11 most common causes
Why are you having chills?
Chills can be uncomfortable. You may be wrapped in the heaviest down blanket, but still unable to get warm. You may feel cold and clammy, or you may be sweating with a fever and feeling overheated.
Chills, or shivering, can happen one time or they can be frequent. They can last a few seconds or as long as an hour. Sometimes chills can cause noticeable shaking movements; other times visible symptoms are minimal—you may just feel chilled to the bone.
Chills are your body’s attempt to raise your internal body temperature if you’re cold or sick. When your muscles involuntarily contract and relax, it generates heat. If you’re sick, chills can create more heat to help kill a virus or bacteria.
Chills can also be caused by menopause, low blood sugar levels, or when you’re experiencing profound emotions like shock, fear, or anxiety.
Extreme exertion—such as running a marathon—can also cause chills as your body tries to regulate temperature to avoid overheating.
1. Gastroenteritis (stomach flu)
Gastroenteritis, or stomach flu, is inflammation of your gastrointestinal organs, like your stomach and intestines. It is usually caused by infection with a virus, such as the rotavirus or norovirus. Most people recover on their own in a few days without any specific medical treatment beyond caring for themselves at home.
It is very important to stay hydrated as the body can lose a lot of water and electrolytes from throwing up or diarrhea. If you think you’re dehydrated or cannot keep any foods or liquids down, talk to your doctor. Your doctor may recommend hospitalization for monitoring and IV fluids for rehydration.
Also, gastroenteritis can sometimes mimic other more serious conditions such as appendicitis, which often has symptoms like fever, nausea and vomiting, and belly pain. Call your doctor when in doubt about the cause of your symptoms.
2. Influenza (flu)
- Body aches
- Nausea, vomiting, diarrhea (especially in young children)
The flu is an infection of the respiratory tract (your lungs, nose, and mouth) caused by the influenza virus. There are different types of flu viruses. The reason you need to get a flu shot every year is because the version it protects against changes.
Most people who get the flu recover in a few days. Sometimes, it develops into pneumonia, which can be life-threatening, especially for the elderly or people with compromised immune systems.
If you are at risk of severe flu symptoms, see your doctor right away or go to urgent care. They may prescribe an antiviral medication. It can reduce how many days you are sick and the risk of complications.
Treating the flu is about taking care of your symptoms. You can take over-the-counter pain relievers like acetaminophen or ibuprofen. Get plenty of rest and drink lots of fluids.
It’s important to see a doctor if symptoms don’t get better or your fever lasts for more than 3 to 5 days.
Sometimes patients tell me that they feel “silly” about bringing up questions about their chills. We are always here to help patients and hear their concerns. You mentioning your chills could be a vital step in first alerting us that something may be wrong with your health. —Dr. Petrina Craine
- Cough (which may also produce mucus/phlegm)
- Trouble breathing or increased breathing rate
- Chest pain
- Nausea, vomiting, loss of appetite, and diarrhea (especially in younger children)
- Confusion (especially in the elderly)
Pneumonia is an infection in your lungs that is usually caused by viruses and bacteria. The infection irritates the air sacs, filling them with pus and other fluids. Colds, bronchitis, influenza, and other respiratory infections can become pneumonia as bacteria settles into your lungs.
Pneumonia can be life-threatening, especially to the elderly or people with compromised immune systems.
Pneumonia is often diagnosed with a chest x-ray. Pneumonia caused by bacteria can be treated with antibiotics and many people can continue taking the medication as they recover at home.
You may have to be admitted to the hospital if you have low oxygen levels, severe dehydration, or other complications.
- Loss of taste or smell
- Cough or congestion, which may produce mucus
- Runny nose
- Nausea, vomiting, or diarrhea
- Chest pain
- Body aches
- Low oxygen levels on a pulse oximeter (oxygen measuring device)
COVID-19 is a highly contagious virus caused by a coronavirus, specifically the SARS-CoV-19. This virus infects the respiratory tract (including your nose, throat, sinuses, and lungs). Although it is a respiratory infection, it can also affect other organs including the brain, blood vessels, and the skin.
Symptoms are very similar to those seen in the flu and the common cold. Sometimes, cases of COVID-19 that begin with mild symptoms worsen and become life-threatening. COVID-19 is very contagious, even when people don’t have symptoms.
Rest and hydration can be important in treating symptoms and feeling better for people with mild cases of COVID-19. If you suspect COVID-19, monitor your symptoms and speak with your doctor about your condition.
They will give you additional at-home treatment plans. These may include over-the-counter medication, oxygen-monitoring devices, or prescription medication, like an inhaler. They can also advise you when to go to the hospital if your symptoms get worse.
- Runny nose
- Facial pain or pressure
- Cough that may produce mucus
- Foul-smelling breath or taste in mouth
The sinuses normally produce thin mucus to help trap foreign materials. When infected with viruses or bacteria, this fluid often increases and gets thicker—causing blockages. The infection affects the small air pockets in your forehead, nose, cheekbones, and in between your eyes. This is called sinusitis. Most sinus infections are caused by viruses, so antibiotics won’t help treat symptoms. If your symptoms last longer than 10 days or get worse after 5 to 7 days, you may have a bacterial infection. Your doctor may prescribe antibiotics.
Over-the-counter decongestants (such as pseudoephedrine) should be used with care. Taking beyond 3 days may lead to an increased risk of the congestion coming back. It can sometimes be even worse than before. Watch your symptoms. Hydrate (liquids like water and tea) to help relieve pressure.
6. Strep throat
- Sore throat
- Painful swallowing
- Tender lymph nodes
- Swollen, red tonsils
Strep throat is a throat infection caused by a bacteria called group A Streptococcus. Strep throat is contagious and more common in children than adults. A main symptom is a very sore throat that can make eating, talking, or swallowing difficult. Sometimes, you get strep throat with a rash that looks like sandpaper—this rash is known as scarlet fever.
Strep throat is diagnosed with a test. It is treated with antibiotics. If not treated, strep can turn into a more serious illness such as rheumatic fever. Antibiotics may make you feel better within a few days, but you must take the antibiotics for the full amount prescribed.
Not all chills are necessarily negative. Some happen after deeply positive emotions, like after experiencing inspiring or moving music. This reaction is called “frisson.” —Dr. Craine
7. Urinary tract infection (UTI)
- Painful urination
- Increased urge or frequency of urination
- Pain in pelvic or rectal area
- Back pain
- Fever and chills (more so for an upper UTI)
- Nausea or vomiting
- Confusion (especially in elderly)
A urinary tract infection is an infection of your urinary tract that can affect the bladder, the urethra (the tube you urinate through), or the kidneys, which filter urine. This infection is commonly caused by bacteria but can also be caused by other germs like fungi. Pregnant women are prone to UTIs.
Most people who experience chills from a UTI have an upper urinary tract infection. This is a sign that your kidneys and ureters (inner tube that passes urine from the kidneys to the bladder) are infected.
A UTI is diagnosed with a urine sample and can be treated with antibiotics. If not treated, a UTI can become very serious and infect your kidneys (pyelonephritis) and your bloodstream.
8. Common cold
- Runny nose
- Cough and congestion
- Low fever
- Chills and body aches (usually mild)
A common cold is a viral infection of the respiratory tract (usually just your nose and mouth). Many types of viruses can cause it, but rhinoviruses are a common culprit.
Most people with the cold do not have severe symptoms and get better without complications. Over-the-counter medications, such as decongestants (such as pseudoepinephrine) and natural foods like honey (in ages 2 and older), may relieve symptoms like congestion, cough, and sore throat. Resting and staying hydrated can also help you feel better.
9. Medication side effect
- Recently taking or changing medications
Recovering from anesthesia after a surgery can sometimes cause chills. This is from anesthetics affecting body temperature regulation, the cool temperature of operating rooms, and your body cooling down while under anesthesia.
Abruptly stopping certain medications or substances, such as benzodiazepines, alcohol (in a person who drinks large amounts of it daily), or opioids like heroin or oxycodone (in a person dependent on them) can cause chills.
Let your doctor know if you’re experiencing chills as a reaction to a new medication or if you’re withdrawing from a medication or substance.
- Unexplained weight gain
- Dry, cool skin
- Leg and face swelling
- Decreased appetite
- Recently taking or changing medications
Hypothyroidism is a condition in which your thyroid is underactive. Thyroid hormones are involved in various body processes, a key one being metabolism. Low thyroid hormone levels increase your sensitivity to temperature changes and make you more likely to feel chilled.
Hypothyroidism can be caused by various conditions such as your immune system attacking your thyroid or a nutritional deficiency in iodine (an important mineral for thyroid hormone production).
Diagnosis is made with a blood test. Medications can be used to manage hypothyroidism.
- Fever that comes and goes
- Unexplained weight loss
- Easily bruised skin
- Swollen lymph nodes
Cancer can be associated with a persistent low-grade fever, as well as chills. This is especially true for certain blood cancers like leukemia, lymphoma, or myeloma.
See your doctor If a fever doesn’t break or you have a continual low-grade fever or a low-grade fever that seems to come and go. You may also notice other symptoms, such as unexplained weight loss, swollen lymph glands, or fatigue. Blood cancers may also cause symptoms that include easily bruised skin or bleeding gums.
Tests can be used to diagnose cancer. Treatment depends on the type of cancer and how far it has progressed. Treatment may include chemotherapy, radiation, and/or surgery.
12. Autoimmune disease
- Swollen glands
- Joint pain
- Digestive issues
- Skin or hair changes
Chills are often a symptom of various autoimmune diseases such as lupus and rheumatoid arthritis. Of those suffering from an autoimmune disease, nearly 80% are women. The reasons for this are not entirely clear, but hormonal changes (e.g. with estrogen and progesterone) and variations in sex chromosomes are thought to contribute to the large amount of women over men with autoimmune disorders.
Autoimmune disorders can have a range of symptoms and can be complicated to diagnose. Often, diagnosis is made by ruling out other causes. Treatment can include symptom management, medication, and immunotherapy.
Menopause is a period in a woman’s life in which her menstrual cycle ceases. It usually occurs between the ages of 45 and 55. Women experience significant changes in hormones, which can affect their body’s temperature regulation. It typically can cause “hot flashes,” but it can also cause chills. Chills can occur after a woman is “cooling down” after a hot flash or in place of hot flashes, a phenomenon known as “cold flashes.”
Your doctor may recommend blood tests to test hormone levels. Treatment can include symptom management with medications, including hormone-replacement therapy.
- Feeling cold or chills
- Lightheadedness or dizziness
- Palpitations (irregular, rapid, or particularly strong heartbeat)
- Chest pain
- Shortness of breath
Anemia occurs when your body doesn’t have enough red blood cells to carry oxygen to your tissues. This affects nearly every process in the body, including temperature regulation. There are different causes of anemia, including problems with iron (e.g., losing blood from colon cancer or heavy menstrual cycles). Anemia is more common in women than men, and can be a particular problem for pregnant women due to increased nutritional needs during pregnancy.
A doctor may recommend iron supplements.
Sometimes patients look for goosebumps—when the hair on your body sticks up on skin—when they feel chills. They are not the same. Goosebumps can happen with chills, like if you are outside in the cold or if you are having a strong emotional reaction. But they are not always present with chills, such as chills with fever. —Dr. Craine
Other possible causes
A number of conditions may also cause chills, though these are either rare or chills are not the defining symptom. These include extreme sunburn (rare), malaria, and tuberculosis.
When to call the doctor
- Chills persist even when you don’t have a fever.
- You have a cough, cold, or sore throat you can’t seem to shake.
- You experience body aches even when you haven’t exercised or exerted yourself.
- You have night sweats.
- You have a low-grade fever that doesn’t resolve, or seems to come and go.
- You notice hair or skin changes like your hair falling out.
- You’ve had unexplained weight loss.
- You experience fatigue regardless of how much you’ve slept.
- You experience constipation or diarrhea despite dietary changes.
Should I go to the ER for chills?
You should go to the emergency department if you have any of these signs:
- Rapid or irregular heartbeat that persists
- Skin color changes such as turning red, white, or black
- Shortness of breath
- Chest pain
- Fever (usually 102°F and greater)
- Confusion or hallucinations
- Dizziness or fainting
Those with weakened immune systems (e.g., elderly adults, babies, people with cancer, people on medications that suppress the immune system, people with chronic conditions like diabetes, kidney failure, etc.) should visit an emergency room as chills could be a sign of a severe infection brewing.
- Medications to help reduce fever such as acetaminophen (Tylenol) and non-steroidal anti-inflammatory drugs (Advil, Motrin)
- Drink lots of fluids
- Warming up if you’ve been outside in cold temperatures
Other treatments you might have
- Medical testing to help identify the cause of chills
- IV hydration
- Hospital monitoring
- Medication review to ID any medications or interactions that may cause chills as a side effect
- Prescription medication or additional treatments to treat the underlying cause of chills
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