Fever typically makes a person feel hot, but there are many other possible causes of this symptom. Environmental and lifestyle factors, medications, age, hormones, and certain emotional states can all affect body temperature. However, a persistent feeling of being hot sometimes signals an underlying health condition.

Depending on the cause, a person who feels hot may sweat excessively or not sweat at all. They may have flushed or irritated skin, or their skin may remain unchanged.

In this article, we look at 11 possible causes of feeling hot without a fever. We also explain the treatment options and when to contact a doctor.

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A person can check that they do not have a fever by using a thermometer to measure their body temperature. A digital thermometer is the best option, as glass ones can be dangerous.

The Centers for Disease Control and Prevention (CDC) recommend that people measure their temperature when they are not taking fever-reducing medications, such as ibuprofen (Advil) or acetaminophen (Tylenol).

If an adult’s body temperature is 100.4°F (38°C) or higher, they have a fever. However, if their body temperature is normal, at 98.6°F (37°C), they do not have a fever.

A child will have a fever if their temperature is 99.5°F (37.5°C).

Learn more about fever in adults and children.

Many lifestyle and environmental factors can make a person feel hot but not produce a temperature. Factors include:

Heat-related illness

Hot or humid weather is taxing for the body, and it may affect some people more than others. In hot weather, a person might feel irritable and tired or find it difficult to concentrate.

In some cases, extreme temperatures or prolonged exposure to the sun can cause heat-related health conditions, such as sunburn, heat exhaustion, and, less commonly, heatstroke.

Sunburn occurs when the sun damages the skin, causing it to feel hot and sore. Heat exhaustion occurs when a person loses too much water and salt through sweating. The CDC notes that the symptoms of heat exhaustion include:

  • heavy sweating
  • cold, clammy skin
  • nausea or vomiting
  • tiredness or weakness
  • a headache
  • dizziness
  • muscle weakness or cramping

Children with heat exhaustion may be excessively tired and thirsty, with cool, clammy skin.

A person with heat exhaustion should find a cool area, drink fluids, and stop all physical activity until they feel better. If a person does not cool down or get better within 1 hour, they should seek medical help immediately.

Untreated heat exhaustion can turn into heatstroke, which can be life threatening. The symptoms include confusion, fainting, and skin that is hot and dry or changes color. A person may also become unconscious. Due to this, anyone who is with someone showing signs of heatstroke should call 911 right away.

Learn about the differences between heat exhaustion and heatstroke.

Exercise or strenuous activity

Exercising or carrying out physical tasks can increase a person’s body heat, particularly if they:

  • are not used to exercising regularly
  • exercise or carry out physical tasks in hot or humid environments
  • overexert themselves

The CDC states that athletes who train in hot weather should look out for the signs of heat-related illnesses and stop training if they feel weak or faint.

Avoiding exercise at the hottest times of the day, drinking more water, and pacing activities may help people avoid becoming too hot during exercise.

Food and drink

Certain foods and drinks can make people feel hotter than usual. These include:

  • alcohol
  • caffeine
  • spicy food
  • foods and beverages with a high temperature

People may feel extra heat in their skin or sweat more than usual during and after consuming these foods.

Clothing

Tight, restrictive, or dark clothing may increase body heat and prevent air circulation around the skin. Synthetic fibers may also trap heat and prevent sweat from evaporating. This can cause excessive warmth and increased sweating.

A range of conditions and disorders can also cause someone to feel hot. These include:

Anxiety

When a person feels stressed or anxious, they may experience physical symptoms, including feeling hot and sweaty. This happens during the “fight-or-flight” response, which increases the person’s heart rate and the blood supply to their muscles.

A person who is feeling anxious or stressed may also notice:

  • increased heart rate
  • heart palpitations
  • tense muscles
  • rapid breathing

Learn more about how anxiety affects the body.

Hyperthyroidism

Hyperthyroidism occurs when a person’s thyroid gland becomes overactive and makes too many thyroid hormones. Thyroid hormones affect how the body uses energy.

People with hyperthyroidism often experience heat intolerance, along with other symptoms, such as:

  • shaky hands
  • a rapid or irregular heartbeat
  • diarrhea or frequent bowel movements
  • difficulty sleeping
  • fatigue

Anhidrosis

Sweating is how the body keeps cool. Anhidrosis describes the inability to sweat. This symptom can affect a small or large area of the body. It may be due to an underlying condition, a medication, or blocked or injured sweat glands.

If someone cannot sweat — either at all or across a large area of their body — this could be dangerous. A person with this symptom should speak with a doctor.

Diabetes

The International Diabetes Federation explains that people with diabetes may be more sensitive to heat than people without the condition. This can be due to:

  • Dehydration: People with diabetes become dehydrated more quickly during hot weather. Not drinking enough liquids can also raise blood glucose levels, which causes a person to urinate more. This further exacerbates dehydration.
  • Complications: Diabetes can cause complications that damage the blood vessels and nerves, which, in turn, may affect a person’s sweat glands. As a result, a person may sweat less, making it more difficult for them to stay cool.

According to the CDC, the symptoms of diabetes include:

  • frequent urination, especially at night
  • feeling very thirsty and hungry
  • blurry vision
  • tingling in the hands or feet
  • fatigue
  • unintentional weight loss

People may feel hot for a variety of other reasons, including:

Pregnancy and menstrual cycles

The National Health Service (NHS) in the United Kingdom states that it is relatively common to feel hotter than usual during pregnancy and to sweat more. Hormonal changes, which increase blood supply to the skin’s surface, are responsible for these symptoms.

It is also common for the body temperature to rise during the luteal phase of the menstrual cycle, which begins after ovulation.

Menopause and perimenopause

People may experience hot flashes during, before, and after menopause. The National Institute on Aging (NIA) explains that hot flashes occur due to changing estrogen levels. Hot flashes may last anywhere from 30 seconds to 10 minutes. Other symptoms of a hot flash include:

  • flushed skin on the face and neck
  • excessive sweating
  • night sweats, which may disrupt sleep
  • feeling cold or shivery afterward

Learn more about recognizing the signs of menopause.

Medications

The International Hyperhidrosis Society lists a wide range of medications that can cause heat or sweating as a side effect. Medications that might cause a person to feel hot include:

If a person thinks that their medication might be causing side effects, they can speak with a doctor to discuss their options.

The treatment for feeling hot without a fever depends on the underlying cause.

People who feel hot due to environmental or lifestyle factors, such as sun exposure or dietary habits, may feel better if they adjust their daily routine. The CDC recommends:

  • wearing lightweight, pale, loose-fitting clothing
  • staying in air-conditioned spaces, if possible
  • taking a cool shower or bath
  • drinking plenty of fluids and replacing electrolytes lost through sweat
  • avoiding spicy foods, caffeine, and alcohol

These strategies may also help people who are pregnant and those experiencing hot flashes.

People who feel hot due to anxiety or stress may also benefit from relaxation techniques that calm the nervous system.

These include deep breathing, yoga, and tai chi. Stress can exacerbate hot flashes, so these techniques may also help people in perimenopause or menopause, according to the NIA.

A person experiencing frequent anxious thoughts may find a form of therapy, such as cognitive behavioral therapy (CBT), helpful for reducing the physical symptoms of anxiety.

However, if these strategies do not help, the individual may have a condition that requires medical treatment.

If someone frequently or continuously feels hot with no fever, they should speak with a doctor. The doctor may need to perform tests, such as blood or urine tests, to diagnose the underlying cause.

If someone is experiencing heatstroke or has symptoms of heat exhaustion that do not improve within an hour, it is important to seek emergency help.

People may feel hot for many reasons other than a fever. Some causes may be temporary and easy to identify, such as eating spicy foods, being in a humid environment, or experiencing stress and anxiety.

However, some people may feel hot frequently for no apparent reason. In such cases, it could be a symptom of an underlying condition. Anyone who is unsure why they are feeling hot with no fever should consider speaking with a doctor.