What Makes You Feel Colder When Your Body Is Hotter?
It’s actually a normal physiological response. As soon as your brain shifts its internal thermostat to a higher set point to fight off an infection, the rest of your body goes to work trying to generate extra heat to meet that higher temperature goal. Suddenly, you’re technically below your new “ideal” core temperature, so you feel cold.
Feeling chilled then prompts you to start shivering and even shaking “as your body tries to generate heat to raise your temperature by making your muscles contract,” explains Nate Favini, MD, a primary care specialist based in San Francisco.
How Long Do Fever and Chills Last in Adults?
The length of a fever — and any accompanying chills — can vary significantly depending on its cause. “In some cases with a mild viral illness, a fever can last for a day, or it can last for weeks to months with systemic infections,” says Dr. Adalja.
The best thing to do is play detective to determine the source of your fever based on other signs and symptoms of your illness, he says. Possible causes abound, including colds and the flu, bronchitis, pneumonia, appendicitis, gastroenteritis, mononucleosis, ear infections, sinus infections, and urinary tract infections (UTIs).
While fevers are usually caused by viral or bacterial infections, other conditions that can spike your temperature include certain inflammatory disorders, such as lupus, rheumatoid arthritis, and Crohn’s disease, as well as cancer and blood clots (such as deep vein thrombosis). Even certain medications, such as penicillin, sulfa drugs, and antipsychotics, can trigger a fever, as can some illegal drugs, such as cocaine, according to the Merck Manual.
What Should You Do When You Have the Chills and Fever?
Fevers and chills in adults that go hand-in-hand generally resolve within a few days, notes the Mayo Clinic. If your temperature is mildly elevated — between 100 degrees F and 102 degrees F — and you have no other worrisome symptoms (see below), the best course of action is to simply rest and drink plenty of fluids to keep from becoming dehydrated.
However, even though you feel cold on the outside, you should keep clothing and blankets light to prevent overheating, because inside your body is very hot, according to UPMC HealthBeat.
When Should I Call the Doctor?
If your temperature hits 103 degrees F, you should contact your doctor, per the Mayo Clinic. And according to the Merck Manual’s guidance, you should also consult your doctor if:
- You have a serious medical condition that could make a moderate fever more dangerous, such as a heart or lung disorder
- Your fever lasts more than 24 to 48 hours
Seek medical help immediately if anything unusual or alarming accompanies the fever and chills, such as any of these symptoms:
- A change in mental function, such as confusion
- A headache, stiff neck, or both
- Flat, small, purplish red spots on the skin, which indicate bleeding under the skin
- Low blood pressure
- Rapid heart rate or rapid breathing
- Shortness of breath
- Recent travel to an area where a serious infectious disease such as malaria is common
- Recent use of drugs that suppress the immune system (immunosuppressants)
What Medication, if Any, Should I Take?
Because fever helps the body defend against infection and because a moderate fever itself is not dangerous, the Mayo Clinic advises that it’s often best for otherwise healthy adults to let a fever run its course.
If you’re uncomfortable, however, consider taking an over-the-counter fever reducer like acetaminophen (Tylenol) or nonsteroidal anti-inflammatory drugs (NSAID) like aspirin, ibuprofen (Advil), or Aleve (naproxen). Follow the instructions on the label precisely for proper dosage.
Also be careful not to take more than one medication containing acetaminophen, which is a common ingredient in many over-the-counter medications, including cough and cold remedies. Acetaminophen can cause serious harm to the liver if you take too much.