Feeling unusually cold when sick is usually a sign that your body is cranking up its internal “thermostat” to fight an infection, which creates chills, shivers, and that cold, shaky feeling even if you actually have a fever.

What’s Actually Happening in Your Body

When you get an infection (like a cold or flu), your immune system releases chemicals called pyrogens that tell a part of your brain (the hypothalamus) to raise your internal temperature set point.

Suddenly, your current body temperature is “too low” compared with this new set point, so your brain makes you feel cold to push you to warm up (blankets, hot drinks, warmer clothes).

To reach that higher set point, your body:

  • Narrows blood vessels in your skin (vasoconstriction), sending more heat to your core and making your skin, hands, and feet feel cold.
  • Triggers shivering, where rapid muscle contractions generate extra heat but also make you feel shaky and chilled.

Why You Can Feel Cold and Have a Fever

It feels backwards: the thermometer says “fever,” but you’re grabbing more blankets. This happens in phases:

  1. Fever rising phase
    • The thermostat in your brain has been turned up.
    • You feel freezing, get goosebumps, and shiver as your body works to raise its temperature.
  1. Fever plateau
    • Your core temperature matches the new set point.
    • You might feel a bit warm but not as intensely chilled.
  1. Fever breaking
    • Your brain resets the set point back down toward normal.
    • Now you feel hot and start sweating as your body dumps the extra heat.

So that “I’m icy but also sweaty” sick feeling is basically your thermostat being temporarily reprogrammed while your body battles germs.

Other Reasons You Feel So Cold When Sick

Beyond the fever mechanics, several other factors make you feel extra chilly:

  • Less blood to the skin : Blood flow is prioritized to vital organs and the immune system, leaving your skin cooler.
  • Low energy and dehydration : Being tired, not eating much, and not drinking enough can make chills and weakness worse.
  • Room or clothing mismatch : When you’re sick, your ability to regulate temperature is more fragile, so a slightly cool room can feel freezing.

Infections that commonly cause chills and feeling cold include:

  • Colds and flu
  • Strep throat
  • Pneumonia or bronchitis
  • Urinary tract or kidney infections

When Feeling Cold While Sick Is a Red Flag

Most of the time, feeling cold and shivery is a normal part of having a fever and fighting off a routine infection.

However, you should seek urgent medical care if chills or feeling freezing come with:

  • Very high fever (for adults, around 103°F/39.4°C or higher, or any fever that worries you)
  • Confusion, trouble staying awake, or severe headache
  • Chest pain, trouble breathing, or blue lips/fingertips
  • Very fast heart rate, blotchy or rapidly spreading rash, or severe pain
  • Burning when you pee, flank pain, or blood in urine (possible serious UTI/kidney infection)

If you have underlying health conditions (heart disease, lung disease, immune problems) or are pregnant, older, or caring for a very young child, it is safer to contact a doctor early when intense chills or feeling very cold show up with illness.

Simple Ways to Feel Less Cold When Sick

These home-care steps can ease that “why am I so cold when sick?” feeling while your body does the work:

  • Layer up with light, breathable clothing and a blanket so you can adjust easily if you suddenly feel hot.
  • Drink warm fluids (broth, tea, warm water) to support hydration and comfort.
  • Rest in a comfortably warm (not hot) room to avoid overcooling or overheating.
  • Use fever-reducing medicines such as acetaminophen or ibuprofen only as directed by a healthcare professional or package instructions.

If you’re ever unsure whether your symptoms are “normal sick” or something serious, treating it as worth a call or visit to a medical professional is always the safer choice.

Bottom note: Information gathered from public forums or data available on the internet and portrayed here.