The body constantly works to maintain a stable internal temperature, a process known as thermoregulation, typically around 98.6°F (37°C). While a stable internal temperature is generally maintained, you might often feel hot to the touch. This sensation usually indicates a temporary adjustment by the body’s internal thermostat, the hypothalamus in the brain, in response to various internal or external factors.
Normal Physiological Adjustments
Feeling hot can frequently stem from the body’s natural responses to daily activities and environmental conditions. Engaging in physical activity, such as exercise, causes muscles to generate heat as they work. The body then dissipates this excess heat through mechanisms like increased blood flow to the skin’s surface and sweating, which cools the body as sweat evaporates. Similarly, exposure to hot weather or a warm environment can directly increase both skin temperature and, if prolonged, core body temperature.
Hormonal fluctuations can also significantly influence thermoregulation, leading to feelings of warmth. During the menstrual cycle, a rise in progesterone levels after ovulation can cause a slight increase in core body temperature. Pregnancy also brings about an increase in body temperature due to increased blood volume and a higher metabolic rate supporting fetal development. Menopause is frequently associated with “hot flashes,” which are sudden, intense feelings of warmth primarily in the upper body, linked to changes in estrogen levels affecting the hypothalamus’s temperature control. Even emotional responses like stress or anxiety can trigger a temporary feeling of warmth as the body’s physiological state shifts.
Immune and Inflammatory Responses
A common reason for feeling hot is the presence of a fever, which signifies the body’s immune system actively responding to an internal challenge. A fever is a temporary elevation of the body’s temperature set point, usually above 100.4°F (38°C) for adults. This elevation is often triggered by substances called pyrogens, which can originate from outside the body (exogenous, like bacterial toxins) or be produced by the body’s own immune cells (endogenous, like cytokines). These pyrogens signal the hypothalamus to raise the body’s internal thermostat, leading to increased heat production and reduced heat loss.
Infections are the most frequent cause of fever, as the immune system raises body temperature to create an environment less favorable for pathogen growth and replication. Common examples include bacterial infections like strep throat or urinary tract infections, and viral infections such as the flu, common cold, or COVID-19. Beyond infections, systemic or localized inflammation can also cause the body to feel warm. Conditions like autoimmune diseases can trigger an inflammatory response that leads to a fever, as the immune system mistakenly attacks the body’s own tissues.
Other Medical Factors
While many instances of feeling hot are due to normal bodily functions or immune responses, certain other medical factors can also contribute to this sensation. Some medications, for example, can have side effects that interfere with the body’s thermoregulation. These include certain antidepressants, decongestants, and stimulants, which can directly affect how the body controls its temperature.
Thyroid disorders, specifically an overactive thyroid (hyperthyroidism), can lead to a persistent feeling of being warm. This condition accelerates the body’s metabolism, causing cells to produce more energy and heat. Insufficient fluid intake, or dehydration, also impairs the body’s ability to cool itself effectively. When dehydrated, the body has less fluid available for sweating, which is a primary mechanism for heat dissipation.
Knowing When to Seek Care
While feeling hot to the touch is often a temporary and harmless sensation, there are situations where it warrants medical attention. If a high temperature, typically 103°F (39.4°C) or higher in adults, is present, it is advisable to contact a healthcare provider. For infants younger than three months, any rectal temperature of 100.4°F (38°C) or higher requires immediate medical evaluation.
Other symptoms accompanying a hot sensation or fever should also prompt a medical consultation. These include:
Severe headache, stiff neck, rash, or unusual sensitivity to light
Confusion or difficulty breathing
Persistent vomiting or seizures
Signs of heat exhaustion or heatstroke, such as dizziness, nausea, rapid pulse, or hot, dry skin
It is important to consult a healthcare professional if the sensation of being hot is persistent, unexplained, causes significant discomfort, or if you belong to vulnerable populations such as infants, the elderly, or those with compromised immune systems.