Thyroid & Cold Intolerance…Heat Intolerance Too!

Thyroid & Cold Intolerance...Heat Intolerance Too!

I’m cold. All. The. Time.

I need to wear a sweater in summer to keep from freezing.

My body just can’t handle the air conditioning in my workplace.

But what about me? I’m hot all the time.

Here I am wearing a sleeveless shirt in the dead of winter.

Sleep without my fan? Impossible.

Written by Kent Holtorf, MD

Thermoregulation and Cold Intolerance

As the temperature drops, the thyroid must work harder to maintain various aspects of bodily function including thermoregulation and metabolism. A primary role of the thyroid is thermoregulation, which helps keep the body at a healthy temperature of 98.6 degrees Fahrenheit or 37 degrees Celsius.

Those with thyroid conditions tend to be less capable of dealing with cold weather. Inability to maintain proper body heat can lead to cold intolerance.

In fact, some of the most common causal factors of cold intolerance involve hormone function. There are three major contributors that are commonly found in those who are cold intolerant.

♦ Hypothyroidism, reduced thyroid activity, leads to a reduced metabolic rate. As metabolism reduces, the body becomes decreasingly effective at producing heat.

♦ Hyperthyroidism, overactive thyroid activity, can cause individuals to have less fat and reduced muscle mass. Both fat and muscle act as a sort of insulation and help regulate body heat.

♦ A dysfunctional hypothalamus, the gland located in the brain that regulates core body temperature, can cause significant fluctuations in body temperature. If this system malfunctions, body temperatures can be allocated to improper ranges.

Cold Weather and The Thyroid

Cold weather has a notable impact on those with thyroid conditions, but it can also impact the thyroid of healthy individuals. Because the body requires more heat, it produces additional TSH in order to boost metabolic action. Due to this influx of TSH (this commonly occurs during extended periods of cold weather), one may be incorrectly diagnosed with mild hypothyroidism, or subclinical hypothyroidism. To avoid misdiagnosis, it is best to have multiple tests done in different seasons as hormone levels fluctuate dependent on moderate and cold seasons.

In a 2013 study, published in the Journal of Clinical Endocrinology & Metabolism, a shift was recognized in thyroid stimulating hormone (TSH) levels based on the season. Tests gauging TSH levels were conducted monthly among 1,751 individuals diagnosed with subclinical hypothyroidism and 28,096 healthy individuals with normal thyroid function. Results showed that there is a definite seasonal pattern in TSH levels. In both groups, levels of TSH decreased during the summer and fall months and increased during the winter months all the way through to the spring. This data, as suggested by David S. Cooper, MD, could be the body compensating for cold weather by increasing hormone production and thereby boosting metabolic function. As this study shows, a thyroid condition is not required to feel the impact of system-slowing effects brought on by cold weather.

Those with thyroid conditions have reduced tolerance to cold and are at greater risk of hypothermia. Additionally, research shows that living in a colder climate is also a risk factor for developing thyroid cancer. Researchers looked at correlations between average temperature by state, and the rates of thyroid cancers. (They adjusted for exposure to radiation, a key risk factor for thyroid cancer.) What they found was that living in colder areas significantly increases the risk of developing thyroid cancer. For example, living in Alaska actually doubled the risk of thyroid cancer, compared to a warmer state such as Texas. Maybe the snowbirds who head to a warmer climate for the winter have the right idea!

The Weather and Your Thyroid Medication

If you are hypothyroid, you may notice that if you stay on a steady dose of thyroid hormone replacement medication during colder months, you may feel somewhat more hypothyroid. Some physicians routinely recommend that their hypothyroid patients raise their medication dosage slightly during colder months, and drop back down to a lower dose during warmer temperatures. If you notice hypothyroidism symptoms becoming more troublesome during colder weather, you may want to ask your doctor about a seasonal dosage adjustment.

What About Heat Intolerance and The Thyroid?

A frequently overlooked indicator of thyroid dysfunction is intolerance to warmer conditions.

Typically, this symptom presents itself in hyperthyroid patients. However, any form of thyroid dysfunction, especially those related to autoimmune dysfunction, can result in a person suffering from poor temperature regulation.

Recognizing the lesser known symptom of heat intolerance and its relation to thyroid function is an important step in identifying and treating thyroid dysfunction.

When functioning correctly, the thyroid actively responds to changes in temperature by appropriately adjusting basal metabolic rate (BMR) and releasing hormones to promote cellular release or retention of heat. This action keeps the body at a comfortable and functional temperature. However, when the thyroid is not at its best, the body loses much of its capacity to regulate temperature.

Intolerance to cold or an inability to stay warm is a common indicator of hypothyroidism. Hyperthyroidism causes overactive cell function resulting in multiple symptoms including sensitivity to heat. While this is the most common presentation of symptoms, the opposite is possible as well and can make symptoms confusing to interpret.

Autoimmunity and Hashimoto’s

A number of hypothyroid patients suffer from some degree of autoimmune dysfunction resulting in multiple issues including heat intolerance.

Hashimoto’s thyroiditis is a common autoimmune disorder. Hashimoto’s causes the body’s defenses to attack its own thyroid tissue. Symptoms of Hashimoto’s manifest differently depending on the patient. There are multiple symptoms associated with Hashimoto’s but the intensity and frequency of such symptoms can be drastically varied. Generally, symptoms begin mild and then continue to intensify over time if inflammation and the malfunctioning immune response is not resolved.

Common symptoms of Hashimoto’s include:

♦ Fatigue
♦ Weight gain
♦ Altered mood, particularly malaise and depression
♦ Difficulty maintaining focus
♦ Dry skin or lips, rashes, and brittle hair
♦ Constipation
♦ Fluid retention leading to bloating in the face and lower extremities
♦ Hoarseness or difficulty speaking
♦ Inability to sweat or reduced perspiration
♦ Heat sensitivity
♦ Changes in menstruation
♦ Joint and muscle pain

Hashimoto’s Hormone Spikes and Hot Flashes

Patients with Hashimoto’s experience a range of symptoms alternating between hypothyroidism and hyperthyroidism. This is caused by damage being done directly to the thyroid that limits hormone production resulting in a net loss of thyroid hormone. However, as portions of the thyroid are destroyed there is a temporary release of thyroid hormone that can temporarily elevate hormone levels. A spike in thyroid hormone such as this can result in symptoms related to hyperthyroidism including extreme susceptibility to heat and hot flashes. This can occur even though the patient’s thyroid production indicates hypothyroidism.

Temporary hormone spikes can result in episodes of fatigue, hot flashes, anxiety, jitteriness, and weight fluctuations. Furthermore, patients can suddenly become incapable of cooling down when they were previously unable to stay warm. This can be highly jarring for those with hypothyroidism.

Overmedicated hypothyroid patients experience issues similar to Hashimoto’s-related hormone spikes. Over supplementation of thyroid hormones may push a hypothyroid patient into hyperthyroid states resulting in many different symptoms including heat intolerance.

Triggered Symptom Flares

Hashimoto’s symptoms can alter over time and periodically flare up or temporarily worsen due to different triggers. Flares generally exacerbate current symptoms.

If a patient is experiencing Hashimoto’s related symptoms such as sensitivity to heat, a flare up can abruptly worsen their already reduced ability to regulate body temperature. Usually, autoimmune flare ups have an external trigger.

Those with autoimmune disorders have a highly sensitive and reactive immune system. This means that even minor changes in diet, activity level, stress, allergen exposure and others can trigger an immune response resulting in increased symptom intensity.

A Hashimoto’s-related flare up may be identified through the following symptoms:

♦ Abrupt worsening of fatigue
♦ Unexplained weight gain
♦ Malaise or depression
♦ Sudden worsening of joint pain, muscle pain, and weakness
♦ Anxiety, jitteriness, and racing heart
♦ Abrupt onset of brain fog and difficulty concentrating 
♦ Digestive issues or changes in gastrointestinal function
♦ Hot flashes or difficulty regulating body temperature

Regardless of the symptoms that manifest, it’s most important to identify what initiated the response. Recognizing the trigger allows patients to avoid and minimize future autoimmune and inflammatory responses, which helps reduce symptom occurrence and intensity.

Common autoimmune triggers include:

♦ Physiological or emotional stress
♦ Physical trauma including sport related injury, car accident, etc.
♦ Chronic nutrient deficiencies
♦ Viral, bacterial, or fungal infections
♦ Hormone imbalances
♦ Food allergies or sensitivities
♦ Stress
♦ Lack of sleep

Remember to listen to your body and respond appropriately. If you feel cold or hot quicker than others and just can’t seem to warm up or cool down no matter what you do, get checked for thyroid dysfunction. An abnormal reaction to heat or cold may serve as a sign of thyroid dysfunction that is undiagnosed or not well treated.

About Dr. Kent Holtorf

Kent Holtorf, M.D. is the medical director of the Holtorf Medical Group with locations in Los Angeles, Foster City, Atlanta, and Philadelphia. He is also founder and director of the non-profit National Academy of Hypothyroidism (NAH), which is dedicated to dissemination of new information to doctors and patients on the diagnosis and treatment of hypothyroidism.

Dr. Holtorf has personally trained numerous physicians across the country in the use of bioidentical hormones, hypothyroidism, complex endocrine dysfunction, and innovative treatments of chronic fatigue syndrome, weight loss, fibromyalgia, and chronic infectious diseases, including Lyme disease. He has been a featured guest on numerous TV shows including CNBC, ABC News, CNN, EXTRA TV, Discovery Health, The Learning Channel, The Today Show, The Doctors, Dr. Dean Edell, Glenn Beck, Nancy Grace, Fox Business, ESPN, Rush Limbaugh, CBS Sunday Morning, Sean Hannity, So Cal News, and quoted in numerous print media including the Wall Street Journal, Los Angeles Times, US New and World Report, San Francisco Chronicle, WebMD, Health, Elle, Better Homes and Garden, US Weekly, Forbes, Cosmopolitan, New York Daily News, Self magazine, among many others.

READ NEXT: When Hypothyroidism is Painful: Musculoskeletal Manifestations

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About Dana Trentini

Dana Trentini founded Hypothyroid Mom October 2012 in memory of the unborn baby she lost to hypothyroidism. This is for informational purposes only and should not be considered a substitute for consulting your physician regarding medical advice pertaining to your health. Hypothyroid Mom includes affiliate links including the Amazon Services LLC Associates Program.


  1. I have an underactive thyroid, ulcerative colitis and menapausal, I’m on the lowest dosage of thyroxine as any higher sends my heart rate through the roof. My skin pinks up when I am burning hot which is 90% of the time, the rest of the time I’m freezing cold, I eat healthy but have gained approx half a stone a year for last 12 yes, only time i lose weight is if I have a major colitis flare up and end up in hospital and can lose 2-3 stones in couple of weeks, then gain it back with endless steroids for next few months. I get major joint pains and take vitamins etc to help, I now also have gall stones and plantaris in my feet so also had injections to help with that. I wish there was something to help me.

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