Feeling hot and cold simultaneously, often with sweating (cold sweats), usually signals your body is responding to stress, infection, or hormonal shifts, like anxiety's "fight-or-flight" response, a developing fever, or menopause, where your body's temperature regulation gets confused, causing internal heat despite feeling chilly and clammy. It's your body's alarm system, so if it happens often or with other symptoms, see a doctor to find the underlying cause, which could range from low blood sugar to thyroid issues.
Even if you have a high temperature, you might actually feel cold and begin to shiver. Your immediate reaction may be to huddle up under lots of blankets to feel warm. But even though you feel cold, inside your body is very hot. You will generally start to feel better when your temperature comes down.
Some people might feel chilled after a hot flash because of loss of body heat. Night sweats are hot flashes that happen at night. They can disturb sleep. The time when is when menstrual periods get less regular and then stop, called menopause, is the most common cause of hot flashes.
COVID-19 symptoms can include: a high temperature – you may feel hot, cold or shivery, or your skin is hot to touch on your chest or back (you do not need to measure your temperature)
Feeling cold can stem from deficiencies in iron, Vitamin B12, and sometimes folate, which often lead to anemia, impairing oxygen and heat transport; other causes include issues with thyroid function (linked to iron/zinc), poor circulation from deficiencies like magnesium or Omega-3, and dehydration. These deficiencies reduce your body's ability to generate and distribute heat, commonly causing cold hands and feet.
B12 deficiency can trigger specific food cravings, most notably for meat, fish, or eggs, as the body seeks animal-based sources to replenish the vitamin, especially in those on vegetarian/vegan diets or older adults. While cravings for sugary or salty foods can also signal general B-vitamin issues, the distinct urge for protein-rich animal products is a key indicator, but professional testing is crucial for confirmation.
Iron deficiency anemia is one of the primary causes of cold sensitivity. Other causes of anemia include vitamin B12 deficiency, folate deficiency and chronic conditions like kidney disease or gastrointestinal bleeding. If you often feel cold, you might have low iron.
Possible symptoms include:
Stay cool
Help lower your body temperature by creating a cool environment. Wear lightweight clothing and keep your room at a comfortable temperature. While you may feel cold or have chills when running a fever, it's best to avoid over-bundling yourself in heavy blankets, as this can trap heat and worsen your fever.
Definition. Severe chills with violent shivering. A rigor is an episode of shaking or exaggerated shivering which can occur with a high fever. [ from HPO]
Being deficient in vitamin B12 can affect the body's ability to produce enough red blood cells, which are responsible for carrying oxygen to tissues and organs, including those that regulate our body temperature and stop us feeling too hot or too cold.
Hot Flashes & Night Sweats
Hyperthyroidism can cause symptoms similar to hot flashes, such as excess sweating, high body temperature, and heat intolerance. For both people in the menopause transition and people with thyroid disorders, hot flashes can lead to overheating and sweating while you sleep.
Common causes of cold sweats
The most common causes include: Stress and anxiety: Anxiety can trigger cold sweats as part of the body's natural fight-or-flight response, which is designed to protect us from dangerous situations. If you are overly anxious, your body releases sweat – even if you feel cold.
The Hot And Cold Experience
These "Flashes" are really just changes to your body temperature. During periods of intense anxiety, your body temperature heats up due to vasoconstriction, which is when your blood vessels tense up as they deliver more blood to the areas involved in fight and flight.
Viruses that can cause hyperpyrexia include enterovirus infection, roseola, rubeola, and malaria. Hyperpyrexia is associated with a body temperature of more than 106.7°F or 41.5°C. Typically, treatment for hyperpyrexia focusses on the underlying disease, if one exists.
Extreme low blood pressure can lead to a condition known as shock. Symptoms of shock include: Confusion, especially in older people. Cold, clammy skin.
Once the higher temperature is set, your body begins working to increase its temperature. You will feel cold because you are now at a lower temperature than your brain thinks you should be so your body will begin to shiver to generate heat and raise your temperature. This is the chills.
A lukewarm, not hot, bath can help reduce a fever and relax you so you can sleep better. 3 Be sure to get out of the tub once the water starts to cool. Avoid taking a cold bath or shower, and avoid using ice.
Researchers in Japan have pinpointed a biological cause of Long COVID brain fog using advanced PET brain imaging. They discovered widespread increases in AMPA receptor density linked to cognitive impairment and inflammation.
You can't tell if you have COVID-19 or the flu just by symptoms because they overlap significantly (fever, cough, fatigue), but testing is the only way to know for sure; seek rapid combination tests or see a doctor for diagnosis and early treatment, as both viruses have specific antivirals that work best when given quickly, and having both can be more severe.
Covid cases rising with new variants Nimbus and Stratus. If you feel unwell with a bad throat and a temperature you may well have caught one of the new strains of Covid circulating this autumn. XFG, called Stratus by some, and NB. 1.8.
Blood cancers such as leukemia and lymphoma are most commonly linked to chills, since they may affect how your body makes and fights off infection. Kidney cancer and other advanced cancers may also cause unexplained chills or fevers.
However, with so many potential culprits, it can be hard to know what vitamin deficiency causes you to feel cold. Typically, it's a lack of vitamin B12 or iron. Iron deficiency can slow down thyroid function, which can lead to a condition called hypothyroidism, making you feel cold.
In addition to hormones and your thyroid, Dr. Luft says dehydration makes you cold. “If you're dehydrated, your body works harder to circulate blood. To conserve energy and keep your organs warm, there's reduced blood flow to your extremities, like your hands and feet, making them feel colder.”