Chills

Chills are feelings of coldness accompanied by shivering, which occur when your body tries to raise its temperature. While often associated with fever and infection, chills can have various causes ranging from minor viral illnesses to serious conditions like sepsis. The severity and pattern of chills, along with accompanying symptoms, help determine their significance.

Quick Facts

  • Body's warming response
  • Often precede fever
  • Common with infections
  • Can be serious sign
  • Various causes

⚠️ Seek Emergency Care Immediately If Chills Occur With:

  • High fever (over 103°F/39.4°C) that doesn't respond to medication
  • Difficulty breathing or shortness of breath
  • Confusion, disorientation, or altered mental state
  • Severe headache with stiff neck
  • Rapid heart rate or chest pain
  • Blue lips, fingernails, or skin (cyanosis)
  • Severe abdominal pain
  • Signs of dehydration (dizziness, dry mouth, little urination)
  • Rash that doesn't fade when pressed
  • Persistent vomiting
  • Recent surgery or medical procedure
  • Weakened immune system with fever

These symptoms may indicate sepsis, meningitis, pneumonia, or other serious infections requiring immediate treatment.

Understanding Chills

Chills occur when your muscles rapidly contract and relax to generate heat. This involuntary response is triggered when your body's temperature set point rises, often due to infection or illness. The hypothalamus, your body's thermostat, senses that your actual temperature is lower than the new set point and initiates shivering to warm you up.

The relationship between chills and fever is important to understand. Chills often occur at the beginning of a fever as your body temperature rises. Once your temperature reaches the new set point, the chills typically stop. When the fever breaks and your temperature set point returns to normal, you may experience sweating as your body cools down.

Not all chills are accompanied by fever. Cold exposure, emotional responses, low blood sugar, and certain medications can also trigger chills. The pattern, severity, and associated symptoms help distinguish between different causes and determine the appropriate response.

Types of Chills

Mild Chills

  • Light shivering
  • Feeling cold
  • Goosebumps
  • Teeth chattering
  • Can control somewhat
  • Common with mild illness

Severe Chills (Rigors)

  • Violent shaking
  • Uncontrollable shivering
  • Whole body involvement
  • Bed shaking intensity
  • Often with high fever
  • Suggests serious infection

Intermittent Chills

  • Come and go pattern
  • Cyclical occurrence
  • May follow fever pattern
  • Common in malaria
  • Some bacterial infections
  • Medication reactions

Continuous Chills

  • Persistent shivering
  • Doesn't resolve
  • Despite warming
  • May indicate sepsis
  • Severe infections
  • Medical emergency

Common Causes

Infectious Causes

  • Influenza (Flu): Classic cause of chills with sudden high fever
  • Common cold: Mild chills, usually without high fever
  • Pneumonia: Chills with cough, chest pain, breathing difficulty
  • Urinary tract infection: Chills with urinary symptoms
  • Strep throat: Severe sore throat with chills
  • Gastroenteritis: Stomach bug with chills, nausea, diarrhea
  • Sepsis: Life-threatening response to infection
  • Meningitis: Severe headache, stiff neck, chills
  • COVID-19: Chills with fever, cough, loss of taste/smell
  • Malaria: Cyclical chills and fever if traveled to endemic areas

Non-Infectious Causes

  • Medication reactions: Antibiotics, chemotherapy drugs
  • Blood transfusion reaction: Immune response to transfusion
  • Inflammatory conditions: Rheumatoid arthritis flares
  • Cancer: Lymphoma, leukemia
  • Thyroid storm: Severe hyperthyroidism
  • Drug withdrawal: Alcohol, opioids, benzodiazepines
  • Kidney stones: When causing infection or inflammation
  • Heat exhaustion: Paradoxical chills with overheating

Other Causes

  • Exposure to cold: Normal response to cold environment
  • Hypothermia: Dangerous drop in body temperature
  • Emotional response: Fear, anxiety, excitement
  • Low blood sugar: In diabetes or fasting
  • Anemia: Severe cases can cause chills
  • Dehydration: Affects temperature regulation
  • Post-surgical: Common after anesthesia

Chills and Fever Patterns

Continuous Pattern

  • Fever stays high
  • Minimal fluctuation
  • Chills at onset
  • Pneumonia typical
  • Typhoid fever
  • Drug reactions

Intermittent Pattern

  • Fever spikes and drops
  • Normal between spikes
  • Chills with each spike
  • Abscesses
  • Malaria
  • Septicemia

Remittent Pattern

  • Fever fluctuates
  • Never reaches normal
  • Chills with rises
  • Most infections
  • Viral illnesses
  • Endocarditis

Relapsing Pattern

  • Fever-free periods
  • Days between episodes
  • Chills herald return
  • Hodgkin lymphoma
  • Borrelia infections
  • Malaria variants

Associated Symptoms

Chills rarely occur alone and are often accompanied by other symptoms that help identify the cause:

  • Fever: Most common association, indicates infection or inflammation
  • Headache: Common with systemic infections
  • Fatigue: Body fighting infection
  • Body aches: Muscle and joint pain with viral infections
  • Sweating: Alternating with chills as fever breaks
  • Nausea and vomiting: Gastroenteritis or severe infection
  • Cough: Respiratory infections
  • Sore throat: Upper respiratory infections
  • Urinary symptoms: Burning, frequency with UTI
  • Abdominal pain: Appendicitis, diverticulitis
  • Skin changes: Rash, redness, warmth
  • Confusion: Severe infection or sepsis
  • Rapid heartbeat: Body's response to fever
  • Shortness of breath: Pneumonia or sepsis

When Chills Indicate Serious Illness

Signs of Sepsis

  • Severe, uncontrollable chills
  • High fever or abnormally low temperature
  • Rapid breathing and heart rate
  • Confusion or disorientation
  • Extreme pain or discomfort
  • Clammy or sweaty skin
  • Recent infection or surgery

Signs of Meningitis

  • Severe headache with chills
  • Stiff neck
  • High fever
  • Sensitivity to light
  • Rash that doesn't fade
  • Nausea and vomiting
  • Confusion

Other Serious Conditions

  • Blood clot with infection
  • Severe pneumonia
  • Kidney infection spreading
  • Endocarditis (heart valve infection)
  • Bone or joint infections
  • Abdominal infections

Diagnosis and Evaluation

Medical History

  • Duration and pattern of chills
  • Fever measurements
  • Associated symptoms
  • Recent travel
  • Sick contacts
  • Medications
  • Immune system status
  • Recent procedures

Physical Examination

  • Temperature measurement
  • Vital signs (pulse, blood pressure, breathing)
  • Skin examination
  • Lymph node check
  • Chest examination
  • Abdominal exam
  • Neurological assessment

Diagnostic Tests

  • Blood tests: Complete blood count, cultures
  • Urine tests: Urinalysis and culture
  • Chest X-ray: If respiratory symptoms
  • Blood cultures: To identify bacteria
  • Inflammatory markers: CRP, ESR
  • Specific tests: Based on suspected cause
  • Imaging: CT scan if abscess suspected

Treatment Approaches

Immediate Care

  • Rest in warm environment
  • Layer blankets
  • Warm fluids
  • Avoid alcohol
  • Monitor temperature
  • Stay hydrated

Fever Management

  • Acetaminophen
  • Ibuprofen
  • Cool compresses after chills
  • Light clothing when fever breaks
  • Avoid over-bundling
  • Room temperature water

Medical Treatment

  • Antibiotics if bacterial
  • Antivirals if indicated
  • IV fluids if dehydrated
  • Hospital care if severe
  • Treat underlying cause
  • Supportive care

Home Care

  • Bed rest
  • Increase fluid intake
  • Nutritious foods
  • Avoid spreading illness
  • Monitor symptoms
  • Follow up as directed

Prevention Strategies

  • Vaccination: Flu shot, pneumonia vaccine, COVID-19 vaccine
  • Hand hygiene: Regular washing, especially during illness season
  • Avoid sick contacts: Stay away from people with infections
  • Immune support: Good nutrition, adequate sleep, exercise
  • Travel precautions: Malaria prophylaxis if needed
  • Food safety: Proper cooking and storage
  • Wound care: Clean and cover cuts properly
  • Manage chronic conditions: Control diabetes, take medications
  • Stay warm: Dress appropriately for weather
  • Avoid mosquitoes: In malaria-endemic areas
  • Safe water: When traveling
  • Prompt treatment: Address infections early

When to See a Doctor

See a Doctor Within 24 Hours For:

  • Chills with fever over 103°F (39.4°C)
  • Chills lasting more than an hour
  • Recurring chills over several days
  • Chills with concerning symptoms
  • No improvement after 3 days
  • Worsening symptoms
  • Chronic illness or weak immune system
  • Recent travel to tropical areas
  • Known exposure to serious infection

Call 911 or Seek Emergency Care For:

  • Difficulty breathing
  • Confusion or altered mental state
  • Severe headache with stiff neck
  • Blue lips or fingernails
  • Rapid heart rate with dizziness
  • Signs of severe dehydration
  • Uncontrollable shaking
  • Temperature over 105°F (40.5°C)

Related Conditions

Fever

Chills often precede or accompany fever as the body raises its temperature.

Influenza

Classic cause of sudden chills with high fever and body aches.

Pneumonia

Lung infection causing chills, fever, cough, and breathing difficulty.

Fatigue

Often accompanies chills as the body fights infection.