What are the other Names for this Condition? (Also known as/Synonyms)

• Heat Hypersensitivity
• Intolerance to Heat
• Sensitivity to Heat

What is Heat Intolerance? (Definition/Background Information)

• Heat Intolerance is a feeling of extreme overheating when there is a rise in temperature; it often results in excess sweating. Such a Heat Sensitivity makes it impossible for one to be comfortable in hot weather and is normally a symptom an underlying condition
• According to some reports, the definition of Heat Intolerance means a body temperature of 101.3 deg F and over 150 heartbeats per minute. It may be also accompanied by other signs and symptoms such as sweating, vomiting, tiredness, and fainting
• Heat Intolerance may be observed in individuals of any age range and is commonly caused by use of medications, high caffeine intake, and certain medical conditions. The condition can result in nausea, high fever, and body cramps
• The treatment of Heat Intolerance is based on the severity and type of the underlying condition. With proper and early treatment, the condition may last for a couple of days, but the prognosis is usually good

Who gets Heat Intolerance? (Age and Sex Distribution)

• Any individual has the potential of experiencing Heat Intolerance as it has a broad variety of underlying causes
• Both males and females are affected, and no gender predilection is seen
• Worldwide, individuals of all races and ethnicities may be affected

What are the Risk Factors for Heat Intolerance? (Predisposing Factors)

The risk factors associated with Heat Intolerance include:

• Rapid/sudden exposure to heat
• Taking certain medications
• Being a young child
• Being over the age of 65
• Genetic adverse response to heat
• Physiological inability of the body to regulate heat

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Heat Intolerance? (Etiology)

Heat Intolerance is experienced when the body cannot regulate its raised body temperature. It is caused when the body’s thermoregulatory system (the hypothalamus in the brain) is impaired and dysfunctional, generally due to an underlying factor.

The common causes of Heat Intolerance include:

• High caffeine intake
• Menopause
• Hyperthyroidism (Graves’ disease)
• Multiple sclerosis
• Hypothalamic disease
• Diabetes
• Amphetamine use
• Medications for blood pressure, congestion, and allergies

Caffeine and certain medications may trigger Heat Intolerance in individuals.

What are the Signs and Symptoms of Heat Intolerance?

The signs and symptoms of Heat Intolerance include:

• Nausea
• Weakness
• Muscle cramps
• Headache
• Heavy sweating
• Increased heart rate
• Dizziness
• High fever (between 100.4°F and 104.9°F)
• High heart-rate

It is observed that individuals with multiple sclerosis and Heat Intolerance may experience temporary loss of vision or blurry vision.

The onset of Heat Intolerance is usually gradual, but it has the potential to last a long time. In some instances, the onset may be sudden. However, this frequently depends on the underlying cause.

How is Heat Intolerance Diagnosed?

Diagnoses of Heat Intolerance will likely go in tandem with a diagnosis of the underlying condition. A physician will need to determine what is causing the signs and symptoms and may conduct various tests to rule out the potential causes.

Common tests and exams used to diagnose Heat Intolerance may include:

• Complete physical exam and medical history evaluation
• Rectal temperature check to see core temperature of the body
• Thyroid hormone analysis
• Blood tests, as necessary
• Nerve and muscular examination
• Electrocardiogram
• In postmenopausal women, exclusion of hot flashes may be considered by the healthcare provider

Many clinical conditions can have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Heat Intolerance?

The most serious complication associated with Heat Intolerance is heat exhaustion. Heat exhaustion can result in a potentially fatal heat stroke if left untreated. The signs and symptoms of a heat exhaustion may include:

• Rapid heart rate and fast breathing
• Confusion
• Elevated body temperature of 104 deg F or more
• Nausea and vomiting
• Unconsciousness

Also, if the heat exposure is extreme, then Heat Intolerance may result in a medical emergency such as a heat stroke.

How is Heat Intolerance Treated?

The treatment of Heat Intolerance is generally undertaken on a case-by-case basis. The signs and symptoms are generally managed by:

• Keeping the body cool; staying in cool environments or sucking on ice cubes
• Staying well-hydrated (drinking plenty of water)
• Avoiding strenuous activity
• Wearing lightweight clothing in hot weather
• Use of cooling vests, if needed

The underlying condition causing the Heat Intolerance signs and symptoms needs to be addressed and will require a specific treatment plan.

How can Heat Intolerance be Prevented?

In some cases, Heat Intolerance may be prevented by adhering to some of the following factors:

• Undertaking early adequate treatment of the underlying cause
• Staying in a cool setting
• Wearing light fabrics
• Maintaining a healthy weight
• Remaining hydrated; replenishing body fluids and electrolytes in a timely manner and adequately
• Avoiding alcohol and caffeine on hot days, prior to any physical activity
• If medications are the cause, avoiding the same or taking alternative medicines

What is the Prognosis of Heat Intolerance? (Outcomes/Resolutions)

• In most cases, a Heat Intolerance typically lasts up to two days when managed adequately
• If the condition is treated properly the prognosis is usually good; however, the severity of the underlying cause may dictate overall outcomes 

Additional and Relevant Useful Information for Heat Intolerance:

The following link provides useful information for a heat stroke:

https://www.dovemed.com/healthy-living/first-aid/heat-stroke/