Shivering

Shivering is the rapid contraction and relaxation of muscles, a response which helps the body to produce heat when it is cold. It is also referred to as chills when it is associated with paleness and feeling cold.

It is most often associated with the onset of infection and may indicate the start of the fever. It is very common among children. Shivering is an important symptom of a number of conditions. Rigor refers to exaggerated shivering which accompanies high fever.

Shivering of the body is actually a reflex which helps to raise the temperature. The trigger is controlled by the anterior hypothalamus, also known as an internal thermostat. It sets the body temperature at normal and changes it according to the changes in the internal environment.

With infection and inflammation, pyrogens are released in the body which change the trigger temperature. This resets the temperature control and the body starts feeling cold. The hypothalamus then increases the body temperature to beat the cold.

Shivering and rigor are less likely to occur among elderly people. It may be caused by a number of factors including cold weather, sensitivity to cold, fever, menopause and panic attack. A number of bacterial and viral infections also have to shiver as one of the symptoms.

Drug withdrawal may also cause shivering in some people. When the fever is mild and no side effects are seen, shivering need not have any specific treatment. But there are some associated or accompanying symptoms which call for medical attention.

Doctor visit is needed if shivering is accompanied by: 

• Confusion
• Stiff neck
• Irritability
• Shortness of breath
• Abdominal pain
• Frequent urination
• Fever above 103˚F even after treatment at home
• Fever persists for more than 3-5 days

Children under 3 months with shivering and fever more than 101˚F should be immediately taken to the doctor. This is also true of infants 3months to one year of age who has fever persisting for more than a day.

The cause of shivering and fever is diagnosed on the basis of medical history and physical examination.

The doctor collects information on highest body temperature reached during fever, a number of episodes of shivering since its onset, duration of each episode of shivering, any chance exposure to allergic items 4-6 hours before the onset of shivering, whether the onset was sudden or gradual, and other symptoms present.

During the physical examination, the doctor may focus on the health of eyes, ears, nose, throat, chest and abdomen. The doctor may recommend other tests based on the probable cause of the condition.

Some other tests and investigations suggested include blood tests, blood culture, sputum culture, urine analysis, urine culture, and imaging techniques like an x-ray.

Treatment of shivering depends on the duration of shivering and the accompanying symptoms of the condition. Efforts are on to reduce the body temperature, particularly in children.

Antipyretics are not continuously used in children to achieve the same unless the child is distressed due to fever. The source of infection, when present, is treated to control fever and shivering.

If the patient is unwell for a long duration, hospitalization may be required to diagnose and treat the underlying cause of fever and shivering.

Major causes of shivering are: 

• Cold environment
• Infections, both bacterial and viral

Some of the infections that have shivering as one of the symptoms include: 

• Bacterial gastroenteritis – this is a condition characterized by inflammation of the intestine and stomach caused by bacterial infection. It occurs more commonly in groups who had food at large social functions or restaurants.
• Common cold – in some cases, common cold may cause shivering along with a runny nose, nasal congestion, and sneeze.
• Infectious mononucleosis – is a viral infection characterized by swollen lymph glands, fever, and sore throat. The fever may be accompanied by shivering which is a less common symptom of the condition.
• Influenza – or flu is a viral infection of the lungs, nose, and throat. The symptoms resemble that of cold but are usually accompanied by fever and shivers.
• Meningitis – bacterial infection of the meninges, the covering of the brain and spinal cord, is also a cause of shivering. Meningitis may be caused also by viral infections. Fever and chills are common symptoms of meningitis.
• Pneumonia – infection of the lung resulting in respiratory disease is referred to as pneumonia. Pneumonia may be caused by bacteria or viruses. The most common symptoms of pneumonia are fever and shivering.
• Strep throat – it is a bacterial infection that causes a sore throat. It is characterized by fever, chills and swollen glands in the neck.
• Viral gastroenteritis – or stomach flu, as it is commonly called abdominal pain, fever, chills, and diarrhea.
• Urinary tract infections – infection of the urinary tract including bladder, ureters, and urethra is known as urinary tract infections. Chills and shaking is a common symptom of this condition, particularly if the infection spreads to the kidneys.

In children, shivers are often confused with febrile convulsions and in adults, it is confused with fits. Many other conditions have shivers and high fever as the symptoms including cardiac conditions like infective endocarditis, pericarditis, and Dressler’s syndrome.

Among the pulmonary diseases, severe acute respiratory syndrome, or SARS, also have shivering or rigor as one of the symptoms. Genitourinary conditions like pyelonephritis, prostatitis, and prostate cancer are also reported to have shivering as one of the symptoms.

Shaking rigors are common after parturition. Epidurals are also associated with severe shivers. Septic arthritis and rheumatic fever are two rheumatological conditions that have shivers as symptoms.

Other infectious diseases like meningococcal septicemia, malaria, rat-bite fever, filariasis, brucellosis, tuberculosis, Lyme disease and louse-borne relapsing fever are all associated with rigors.

Apart from viral gastroenteritis, acute cholangitis, and ulcerative colitis also have rigors as common symptoms. Shivers are one of the symptoms of intravenous drug interactions for medications like gentamycin, vancomycin, interleukin-II, amphotericin, and anti-TN alpha drugs.

Many transfusion processes also cause shivers. This includes many types of blood product transfusion commonly used for some conditions. Severe rash on the body, particularly in children, is associated with shivers.

Shivers are also seen after hemodialysis, radiotherapy, bone marrow transplant, catheterization, and infections associated with postsurgical care.

Medical history and physical examination are two important steps in identifying the underlying cause of shivering. The doctor may try to analyze whether it is shivering or just feeling cold.

The highest body temperature recorded during the episode, periodicity of each episode, duration of the shivers, exposure to allergic substances, recurrence of shivering episode, accompanying symptoms, and the onset of shivers are also noted.

These details will help the physician to find the most probable cause of shivers. In most of the cases, medical history may reveal the source of infection. In the case of children who are having shivers, hospitalization may be required for investigations and monitoring.

In physical examination, both low and high body temperature may cause shivering. Heart murmur during the examination of the heart may reveal bacterial endocarditis. Pneumonia and bronchiectasis are revealed by noises in the examination of lungs.

The abdominal examination will help to detect enlargement of the liver. Physical examination of the nervous system for symptoms of sinus thrombosis, brain abscesses, and encephalitis, may also indicate the cause of shivering.

Physical examination may also help to detect osteomyelitis. Pulse rate, shallow breathing, shivering, muscle stiffness, and blood pressure are also noted and connected to the underlying cause that may result in shivering.

Other tests and investigations are done for identifying the cause include: 

Blood tests like complete blood count, erythrocyte sedimentation rate, liver functions tests, serial blood cultures, and phase serology tests for viruses. Other tests like urinalysis, urine microscopy and culture, sputum culture and stool culture are also used in specific diagnosis.

Radiological testing suggested for the diagnosis are an x-ray of suspected areas, cholecystogram, echocardiogram, angiography, bone scan, and CT scan.

If the body temperature is less than 102˚F with no accompanying symptoms, no specific treatment may be required for controlling the symptom. Home care with adequate hydration and plenty of rest are the best steps for bringing down fever.

Sponging with warm water also is helpful in reducing fever. Over-the-counter medications like acetaminophen may be of help in regulating body temperature. Antipyretic agents should not be continuously used for reducing body temperature. Antipyretics are recommended if the fever is causing distress in children.

Medical attention is required if shivers are accompanied by stiffness of the neck, confusion, irritability, shortness of breath, abdominal pain, and frequent urination. Children younger than 3 months should be taken to the doctor if fever persists for more than a day.

Children with shivering should not be bundled up in blankets or be woken to give medication. Air conditioners also should be avoided. To reduce the body temperature, warm water sponging is suggested.

Sponging with ice water or alcohol should be strictly avoided as it may increase shivering. Ensure that the child is wearing light clothing. The room should be comfortably cool for the child.

Dosage guidelines should be strictly followed in case of medications. Aspirin is not suggested for children below 19 years. Rest is very important in recuperation, and hence a sleeping child should not be woken up for taking the temperature.