Chills

Chills are a sudden feeling of coldness, often with shivering, that can happen for many different reasons. Cold environments, infections, low blood sugar, stress, or certain health conditions like hypothyroidism can trigger chills. Sometimes chills occur with a fever, but they can also happen even when body temperature is normal.

Identifying what causes chills can help people decide whether they need to seek medical attention or just add another layer of clothing. Many common causes are not serious, but watching for other symptoms that come with chills can give helpful clues about what’s really going on.

Definition of Symptom

Chills are a physical sensation where a person feels cold, sometimes very suddenly. This feeling may happen with or without actual exposure to cold temperatures. Chills often come with shivering, which is the body’s automatic reaction. When muscles contract and relax quickly, the body tries to warm itself. Sometimes, people notice their teeth chattering or their body shaking.

A person can experience chills with or without a fever. When chills occur with fever, infections or illnesses are often the cause. Without fever, other causes like low blood sugar, cold environments, or certain health problems may be involved. Some common signs of chills include:

• Sudden feeling of coldness
• Uncontrollable shaking or trembling
• Goosebumps on the skin

Chills can last for a few seconds or several minutes. Most of the time, chills are not dangerous, but in some cases, they may point to health issues that need attention.

Possible Causes/Diseases Condition

Many things can cause chills. Fever, often linked to infections like the flu, cold, or pneumonia, is a common cause. When the body fights bacteria or viruses, it raises the internal temperature, which can make a person feel cold and shiver.

Not all chills come with a fever. Sometimes, chills without fever may signal other health problems. These include exposure to cold weather, anxiety, or certain medications. Low blood sugar can also lead to chills. People with diabetes may experience this, especially if they miss a meal or take too much insulin.

Some health conditions may cause chills, even without obvious signs. Cancer, autoimmune diseases, and reactions to medications can all be triggers. In these cases, chills might be an early sign of illness. Below is a list of possible causes of chills:

• Infections (bacterial or viral)
• Fever
• Hypoglycemia
• Cold exposure
• Reactions to medication
• Cancer
• Anxiety or panic attacks
• Anemia
• Hormonal changes (like menopause)

Cause	With Fever	Without Fever
Infection	✓
Cold exposure		✓
Hypoglycemia		✓
Medication reaction	✓	✓
Cancer	✓	✓
Anxiety		✓

Other Non-Disease Causes

Chills are not always a sign of illness. Several non-disease factors can trigger chills in healthy people. Emotional responses like anxiety or stress often cause chills. These feelings can activate the body’s “fight or flight” response, leading to shivering or chills even in a warm room.

Fatigue can also play a part. When someone is very tired, the body may have trouble keeping a steady temperature, causing chills. Hormonal changes sometimes lead to chills. For example, people going through menopause may experience hot flashes followed by chills as the body cools down after a sudden rise in temperature.

Dehydration affects the body’s ability to control temperature. When someone is dehydrated, chills may occur, especially after physical activity. Caffeine can increase heart rate and make the body feel jittery, leading to chills or shivers in some people. A quick table below shows these non-disease causes:

Cause	How It Triggers Chills
Anxiety	Activates body’s stress response.
Stress	Boosts adrenaline, leads to shivers.
Fatigue	Reduces temperature control.
Menopause	Causes hot flashes and chills.
Dehydration	Affects temperature regulation.
Caffeine	Stimulates nerves, causes jitters.

How It Causes the Symptom

When the body wants to raise its temperature, the muscles quickly contract and relax, which produces heat and makes a person feel cold, even if the environment is not chilly. Some common triggers include infections, exposure to cold air, and certain health conditions.

When the immune system senses a threat like a virus or bacteria, it may release chemicals that reset the body’s thermostat in the brain. This response can cause body temperature to rise, leading to chills and often sweating as the body tries to balance heat. Sweating may follow chills to help cool the body if the temperature gets too high.

Other causes, such as low blood sugar or anxiety, can affect how the body controls heat. In these cases, the body may react as if there is a real temperature change, even when there is not. Below is a quick list of ways chills can develop:

• Sudden drop in body temperature (exposure to cold)
• Fever response to infection
• Hormonal shifts like those in menopause
• Intense exercise
• Low blood sugar

Possible Complications

Untreated chills may signal a more serious underlying health problem. If an infection causes chills, it can sometimes lead to problems like pneumonia or blood infections, especially if fever is also present. People with weakened immune systems need to be extra careful.

Some people experience chills along with other symptoms, such as night sweats or unintentional weight loss. These combinations could point to infections like tuberculosis or conditions such as some cancers. Prolonged or frequent chills can also cause fatigue, dehydration, and muscle discomfort. This may make it harder for someone to rest or recover from illness.

In some cases, chills and frequent shivering may raise the risk of falls or injuries, especially in older adults. Shivering can cause muscle weakness and temporary loss of balance. People with chronic illnesses, like anemia or thyroid problems, might notice their other symptoms get worse if the cause of the chills is not treated. Below is a table with possible complications:

Complication	Associated Symptom
Infection worsening	Persistent fever
Night sweats	Intense sweating during sleep
Weight loss	Losing weight without trying
Dehydration	Dry mouth, weakness, dark urine
Injury risk	Falls due to shivering and fatigue

When to Seek Medical Attention

Not all chills mean something serious, but some signs should not be ignored. If chills are frequent, severe, or last longer than a few days, contact a doctor. See a doctor if chills occur with any of the following:

• High fever that lasts more than three days
• Difficulty breathing
• Chest pain
• Confusion or trouble staying awake
• Stiff neck or severe headache
• Ongoing fatigue or muscle aches
• Rash that spreads quickly

Frequent chills without a clear cause may point to an underlying problem. If you have a weak immune system or ongoing health issues, you can get infections more easily.

Table: When to Seek Help for Chills

Symptom	Action
High fever + chills	See a doctor
Trouble breathing or chest pain	Seek urgent care
Chills with confusion	Get medical help right away
Rash, stiff neck, or severe pain	Contact a doctor
Chills that don’t stop	Make a medical appointment

If allergies are ruled out and chills are not linked to cold weather or mild illness, talk to a healthcare provider to find the cause and get the right treatment. Listen to your body and get help if something feels wrong.