Fever With Chills: Why the Body Shivers as Temperature Rises

By Your Health Magazine Health Information Team

Fever chills are episodes of feeling cold and shivering while the body’s temperature is rising. They happen because the brain temporarily raises the body’s temperature target. Until the body reaches that higher target, the person may feel unusually cold—even though their measured temperature is already elevated.

Why Does a Fever Make You Shiver?

An area of the brain called the hypothalamus acts like the body’s thermostat. During many infections and inflammatory responses, immune signals cause the hypothalamus to set a higher target temperature.

The body then behaves as though it is too cold compared with that new target. Blood vessels near the skin narrow to reduce heat loss, which can make the skin look pale and the hands or feet feel cold. Muscles rapidly contract and relax, producing the shaking known as shivering. These contractions generate heat and help raise the core temperature.

Once the body reaches its new temperature target, the chills may stop. Later, when the thermostat resets closer to normal, the person may feel hot, sweat and remove blankets as the body releases excess heat.

Fever stage	What the person may notice	What the body is doing
Temperature rising	Chills, shivering, cold skin or goose bumps	Producing and conserving heat
Temperature elevated	Warm skin, fatigue, headache or body aches	Maintaining the higher temperature target
Temperature falling	Feeling hot or sweating	Releasing heat as the target returns toward normal

The National Library of Medicine offers more detail about how chills develop and what may cause them.

What Causes Fever With Chills?

Infections are the most common cause. Fever and chills can occur with:

Influenza and other respiratory viruses
COVID-19 or respiratory syncytial virus
Pneumonia
Strep throat or other bacterial throat infections
Urinary tract or kidney infections
Gastrointestinal infections
Skin infections

Influenza often begins suddenly with fever or chills, muscle aches, headache, fatigue and respiratory symptoms. The MedlinePlus influenza overview explains common flu symptoms, diagnosis and treatment considerations.

Less commonly, fever and chills may be associated with inflammatory or autoimmune conditions, certain medicines, reactions following some vaccinations or infections acquired during travel. Recurrent shaking chills, especially after international travel, should be discussed promptly with a healthcare professional.

Chills Do Not Always Mean There Is a Fever

A person can shiver after exposure to cold air or water without having a fever. Anxiety, intense emotion and other physical responses may also produce trembling or goose bumps. Conversely, someone can have a fever without noticeable chills.

The only reliable way to determine whether a fever is present is to use a digital thermometer. A reading of 100.4°F (38°C) or higher is commonly treated as a fever, although the interpretation can vary with age, time of day and whether the temperature was taken orally, rectally, under the arm, in the ear or across the forehead.

Record both the number and the measurement method when contacting a healthcare professional. For additional context about normal readings and unit conversion, see this guide to understanding body temperature in Celsius and Fahrenheit.

What to Do at Home

For a mild illness without warning signs, the main goal is comfort rather than forcing the temperature back to a specific number.

Check the temperature. Do not rely only on touching the forehead or judging how cold the person feels.
Encourage fluids. Fever and sweating can contribute to dehydration. Water, oral rehydration drinks, broth and other tolerated fluids may help.
Allow rest. Reduce strenuous activity while fever and significant symptoms are present.
Use light layers. A light blanket may help during chills, but avoid heavy clothing or multiple blankets that trap excessive heat.
Avoid extreme cooling. Ice baths, very cold water and rubbing alcohol can trigger more shivering and may be unsafe.

Over-the-counter fever reducers may ease discomfort when they are appropriate for the person, but follow the product label and avoid combining products containing the same active ingredient. Ask a physician or pharmacist before giving medicine to a young child or to someone who is pregnant, takes other medications, or has kidney disease, liver disease, ulcers or another significant medical condition. Do not give aspirin to children or teenagers unless specifically directed by a healthcare professional.

When to Seek Care

Call 911 or seek emergency care when fever and chills occur with trouble breathing, chest pain, severe confusion, difficulty waking, a seizure, blue lips, a stiff neck with a severe headache, a rapidly spreading purple or bruise-like rash, or signs of severe dehydration.

Fever, intense shivering or feeling very cold can also occur with sepsis, a life-threatening response to infection. Confusion, clammy skin, shortness of breath, extreme discomfort, or a fast heart rate alongside these symptoms requires immediate evaluation. Review the CDC’s signs and symptoms of sepsis for additional guidance.

Contact a physician, pediatrician or urgent care service promptly if:

An infant younger than 3 months has a rectal temperature of 100.4°F (38°C) or higher.
An adult’s temperature reaches 103°F (39.4°C) or higher.
A child’s temperature repeatedly rises above 104°F (40°C).
The fever persists, returns after improving or is accompanied by worsening symptoms.
There is repeated vomiting, pain with urination, significant abdominal pain, a worsening cough or difficulty drinking fluids.
The person has a weakened immune system, recently had surgery, or has another condition that increases the risk of serious infection.

Parents can find age-specific warning signs in the American Academy of Pediatrics guidance on when to call a pediatrician about a child’s fever. When uncertain, consider the person’s breathing, alertness, hydration and overall behavior—not just the thermometer reading.