Chills (shivering) are caused by rapid alternation between muscle contractions and relaxation. These muscle contractions are a way your body tries to warm itself up when you’re cold.

Chills are often, though not always, associated with fever. Sometimes, they precede the onset of fever, especially if the fever is caused by an infection. Other times, they occur without a spike in temperature. Chills may or may not be serious, depending on the underlying cause.

7 Causes
Chills without fever can be caused by a number of conditions.

1. Exposure to cold

You may experience chills because you are in a very cold place, such as the ocean or a pool, or outside on a chilly day. You can also get chills if your clothing becomes damp or wet. You can get chills indoors, too, if the air-conditioning is set too cold or the heat isn’t hot enough.

As the human body ages, it has a more difficult time regulating body temperatureTrusted SourceTrusted Source, even in healthy older adults. Medical conditions such as diabetes and heart disease can make the problem worse.

These types of chills should dissipate as soon as your body warms up. However, if you experience continual shaking when you have been exposed to intense cold, you may have developed complications such as hypothermia or frostbite, which are both potentially serious.

Other symptoms of these conditions can include:

numbness
changes in skin color
slurred speech
extreme drowsiness
stinging or burning sensation, particularly in the fingers, toes, ears, or nose
blisters
Seek immediate medical help if you suspect hypothermia or frostbite.

2. Medication side effect

Chills without fever may result from taking certain medications or combinations of medications. They may also occur if you take the incorrect dosage of an over-the-counter medication, herbal supplement, or prescription drug.

Always read the potential side effects information included with medication packaging. If you suspect that you’re having chills because of a drug or drugs you use, let your doctor or pharmacist know immediately. Depending on the severity, you may require medical attention.

3. Reaction to extreme physical activity

Marathon running or other forms of extreme sports that require intense physical exertion may cause changes to your core body temperature. That can result in chills.

This response can happen in any type of weather but may be more likely to occur in very cold or very hot temperatures:

In hot temperatures, heat exhaustion and dehydration may cause this reaction.
In cold temperatures, hypothermia and dehydration may be the cause.
In both instances, other symptoms you might experience include:

goosebumps
muscle cramping
dizziness
fatigue
nausea and vomiting
You can avoid chills from exercise by remaining hydrated and dressing appropriately for your workouts. Consider avoiding exercise during the coldest or hottest times of day and also limiting the duration of time spent in intense activity.

Hydrating and getting your temperature back into a normal range are usually enough to eliminate your symptoms.

In some instances, though, you may require IV fluids to treat the condition.

4. Hypothyroidism (underactive thyroid)

An underactive thyroid is a thyroid gland that doesn’t produce enough of the hormones needed to regulate metabolic rate or support overall health. This condition can cause an increased sensitivity to cold, resulting in chills.

Additional symptoms associated with hypothyroidism include:

puffiness in the face
unexplained weight gain
dry skin, nails, and hair
muscle weakness, pain, or stiffness
depression or feelings of sadness
trouble with memory
constipation
Hypothyroidism is diagnosed through a blood test. It’s a treatable condition and typically requires daily medication.

5. Hypoglycemia

Hypoglycemia occurs if blood sugar levels dip abnormally low. If you have diabetes, it may be a sign that your medication or diet needs to be adjusted. It’s also possible to experience hypoglycemia without diabetes.

Hypoglycemia requires immediate treatment to get blood sugar levels back to normal. One of the symptoms of hypoglycemia is a feeling of shakiness or muscle weakness, which may mimic chills. Other symptoms of this condition include:

sweating
irritability
heart palpitations
tingling feelings around the mouth
confusion
seizures
blurred vision
6. Malnutrition

Malnutrition occurs when your body lacks necessary nutrients. This can happen because of poor access to nutritious foods, an underlying condition that affects your body’s ability to properly absorb nutrients, or an eating disorder, like anorexia. Without the correct balance of nutrients, your body can’t properly function.

Other symptoms of malnutrition include:

fatigue or sleepiness
weakness
difficulty concentrating
pale skin
rashes
heart palpitations
feeling faint or lightheaded, or fainting
tingling or numbness of the joints or extremities
in women, missed periods, heavy menstrual cycles, or infertility
Talk to your doctor if you suspect malnutrition. This is a serious condition that can lead to complications if left untreated.

7. Emotional reaction

Chills can occur if you have a profound or intense emotional reaction to a situation. Emotions that might cause chills include fear or anxiety.

Chills can also be caused by experiences that move you deeply in a positive way, such as listening to music or inspirational words.