairs your ability to stay warm. When you don’t have enough iron, your body can’t make adequate hemoglobin, the protein in red blood cells that carries oxygen. Fewer functional red blood cells means less oxygen delivered to tissues, and less oxygen means less fuel burned for heat.
But the connection goes deeper than just reduced heat production. Research from the National Academies of Sciences found that iron-deficient anemic individuals lose the ability to properly control blood vessel constriction in their extremities. Normally, when you’re cold, your blood vessels narrow near the skin surface to keep warm blood closer to your core. In iron deficiency, this mechanism fails, so you lose heat through your skin faster than you should. Iron-deficient people also show a blunted thyroid response to cold, meaning the hormonal signal that should ramp up heat production doesn’t fire properly. Correcting the anemia by restoring red blood cell levels fixes both problems.
Women with heavy menstrual periods, vegetarians, and frequent blood donors are at higher risk. If your cold sensitivity comes with pale skin, unusual fatigue, or shortness of breath on exertion, iron levels are worth checking.
B12 Deficiency
Vitamin B12 plays a role similar to iron in this story. Your body needs B12 to produce healthy red blood cells, so a deficiency leads to a type of anemia that reduces oxygen delivery and heat production. B12 deficiency also damages nerve cells over time, which can cause numbness and tingling in the hands and feet. That nerve damage may alter how you perceive temperature, making cold sensations feel more intense or persistent. Adults over 50, people on acid-reducing medications, and those following strict plant-based diets are most vulnerable to B12 deficiency.
Poor Circulation and Raynaud’s Phenomenon
If your cold sensitivity is concentrated in your fingers and toes rather than all over, circulation is the likely culprit. The most dramatic version of this is Raynaud’s phenomenon, a condition where small blood vessels in the fingers and toes overreact to cold or stress. During an episode, the affected digits turn white as blood flow cuts off, then bluish as remaining blood loses oxygen, then red and painful as circulation returns. Attacks can last minutes to hours.
Raynaud’s affects up to 5% of the population and is far more common in women. The primary form has no underlying disease and is mostly a nuisance. The secondary form can accompany autoimmune conditions like lupus or scleroderma, and a doctor can distinguish between the two by examining the tiny blood vessels at the base of your fingernails under magnification. Severe cases can cause small painful sores at the fingertips, though this is uncommon.
Even without Raynaud’s, some people simply have less efficient peripheral circulation. Sitting for long periods, smoking, and conditions like peripheral artery disease all reduce blood flow to the extremities and make you feel colder.
Medications That Make You Cold
Several common medications cause cold hands and feet as a side effect. Beta-blockers, prescribed for high blood pressure, heart conditions, and migraines, constrict small blood vessels and reduce blood flow to the hands and feet. If your cold sensitivity started around the time you began a new medication, that connection is worth raising with your prescriber. Other drugs that can contribute include certain migraine medications and some ADHD stimulants during their “wearing off” phase.
Sleep, Stress, and Body Composition
Sleep deprivation disrupts temperature regulation in ways researchers are still mapping out. Neuroscience research at Washington University in St. Louis found that the same neurons controlling sleep also regulate temperature preference, and that disrupting sleep changes how the body manages its thermal set point. If you’re chronically underslept, your internal thermostat may genuinely be off.
Body composition matters too. Body fat acts as insulation, and muscle generates heat even at rest. People with very low body fat or limited muscle mass produce and retain less heat. This is one reason why cold intolerance is common in eating disorders and extreme dieting, and why older adults who have lost muscle mass tend to feel cold more easily.
Dehydration is another overlooked factor. Water holds heat well, and when you’re dehydrated, your blood volume drops, reducing circulation to your skin and extremities. Simply not drinking enough throughout the day can make you feel noticeably colder.
Nerve Damage and Temperature Perception
Sometimes the problem isn’t that you’re actually colder. It’s that your nerves are sending inaccurate signals. Diabetic neuropathy, the most common form of nerve damage in the U.S., typically starts in the feet and legs before progressing to the hands. It can reduce your ability to feel pain or temperature changes, but it can also create abnormal sensations, including persistent feelings of coldness, burning, or tingling. Symptoms tend to be worse at night. If you have diabetes or prediabetes and notice unusual temperature sensations in your feet, this is worth discussing with your care team.
When Cold Sensitivity Needs Medical Attention
Feeling chilly in an air-conditioned office is normal. Persistently feeling cold when others around you are comfortable, or noticing a change in your cold tolerance that wasn’t there before, is different. The symptoms that should prompt a medical evaluation include cold sensitivity that is new and doesn’t improve, cold fingers or toes with visible color changes, fatigue or unexplained weight gain alongside the cold feeling, numbness or tingling in the extremities, and hair loss or unusually dry skin. A basic workup including thyroid function, a complete blood count, iron levels, and B12 can identify or rule out the most common medical causes. Many of them are straightforward to treat once identified.