Why Do Infants With HED Get Unexplained Fevers?

For infants with Hypohidrotic Ectodermal Dysplasia (HED), unexplained high temperatures are often the result of an inability to sweat. Sweating is the body’s natural cooling system. Because babies with HED are born with significantly reduced or completely missing sweat glands, their bodies cannot release heat when they get too warm ^[1]. Without this built-in cooling mechanism, their internal body temperature can rise rapidly and dangerously in situations that would be completely normal for other infants ^[2].

The “Fever of Unknown Origin”

In the first few months of life, before a diagnosis of HED is made, these temperature spikes are frequently mistaken for infections and labeled by doctors as a “fever of unknown origin” ^[2]. When a baby gets hot, they cannot produce the sweat that would normally evaporate and cool their skin ^[3]. Instead, the heat stays trapped inside the body, leading to a dangerously high core temperature. Recognizing this pattern of recurrent, unexplained temperature spikes is often a critical step in diagnosing HED early and preventing life-threatening overheating, known as hyperthermia ^[4][5]. Hyperthermia is a dangerous rise in body temperature caused by a failure of the body’s natural heat-regulating mechanisms.

Common Triggers for Overheating

Because infants cannot regulate their own environment, they are incredibly sensitive to external heat sources. For a baby with HED, an inability to tolerate heat means even mild triggers can cause core temperatures to spike ^[1][2]. Everyday triggers that can cause a dangerous temperature rise include:

• Warm environments: A slightly warm bedroom, a hot summer day, or sitting in a warm car seat.
• Over-bundling: Wearing too many layers of clothing, being wrapped in heavy blankets, or being swaddled.
• Physical exertion and emotion: Extended periods of crying, physical therapy, or vigorous feeding can generate internal body heat that the baby cannot easily release.
• Skin-to-skin contact: Prolonged body heat transfer from a parent or caregiver without adequate airflow.

Warning Signs of Hyperthermia

Parents and caregivers must be vigilant in monitoring a baby with HED. Because the baby will not look sweaty, you must look for other signs of distress ^[2]. Always use a reliable thermometer (rectal is generally most accurate for infants) to confirm their temperature, as babies with HED can quickly spike dangerously high temperatures, sometimes exceeding 102°F or 104°F (38.9°C to 40°C) ^[2][4]. Warning signs that a baby’s temperature is rising too high include:

• Skin that feels unusually hot and completely dry to the touch (rather than clammy or sweaty)
• Extreme fussiness, irritability, or inconsolable crying
• Flushed, red skin or, conversely, pale and mottled skin
• Lethargy, unusual sleepiness, or lack of responsiveness
• Rapid breathing or an abnormally fast heartbeat

If you suspect your baby is overheating, it is vital to physically cool them down immediately. Effective strategies include moving to an air-conditioned room, removing excess clothing, or applying cool, damp washcloths to their skin. Never use ice baths or freezing water, as extreme cold can cause shivering (which generates more internal body heat) or send the baby into shock. If your baby is conscious and it is age-appropriate, you can also offer cool fluids.

Standard fever-reducing medications (like acetaminophen or ibuprofen) are designed to lower a fever caused by an illness or infection; they do not work for environmental overheating. Managing hyperthermia in HED relies entirely on early identification and physical, environmental cooling ^[2][6].

Emergency Warning: If your infant is unresponsive, severely lethargic, or if physical cooling does not rapidly lower their temperature, seek emergency medical care immediately.