Chills
Feeling cold with shivering, often accompanying fever or illness.
TL;DR
Chills are the body raising its temperature set-point, usually from infection. The rigor itself is not dangerous — the cause can be.
Overview
A chill is shivering thermogenesis: the hypothalamus has raised its target temperature, and until core temperature catches up you feel cold and shake, even while your temperature is climbing. Pyrogens from infection are the usual trigger, but drugs, transfusion reactions, and rarely malignancy do the same. A true rigor — uncontrollable, teeth-chattering shaking lasting several minutes — carries more weight clinically than the height of the fever, because it correlates with bacteraemia. Chills without fever occur in hypothyroidism, anaemia, and hypoglycaemia, and point to a different set of causes.
Common Symptoms
- •Shivering and teeth chattering
- •Feeling cold despite a rising temperature
- •Goosebumps and pallor
- •Muscle aching
- •Sweating as the fever breaks
Common Causes
- •Viral or bacterial infection
- •Urinary tract infection or pyelonephritis
- •Pneumonia
- •Influenza and COVID-19
- •Post-vaccination immune response
- •Drug or transfusion reaction
Root Causes
Pyrogen-driven elevation of the hypothalamic set-point, most often from bacterial or viral infection; also drug reactions, post-vaccination immune activation, and thermoregulatory failure.
How It's Diagnosed
Diagnostic Markers
- Temperature, heart rate, respiratory rate and blood pressure
- Full blood count and CRP
- Urine dipstick and culture
- Blood cultures if rigors are present
- Chest imaging if cough or breathlessness
When to See a Doctor
Seek urgent care for rigors with confusion, breathlessness, a rash that does not blanch, severe headache with neck stiffness, or chills in anyone immunosuppressed, pregnant, or recently in a malaria-endemic area.
Supplements Studied For This
Diet & Lifestyle
Suggested Pattern
No dietary intervention treats chills. Maintain fluids and simple, easily tolerated food during a febrile illness.
Eat more
- Water and oral rehydration solution
- Broths and soups
- Easily digestible carbohydrates
Avoid
- Alcohol
- Heavy fatty meals during an acute fever
Supporting Research
Zinc for the common cold
Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data
Vitamin C for preventing and treating the common cold
Black elderberry (Sambucus nigra) supplementation effectively treats upper respiratory symptoms: A meta-analysis of randomized, controlled clinical trials
Echinacea for treating the common cold: a randomized trial
Frequently Asked Questions
Who It Affects
Chills accompany the majority of febrile illnesses; rigors are reported in roughly 10-20% of bacteraemic episodes.
Any age; more concerning in infants, over-65s, and immunosuppressed people.
Quick Facts
- •A true rigor raises the likelihood of bacteraemia
- •Chills without any fever suggest a non-infectious cause
- •Piling on blankets does not shorten the chill phase
- •Temperature height correlates poorly with severity
Lifestyle Tips
- •Treat the underlying cause, not the shivering
- •Paracetamol or ibuprofen for comfort — neither shortens the illness
- •Keep fluid intake up; fever increases insensible losses
- •Rest and monitor rather than layering heavy blankets
- •Track temperature twice daily rather than obsessively
My Notes
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This information is for educational purposes only. Always consult a healthcare professional before starting any supplement regimen.