Low-Grade Fever

1 Low-Grade Fever Summary

Fever, also known as hyperthermia or pyrexia, refers to a condition in which the body temperature is higher than normal. Normal body temperature is around 98.6˚F (37˚C).

The temperature of the body may fluctuate through the day, with a low temperature in the morning which gradually increases in the afternoon and evening. In adults, fever is defined as body temperature 100˚F or higher (>37.8˚C).

In children temperature exceeding 99.5˚F (>37.5˚C) is considered as fever. Under normal conditions, an increase in body temperature helps to fight off disease-causing organisms. A fever is the first response or signal of infection in the body and is one of the most commonly diagnosed conditions.

Fever can be categorized as low-grade or high-grade. Low-grade refers to a mild increase in body temperature and often ranges from 100.4˚F – 102.2˚F. A body temperature that goes above 102˚F is categorized as high-grade fever.

Body temperature can be measured using an oral, rectal or axillary thermometer, depending on the location of checking the temperature. An increase in body temperature often accompanies an infection, but may also be seen with physical activity, high external temperature, and wearing thick clothing.

Some of the symptoms that may accompany low-grade fever include:

  • Abdominal pain
  • Cough
  • Diarrhea
  • Rashes on skin
  • Increased frequency of urination
  • Pain while urinating
  • Redness on skin
  • Breathlessness
  • Sore throat
  • Difficulty breathing
  • Neck rigidity
  • Discoloration of lips or nails
  • Muscle pain, joint pain, severe headaches, or ear pain
  • Diminishing level of consciousness
  • Difficulty to perform normal physical tasks like walking
  • Irritability in children
  • Decreased appetite
  • Ear pulling in children

A low-grade fever may affect appetite and cause morning stiffness. Swollen lymph nodes and joint deformity may also be seen along with low-grade fever. Children may show ear-pulling habit.

Fevers frequently come along with infections, and fever is a part of the body’s natural defense system against these infections. The body’s temperature can also rise due to other factors like rigorous physical activities, wearing thick and dense clothes, and other environmental factors like high temperature in the weather.

A low-grade fever can also happen after taking vaccines or immunizations, during teething, or as a sign of cancer or other serious diseases. And it can also happen due to the side effects of some medicines.

A low-grade fever may happen due to several reasons in adults and children such as due to specific infections, long term diseases, or due to some treatments which may weaken your immune system like cancer therapies.

Some of the symptoms that indicate a life-threatening condition include: 

  • Change in mental condition like lethargy, delirium, or hallucinations
  • Pain in the chest or chest tightness
  • Reduced frequency of urination
  • Rapid heart rate
  • Shortness of breath
  • Seizure
  • Severe pain
  • Blood in vomit or stool
  • Skin nodules
  • Swelling
  • Feeling hot without perspiring

Low-grade fever may be caused by infections, physical activity, immunizations, teething, or as a symptom of a serious medical condition.

Infectious causes of low-grade fever include bacterial infections, cellulitis, viral infections like flu, ear infection, gastroenteritis, HIV/AIDS, lung infections, parasites, urinary tract infections (UTIs), and sinus infections.

A low-grade fever is also a symptom of many cancers, inflammatory bowel disease, side effect of certain medications, vasculitis, and pulmonary embolism.

Some serious, potentially life-threatening causes of low-grade fever are an acute liver infection, appendicitis, cancer, diverticulitis, encephalitis, epiglottitis, heat exhaustion, meningitis, osteomyelitis, and pancreatitis.

Diagnosis is based on medical history, signs and symptoms, and physical examination. Information on the onset, factors that worsen or improve fever, chronic medical conditions, recent travel, other accompanying symptoms, and current medications help in identifying the probable cause of the condition. Other tests and investigations are based on the probable cause of the fever.

Medications like ibuprofen, acetaminophen, and aspirin are the most commonly suggested method for treating fever. Serious symptoms should be brought to the attention of doctor for early diagnosis and treatment of the underlying condition.

One should remain well hydrated by having plenty of fluids while having a fever. Good amount of rest also helps to alleviate the symptom. Light clothing and cool room temperature may also be of help during low-grade fever.

When left untreated, fever may increase the risk of complications like brain damage, anemia, physical disability, heat stroke, shock, the spread of cancer, and spread of infection.

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2 Causes

The most common cause of fever is an infection, including viral, bacterial and fungal. Physical activity is also known to cause an increase in temperature. Wearing thick clothing, and high temperature in the surroundings may also cause a low-grade fever.

In infants, low-grade fever refers to a rectal reading of 100.4˚F-100.9˚F, and an oral temperature reading of 99.5˚F -101˚F.

The common causes of low-grade fever in children are:

  • Flu - Flu and the common cold are the most common viral infections that lead to fever. The weak immune system in children increases the risk of viral infections that lead to these conditions.
  • Upper respiratory tract infection – it may result in other symptoms like stuffy nose, cough, and sore throat.
  • Gastrointestinal tract infection – infection of the gut may be caused by bacterial or viral infections. Vomiting and diarrhea are other symptoms of this infection.
  • Teething – this increase in body temperature is seen in children above 3 months. Starting of teething may result in a slight fever.
  • Chickenpox – chicken pox is a viral infection that causes fluid-filled blisters on the skin. It may also cause fever and headache as symptoms.
  • Measles – this is another viral infection that leads to rashes on the skin. A low-grade fever is an accompanying symptom of this infection.
  • Mumps – mumps is a viral infection of the salivary glands that leads to symptoms like swelling in cheeks and fever.
  • Urinary tract infection – UTIs may sometimes have a fever as the only symptom of the condition. Other symptoms when present include the characteristic strong-smelling urine.
  • Immunizations – certain immunizations may cause a low-grade fever that resolves within one or two days.
  • Chronic allergies – chronic allergic reaction to irritants may result in fever. This may not be accompanied by any other characteristic symptoms other than low-grade fever.
  • Other causes – other causes of fever in children include rubella, bladder infection, ear infection, roseola, Coxsackie viral infection, and dengue.

In adults, the common causes of fever are:

  • Infections – as in children, a number of infections may lead to fever. Bacterial infections leading to pneumonia, sinusitis, bronchitis, and typhoid cause fever as symptoms. Tuberculosis, a bacterial infection, is characterized by persistent low-grade fever. The most common viral infections that lead to fever are flu and the common cold. Other viral infections like chickenpox, hepatitis, and HIV/AIDS also cause an increase in body temperature. Fungal infection is also known to cause pyrexia. The accompanying symptoms may vary with the type of infection.
  • Allergy – allergies like hay fever have a fever as one of the symptoms other than a runny nose, cough, and skin rashes.
  • Certain medications – increase in body temperature caused by certain medications is known as drug fever. Fever, in this case, may resolve once the drug is stopped.
  • Pelvic inflammatory disease – this is a bacterial infection of the reproductive system in women. It causes recurrent fever and needs medical attention to prevent the spread of infection.
  • Appendicitis – fever may also result from inflammation of the appendix. A low-grade fever is a common symptom accompanied by abdominal pain and cramps.
  • Cancer – certain types of cancers, like lymphoma, may lead to mild fever.

3 Diagnosis and treatment

A doctor will review your medical history and evaluation of signs and symptoms to know the terms and reasons behind your low-grade fever. A physician will conduct this evaluation through a physical examination, considering all factors that may relate to the cause of the low-grade fever.

Information on the onset of fever, other accompanying symptoms, immunization status of the patient, recent travel details, exposure to infections, current medications, exposure to animals or other irritants, medical history, and allergies can provide important clues about the cause of the fever.

Other tests and investigations are suggested based on the possible cause to confirm the diagnosis.

Some common tests suggested in the diagnosis of underlying cause are: 

Blood tests help to rule out chances of infections that cause fever. An allergy test is recommended if allergic reaction if medical history shows the presence of this medical condition.

More investigations are suggested if the above-mentioned tests do not reveal the cause of the fever. For fever of unidentified origin, doctors may suggest other tests like endoscopy, PET scan, or echocardiography.

Treatment for low-grade fever

Treatment varies with the actual cause of the fever. In most of the cases, medications like acetaminophen and ibuprofen are used to reduce body temperature.

Viral infection often resolves without any specific treatment. Medications are given to control certain symptoms like fever, congestion, or a sore throat. IV fluids and medications are suggested if the infection cause vomiting and diarrhea. Antiviral medications are used in some viral infections like influenza.

Bacterial infections that cause fever are controlled by antibiotics. Hospitalization may be required based on the physical condition of the patient.

Fungal infections are treated with antifungal medications. Drug fever is controlled by stopping the drug that induces fever. Immediate results are seen in drug fever when the specific drug is stopped.

Patients with a weak immune system may require close monitoring and hospitalization to prevent infections. Sometimes one infection may lead to another serious infection and the fever can go out of control. Close and constant monitoring of such patients may help to get rid of the fever and other problems arising due to a weak immune system.

Sometimes, fever may spread through infected water. It is important to purify drinking water before consumption.

Fever caused by heat exhaustion is a medical emergency and the person needs to be cooled immediately.

Follow-up is needed to ensure that the underlying condition is treated completely. If fever persists for more than three days even after the start of treatment, it is important to see the doctor.

Since infections are the most common causes of fever, preventing infection is the best way to prevent fever. 

You can keep yourself protected by:

  • Washing hands frequently and avoiding touching face and mouth
  • Avoiding contact with infected people
  • Avoiding sharing of cups, clothes, and utensils to prevent spread of infection
  • Avoiding substance abuse
  • Having plenty of water during strenuous exercise
  • Keeping the body hydrated while working in warm atmospheres

Fever can be caused by various medical reasons ranging from not so serious to possibly fatal. Fever often resolves without any specific medication or with minimum medications. Young children and those with low immunity may need specific medical attention as being negligent in their cases may be life threatening. Timely and appropriate treatment of the underlying condition helps in controlling fever. As the condition is treated, body temperature also comes back to normal. Medicines help to get rid of the fatigue caused due to the persistent fever.

Fever is potentially life-threatening only in certain conditions, like meningitis. In elderly people and young children, pneumonia with fever is serious. One needs to be attentive in such cases. Early diagnosis and treatment are important in the case of persistent low-grade fever. Timely diagnosis and treatment will help the patient to get back to normal routine at the earliest, and after getting cured, it’s important to be careful about diet and medications to regain lost body strength.

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