Chills are involuntary, rapid muscle contractions your body uses to generate heat. They can range from a mild shivery feeling to intense, bed-shaking episodes called rigors, where your teeth chatter and your whole body trembles. Most people associate chills with being sick, but they can also be triggered by cold environments, emotional experiences, low blood sugar, surgery recovery, and even panic attacks.
How Your Body Creates Chills
Chills start in a small region of the brain called the hypothalamus, which acts as your body’s thermostat. When the hypothalamus detects that your core temperature is too low, or that it needs to be higher (as during an infection), it activates a motor center that triggers rapid, involuntary skeletal muscle contractions. That’s the shivering you feel. At the same time, your adrenal glands release stress hormones that ramp up your metabolic rate, and your thyroid kicks in to produce additional heat.
You’ll also notice goosebumps during chills. That’s piloerection, a leftover reflex from when our ancestors had enough body hair for it to trap an insulating layer of air. Your body may also instinctively curl up to reduce the amount of skin exposed to the air.
Chills During Fever and Infection
The most common reason for chills is that your body is fighting an infection. When bacteria or viruses enter your system, your immune cells release signaling molecules that travel to the hypothalamus and raise its temperature set-point. Think of it like someone turning your thermostat from 98.6°F up to 102°F. Your body now “believes” it should be hotter than it currently is, so it treats your normal temperature as too cold and triggers shivering to close the gap.
This is why you can feel freezing and pile on blankets even while your skin is warm to the touch and a thermometer reads well above normal. A fever is generally defined as a temperature of 100.4°F (38°C) or higher. Adults with fevers above 103°F (39.4°C) typically look and feel noticeably ill.
The character of chills can hint at what’s going on. A general sense of feeling chilly is common with almost any fever and isn’t very specific. But an abrupt onset of fever with one or two intense, teeth-chattering rigors suggests an acute bacterial infection, such as pneumonia. Fevers that swing widely throughout the day, producing alternating chills and sweats, are associated with abscesses, kidney infections, and sometimes lymphoma or tuberculosis.
Chills Without a Fever
Not every episode of chills means you’re running a temperature. Several conditions can produce shivering on their own:
- Cold exposure. In mild hypothermia, when core temperature drops to 90–95°F, shivering is one of the earliest responses. If the body continues cooling below roughly 86–90°F, shivering actually stops, which is a dangerous sign.
- Low blood sugar. People with diabetes may experience chills when blood sugar drops too low, as the body releases stress hormones in response.
- Menopause. Hot flashes and night sweats can be followed by chills as the body rapidly adjusts its temperature.
- Panic attacks. The surge of adrenaline during a panic attack can trigger trembling and shivering that feels identical to cold-related chills.
- Psychological trauma. A car accident, near-miss, or PTSD flashback can produce a rush of adrenaline intense enough to make your whole body shake.
- Hangovers and drug withdrawal. Both disrupt your body’s temperature regulation and can cause chills alongside nausea and fatigue.
- Post-surgical recovery. As many as two in three people experience chills after receiving general anesthesia. Anesthesia suppresses your body’s normal temperature-control reflexes during surgery, and when those reflexes return in recovery, your brain suddenly registers the temperature drop and triggers intense shivering to compensate.
Night Sweats and Chills
Waking up drenched in sweat and then feeling chilled is a specific pattern worth understanding on its own. Night sweats are an exaggeration of the body’s normal overnight temperature fluctuations. Any condition that causes a fever can produce them, but recurring, drenching night sweats are particularly associated with tuberculosis, lymphoma, certain bacterial infections, and poorly controlled diabetes. Menopause is another extremely common cause. If night sweats happen repeatedly over weeks and you can’t explain them by a warm room or heavy blankets, it’s worth investigating.
Emotional Chills (Frisson)
You’ve probably felt a wave of tingling chills while listening to a powerful piece of music, watching a moving scene in a film, or experiencing awe. This sensation is called frisson, and it has a completely different mechanism from fever-related chills. Brain imaging studies show that these aesthetic chills trigger the release of dopamine in the brain’s reward centers, the same regions activated during euphoria. The pattern of brain activity during frisson closely resembles what researchers see in studies of intense pleasure, with heightened activity in reward pathways and reduced activity in the brain’s fear center. Not everyone experiences frisson to the same degree, but it’s a well-documented neurological phenomenon, not just a figure of speech.
Managing Chills at Home
How you handle chills depends on the cause. If you’re running a fever, the chills are your body doing its job, so the goal is to stay comfortable while your immune system works.
For adults with a fever under 102°F, rest and fluids are usually enough without any medication. Above 102°F, acetaminophen (Tylenol), ibuprofen (Advil), or aspirin can bring the temperature down and relieve discomfort. For children, the same 102°F threshold applies, but aspirin should never be given to children or teenagers. For infants under 6 months, no fever-reducing medication should be given without medical guidance.
Light blankets are fine if you’re shivering, but avoid bundling up heavily, as that can trap heat and push a fever higher. Stay hydrated, since fever increases fluid loss through sweating and faster breathing.
For chills caused by cold exposure, the priority is gradual rewarming with dry blankets, warm beverages, and getting out of the cold environment. If someone has stopped shivering despite still being very cold, that’s a sign of worsening hypothermia and requires emergency care.
When Chills Signal Something Serious
Most chills are temporary and resolve on their own or with basic care. But certain patterns deserve prompt attention. A single hard rigor with sudden high fever in an adult can indicate a serious bacterial infection like pneumonia or a bloodstream infection (sepsis). Chills accompanied by confusion, rapid breathing, or a fever that won’t respond to medication suggest the body is struggling to contain an infection. Recurring chills with unexplained weight loss or drenching night sweats over several weeks can be a sign of conditions like lymphoma or tuberculosis that need evaluation. In people with diabetes, chills combined with shakiness, sweating, and dizziness point toward dangerously low blood sugar that needs immediate correction with fast-acting carbohydrates.