Heat intolerance is an unusual sensitivity to heat. People with heat intolerance may feel hot when others feel comfortable or cold. Heat intolerance causes may include conditions that cause dysautonomia, which affects the autonomic nervous system.
They may also have an unusual response to heat, such as intense sweating or anxiety. Heat intolerance is not a disease, but it can be a symptom of an underlying medical condition.
In this article, learn about the causes of heat intolerance, how to manage it, and when to see a doctor.
Heat intolerance is a generic symptom that can refer to a wide variety of responses to heat.
Some people with heat intolerance merely dislike the heat. Others feel uncomfortably hot at temperatures that other people find comfortable.
People may be more susceptible to the effects of heat if they have a health condition
- diabetes
- obesity
- an infection
- a skin disorder, such as eczema or psoriasis
- sickle cell trait
- cardiovascular disease
- an alcohol use disorder
- hyperthyroidism
Certain medications, such as diuretics, may increase a person’s sensitivity to heat. Older adults and young children may also be more susceptible. Athletes and outdoor workers may also have a higher risk of heat-related illness.
Some people can develop serious or even life threatening symptoms in response to heat. According to the
People with heat intolerance need to be cautious in extreme heat, especially when they have other risk factors for heat-related illnesses.
The symptoms of heat intolerance can vary from person to person but
- feeling very hot in moderately warm temperatures
- excessive sweating
- not sweating enough in the heat
- exhaustion and fatigue during warm weather
- nausea, vomiting, or dizziness in response to heat
- changes in mood when too hot
People with certain chronic illnesses, such as multiple sclerosis (MS), may find that their symptoms temporarily worsen in the heat. Some people with heat intolerance also have cold intolerance.
Heat exposure
People with heat intolerance should be aware of signs and symptoms that
- Heatstroke: This is a medical emergency. Heatstroke can lead to seizures and a loss of consciousness and can quickly become fatal.
- Heat exhaustion: In heat exhaustion, the body loses excessive water and salt, usually due to sweating. This can lead to dizziness, headache, nausea, and other symptoms.
- Rhabdomyolysis: Prolonged heat exposure and exertion can lead to a rapid breakdown, rupture, and death of muscle tissue, known as rhabdomyolysis. This can result in a release of electrolytes and other substances that can, in turn, cause an irregular heart rate, seizures, and kidney damage.
- Heat syncope: A person faints or becomes dizzy due to standing too long, dehydration, and heat exposure.
- Heat cramps: Excessive sweating can lead to a loss of water and minerals in the body. A person may experience pain, muscle cramps, or spasms in the legs, arms, or abdomen.
- Heat rashes: Sweating can result in areas of inflamed skin and clusters of pimples or small blisters known as heat rash or prickly heat.
- Heat edema: Swelling and discomfort occur in the hands and feet
due toTrusted Source blood vessel dilation and the pooling of fluids, for example, in the ankles.
Those with heat intolerance may have a disorder called dysautonomia that affects their autonomic nervous system.
The autonomic nervous system helps regulate automatic functions of the body, including the body’s response to heat.
Several medical conditions can cause dysautonomia, including:
- diabetes
- alcohol use disorder
- Parkinson’s disease
- Guillain-Barré syndrome
Other factors that could increase the risk of heat intolerance include:
- Age: Infants, children under 4 years old, and older adults
may beTrusted Source more sensitive to the heat. This sensitivity increases their susceptibility to heat-related illnesses, such as heatstroke. - Medication: Some medications change the body’s response to heat, for example, by decreasing sweat production. Anticholinergic drugs, which can treat many psychiatric conditions and Parkinson’s disease,
may reduceTrusted Source sweating and increase heat sensitivity. - Sensory issues: Sensory processing disorder, as well as sensory issues that sometimes accompany autism,
may makeTrusted Source a person more sensitive to heat. - Neurological conditions: Medical conditions that affect the brain and spinal cord, such as
spinal cord injuriesTrusted Source and MS, can increase heat sensitivity by changing how the body or brain processes heat or inhibiting the body’s ability to regulate temperature. - Endocrine system problems: The endocrine system helps the body regulate a wide range of functions. Disorders such as Graves’ disease, a thyroid condition, can increase heat sensitivity.
- Being less physically fit: For some people, heat intolerance is a sign of low fitness or low body weight.
People with heat intolerance should discuss their symptoms with a doctor, especially if they appear suddenly or get progressively worse.
Doctors will focus on treating any underlying medical conditions to treat heat intolerance. Treatment will vary widely depending on the underlying condition. For example, people with Graves’ disease may need to restore normal thyroid levels with radioiodine therapy.
In many cases, heat intolerance is not fully preventable or treatable. A person with a spinal cord injury may have difficulty in extreme heat no matter what treatment they choose.
People may find that avoiding heat where possible and adopting strategies for safely managing any necessary time in hot conditions will help in the long term. Ways to manage heat intolerance include:
- Avoiding direct sunlight. The sun tends to be at its hottest and brightest between 11 a.m. and 3 p.m.
- Using air conditioning or a fan during the summer months.
- Drinking plenty of fluids to avoid dehydration.
- Wearing light-colored, loose-fitting clothing.
- Avoiding alcohol in hot weather.
- Taking a cool bath or swimming in a pool.
- Wrapping a towel soaked in cold water around the back of the neck.
- Avoiding strenuous activities during hot weather or in warm rooms.
People with heat intolerance should carefully monitor themselves for signs of heat-related illness,
- nausea
- dizziness
- very heavy sweating
- muscle cramps
- a headache
- fainting
Seek immediate medical attention for:
- an inability to sweat, even when very warm
- a body temperature above 103°F
- confusion
- loss of consciousness
Managing medical conditions that cause heat intolerance can help prevent symptoms.
A person should talk with a doctor about staying safe in the heat and ask whether any medications are available to help the body regulate its temperature.
Some strategies that can reduce the risk of heat intolerance
- Maintaining a healthy body weight. Heavier people may have more difficulty cooling their bodies.
- Getting plenty of exercise to remain physically fit. People with good heart and lung health tend to respond better to the heat.
- Limiting or avoiding alcohol and drug use. Excessive alcohol consumption and the abuse of some drugs, such as amphetamines, may increase heat sensitivity.
- Keeping blood sugar levels in check. People with diabetes may be more vulnerable to the heat, especially when their blood sugar levels are too low or too high.
- Drinking plenty of water. Extreme heat saps the body of water through sweating. If the body cannot sweat, it cannot stay cool, so staying hydrated is critical.
- Taking time to acclimatize: People going to a hotter place on holiday, for instance, can spend more time outdoors as they become accustomed to the heat.
Does low estrogen cause heat intolerance?
Yes, low estrogen levels can cause heat intolerance, particularly in women experiencing perimenopause or menopause.
Estrogen plays a key role in regulating body temperature and can lead to symptoms such as hot flashes and night sweats when levels are low.
What autoimmune disease causes heat intolerance?
Several autoimmune diseases can cause heat intolerance, including:
- multiple sclerosis
- Grave’s disease
- rheumatoid arthritis
- systemic lupus erythematosus
Does fibromyalgia cause heat intolerance?
Yes, fibromyalgia can cause heat intolerance. A person with this condition may feel too hot or too cold as they are unable to regulate their body temperature properly.
As many people enjoy outdoor activities, such as swimming and warm-weather festivities, those with heat intolerance may feel frustrated and excluded. However, the right treatment strategy and a few cooling measures may make the heat feel more manageable.
Heat intolerance can provide clues to a person’s overall health. It suggests that either the body may not be able to cool itself down properly, the brain may not be responding correctly to heat, or the heart and lungs may be struggling to work efficiently enough.
Anyone experiencing new or worsening heat intolerance should speak to a doctor who can help diagnose the underlying problem.
