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Medically reviewed guide · Last updated: 23 July 2026 · Reading time: approx. 9 min.
Chills: harmless or a warning sign?
At a glance
What is it?Involuntary, intense muscle shivering with a feeling of cold — this is how the body produces heat, usually as fever rises rapidly
Usually harmless?Often yes — with flu-like infections, chills accompany the fever and subside as it fades
Common triggersViral and bacterial infections (influenza, urinary tract infection, pneumonia), less often cooling down without fever
Warning signsChills with high fever, feeling severely unwell, confusion or rapid breathing — suspected blood poisoning (sepsis)
Key distinctionChills with fever (infection) versus simply feeling cold without fever (cooling down, circulation)
What to doMeasure your temperature, assess how unwell you feel, check for red flags — see a doctor if in doubt
Keep an eye on fever and chills
Record your temperature, chills episodes and accompanying symptoms in brite — a clear overview that is worth its weight in gold at your doctor's appointment. Free of charge.
Chills are an involuntary, often violent shivering of the muscles, accompanied by a strong feeling of cold — even though the body is actually raising its temperature. Your teeth chatter, your arms and legs tremble, and sometimes your whole body shakes. Such an episode typically lasts a few minutes and, with an infection, often recurs several times.
Behind the shivering lies a clever mechanism: as fever rises rapidly, the body raises its internal "set point". To reach the new, higher target temperature quickly, the shivering muscles generate extra heat — much as physical exertion during exercise warms the body. That is why you feel cold at the onset of a fever, even though your temperature is already climbing.
The key point first
Chills are usually a companion of fever and are normal with harmless infections. What matters is how severely ill you feel and whether warning signs of blood poisoning (sepsis) are also present — in that case every minute counts.
2. With fever or without?
One question is especially important for assessing the situation: Do you have a fever as well — or are you just feeling cold? Because chills and simply feeling cold feel similar, but have different causes.
Chills with fever: the classic case. The body is heating up to fight an infection. The shivering accompanies the rise in fever and eases once the target temperature is reached. You can find out more about temperature under Fever.
Feeling cold without fever: shivering from the cold after cooling down, with circulatory weakness, low blood sugar or fear and agitation. Here the temperature does not rise — it is a direct reaction to cold or stress and usually harmless.
What matters is this: very violent chills with high fever and a severe feeling of illness should always be taken seriously. They can be the first sign of a bacterial infection spreading through the body — right up to blood poisoning (sepsis). More on this in the chapter "When to see a doctor".
3. Causes & triggers
In the vast majority of cases, an infection is behind the chills. The body responds to pathogens with fever — and chills are the tool for driving the temperature up quickly.
Viral infections: above all true influenza (flu), which often begins with sudden, powerful chills, as well as flu-like infections and gastrointestinal infections.
Urinary tract infections: if a bladder infection ascends to the kidney (pyelonephritis), fever with violent chills is common — see Urinary tract infection.
Pneumonia: a case of pneumonia classically comes with high fever, chills, coughing and shortness of breath.
Other bacterial infections: such as wound infections, tonsillitis or inflammation of the bile ducts.
Travel-related illnesses: after a stay in the tropics, recurring chills can point to malaria — always have this clarified by a doctor promptly.
Non-infectious triggers: severe cooling down, circulatory reactions, and more rarely certain medications or blood transfusions.
The link to an infection that is starting up can often be recognised yourself. What matters is keeping an eye on the fever and the course of the illness.
4. Measuring fever correctly
Because chills are almost always linked to fever, measuring your temperature is the most important first step. It shows whether you really have a fever and how high it is — both help with the assessment.
Measuring correctly: the most accurate reading is taken rectally (in the bottom). Ear and forehead thermometers are convenient, but a little less accurate.
Interpreting the values: from about 38.0 °C onwards it is called a fever, from 39.0 °C a high fever. Below 38 °C there is a raised temperature.
Mind the timing: during the chills the reading may still be low, because the fever is only just rising — measure again after a short while.
Making notes: record your temperature, the time, chills episodes and accompanying symptoms — ideal for the conversation with your doctor.
Alongside the mere number, pay particular attention to your general condition: a child or adult who is still responsive and reasonably alert despite a fever is to be assessed differently from someone with a severe feeling of illness, confusion or rapid breathing.
Your fever log always with you
With brite you record your temperature, chills and accompanying symptoms — the best basis for helping the practice get to the bottom of the cause quickly.
Chills with a simple infection usually subside on their own. But there are situations in which you need medical help promptly — and warning signs where every minute counts.
You should seek medical advice promptly if high fever with chills lasts longer than two to three days, keeps recurring, is joined by pain when passing water or flank pain, or if you develop chills after a trip to the tropics. In infants, older people or those with a weakened immune system, fever with chills should also be clarified sooner.
Call the emergency number 112 immediately
If chills and high fever occur together with a severe feeling of illness, confusion or drowsiness, very rapid breathing or a rapid pulse, or mottled, pale or cold skin. This can point to blood poisoning (sepsis) — a life-threatening emergency that requires immediate action.
6. Diagnosis
To find the cause of the chills, the practice focuses on the search for the source of infection. A precise account and the measured values are important.
Examination
What it shows
Medical history & temperature reading
Course, height of the fever, accompanying symptoms, travel, pre-existing conditions
Physical examination
Lungs, throat, kidney area, skin — searching for the source of infection
Blood test
Inflammatory markers (CRP, blood count), signs of a bacterial infection
Urine test
Detects a urinary tract infection as the source of the fever
X-ray / ultrasound
Makes pneumonia or other foci visible, if needed
Table scrollable to the right
The more precisely you can describe the course of the fever, the chills episodes and the accompanying symptoms, the faster the source can be narrowed down. A well-kept log makes the assessment considerably easier.
7. What you can do yourself
Allow warmth: during the chills, a blanket and a calm environment help. When the fever then rises and you feel hot, do not wrap up too warmly.
Drink plenty: fever and sweating draw fluid from the body — water, tea or broth make up for it.
Rest: bed rest and taking it easy give the body the strength to fight the infection.
Reduce fever if needed: fever-reducing medicines such as Paracetamol or Ibuprofen can help with a severe feeling of illness — mind the dosage and check with a professional if in doubt.
Watch for warning signs: if your condition worsens and confusion, shortness of breath or a very rapid pulse are added, do not hesitate to call the emergency services.
Keep the course of the fever under control
brite helps you document your temperature, chills and medicines over time — free of charge and ad-free.
With fever and chills, the course is decisive: how high does the temperature rise, how often do the chills return, which symptoms are added? Recording this means you spot deterioration early and give the practice the crucial clues. brite makes that easy.
Health history — document your temperature, chills episodes and accompanying symptoms over time and bring an overview to your appointment. Track your history
Intake reminder — for fever-reducing medicines or a prescribed course of antibiotics, brite reliably reminds you to take them correctly. Set up a reminder
Interaction check — checks whether fever-reducing medicines such as Paracetamol or Ibuprofen are compatible with your other medications. Check now
Digital medication plan — all your medicines clearly in one place for your GP and the hospital. To the medication plan
Usually not — with a flu-like infection, chills accompany the fever and subside as it fades. They become dangerous when high fever and violent chills combine with a severe feeling of illness, confusion, very rapid breathing or cold, mottled skin. In that case there is a suspicion of blood poisoning and you should call the emergency number 112 immediately.
As the fever rises, the body sets its internal temperature set point higher. To reach this higher target temperature quickly, the shivering muscles generate extra heat — much as during exercise. That is why you feel cold and shiver, even though the temperature is already climbing.
Chills are a violent, involuntary shivering of the muscles that usually accompanies a rise in fever. Simply feeling cold is a direct reaction to cold or cooling down, without the body temperature rising. The most important difference is therefore whether a fever is present — which is why measuring your temperature is always worthwhile.
Yes. Intense shivering from the cold can also occur without a fever — for example after cooling down, with circulatory weakness, low blood sugar or strong agitation. This is usually harmless. But if the chills keep coming back or you feel distinctly ill, you should measure your temperature and have the cause clarified.
The most accurate reading is taken rectally, in the bottom. Ear and forehead thermometers are convenient, but a little less accurate. From about 38.0 °C onwards it is called a fever, from 39.0 °C a high fever. During the chills the reading may still be low, because the fever is only just rising — so measure again after a short while.
Warning signs are high fever or below-normal temperature with violent chills, a severe feeling of illness, confusion or drowsiness, very rapid breathing, a rapid pulse, and pale, cold or mottled skin. Sepsis is a life-threatening emergency — with these signs, call the emergency number 112 immediately.
Have it clarified if high fever with chills lasts longer than two to three days, keeps recurring, is joined by pain when passing water or flank pain, or if you develop chills after a trip to the tropics. In infants, older people or those with a weakened immune system, as well as with warning signs of sepsis, you should act sooner or immediately, respectively.
During an episode, rest and a warming blanket help. Enough fluids and taking it easy are important. With a severe feeling of illness, fever-reducing medicines such as Paracetamol or Ibuprofen can be sensible — mind the dosage. If a bacterial infection is behind it, a doctor-prescribed course of antibiotics may be necessary.
Recurring chills with fever after a stay in tropical regions can point to malaria. This illness must be recognised and treated quickly. So see a doctor promptly and be sure to mention your trip, even if it was some weeks ago.
This article is for general information and does not replace medical advice, diagnosis or treatment. With chills and high fever together with a severe feeling of illness, confusion, very rapid breathing or cold, mottled skin, please call the emergency number 112 without delay (suspected blood poisoning).
