DEFINITION
Fever is a symptom of many conditions and involves the increase in body temperature. Given that the normal body temperature is not the same in every location of the body, the definition of fever is also different. In the armpit, a very common temperature measuring region, normal temperature is between 96.08 °F and 98.6 V °F; every measurement that exceeds this value is a fever. When using an oral thermometer, temperature needs to be over 98.96 °F for fever to be present.

CAUSES
Fever is one of the most common symptoms for which people may ask to consult their doctor. It accompanies multiple diseases and disease types, which can range from mild to severe.

The following constitute some of the most frequently diagnosed causes of fever:

Infections
• Common cold
• Pharyngitis (an infection of the throat)
• Pneumonia or bronchitis
• Gastroenteritis
• Urinary tract infection or pyelonephritis (inflammation of the kidney)
• Cholecystitis (an infection of the gallbladder)
• Appendicitis (an infection of the appendix, which is a medical emergency)
• Meningitis (a severe infection of the central nervous system)
• Endocarditis (infection of the endocardium, one of the layers of the heart)
• Infectious mononucleosis
• Tuberculosis
• Malaria
• Abscesses, located in the spleen, liver, brain, pelvis or dental abscesses.

Non-infectious diseases
• Rheumatoid arthritis
• Vasculitis (an inflammation of the vessels, including Wegener’s granulomatosis, Churg-Strauss syndrome and others)
• Inflammatory bowel disease (Crohn’s disease, ulcerative colitis)

Cancer
• Lymphomas
• Pancreatic cancer
• Liver cancer

Fever can also be a result of the ingestion of a certain medication or be a reaction to a blood transfusion. There are multiple other conditions that cause fever to develop, which we will not be referring to here.

PRESENTATION OF THE MOST COMMON CONDITIONS MANIFESTING WITH FEVER

Common cold
The common cold is caused by viruses and causes fever, congestion and nasal discharge, cough, and hoarseness. Fever, which is present more commonly in younger people and not adults, it is not very high and lasts for a day.

Gastroenteritis
Gastroenteritis may be caused by bacteria, parasites or viruses. Typical symptoms include fever, diarrhea, abdominal cramps, nausea and vomiting.

Bronchitis
Bronchitis is an infection of the bronchi, the airways that are directly connected to the trachea. It manifests with fever mainly when caused by viruses. Additional symptoms are a productive cough and chest tightness.

Pyelonephritis
Pyelonephritis is an infection of the kidney, caused by microorganisms that have usually traveled upwards from the cyst. The characteristic symptoms are high-grade fever with chills, pain in the back, nausea and vomiting (sometimes).

Meningitis
Infection of the meninges, namely the membranes that encase the brain and spinal cord. Meningitis manifests with high fever, headaches, sensitivity to light, vomiting, disorientation or delirium, and, sometimes a rash.

Appendicitis
Infection of the appendix, which causes fever, pain in the lower right quarter of the abdomen, nausea, and anorexia. It is a medical emergency because the appendix may rupture and lead to a generalized infection.

Cholecystitis
Inflammation of the gallbladder. It is characterized by pain in the upper right quarter of the abdomen, fever and vomiting.

Malaria
Malaria is a potentially serious disease, transmitted by mosquitoes. In the past the fever had two distinct characteristics: it appeared every third or fourth day. Nowadays this clinical picture is uncommon, and this infection is also uncommon in the industrialized world. Fever tends to be irregular, high- or medium grade and can be accompanied by chills or delirium. Coma can also ensue.

Rheumatoid arthritis
Low- grade fever can accompany rheumatoid arthritis, alongside swollen and tender joints of the feet and hands, which may get deformed over time.

Crohn’s disease/ulcerative colitis
They both fall under the category of inflammatory bowel disease, and many physicians consider them to be the same disease. Diarrhea with mucus, colicky abdominal pain, fever, blood in the stool, weight loss and a decreased appetite are some of the symptoms involved.

Lymphoma
Lymphomas are tumors that develop from lymphocytes, a group of cells that are used to fight infection and disease in the body; lymphocytes are part of the immune system. Lymphomas can be located in many regions of the body and the symptoms depend on where they are. Some may produce no symptoms, whereas others may lead to fever, night sweats, weight loss, and anorexia.

Liver cancer
Liver cancer usually presents with fever, weight loss that is unintentional, anorexia, fatigue, weakness, a palpable mass under your right ribcage that is the engorged liver and jaundice, namely your skin that has assumed a yellow-ish color.

Drug-induced fever
Drug fever is a fever that appears after the ingestion of a drug and stops after this drug is discontinued. Other symptoms, such as skin rash, may co-exist.

WHEN TO SEEK TREATMENT
Fever is a symptom that, as seen above, can accompany many diseases which are very different from each other. It is generally not necessary to call your doctor as soon as you find out you are feverish. If you experience very high fever, above 100.4 °F, or if you experience fever with other alarming symptoms, such as bloody diarrhea, dyspnea, sensitivity to light, considerable weight loss over a period of time, persistent pain in the abdomen or back or disorientation, do consult your doctor right away. If the fever persists and does not respond to the standard drugs used to relieve it, also contact your doctor. Senior citizens and infants also need to be examined by a physician, as their immune system cannot fight an infection that presents with fever. In children, consider calling your doctor if your child has a fever that lasts more than 3 days, appears confused or disoriented or vomits continuously.

WORKUP
Your doctor will take a detailed medical history and perform a comprehensive physical examination that includes the throat, ears, neurologic evaluation, abdomen. He/she will also listen to your breath sounds with a stethoscope and take your vital signs (blood pressure, temperature, oxygen, and pulse rate). Depending on the precise symptoms accompanying the fever, they might also order blood tests, abdominal or chest x-ray, electrocardiogram, a stool culture or sputum culture and many more procedures which are highly dependent on the symptoms.

TREATMENT
Mild episodes of fever that do not require a doctor’s intervention may be treated at home with paracetamol (Tylenol) that helps body temperature to lower, fluids and rest. The treatment that your doctor will decide depends on the diagnosis. If you ingest even an over-the-counter medication such as Tylenol for the first time and experience one of the following, immediately discontinue the drug and contact your doctor: • Skin rash
• Dyspnea
• Fainting
• Diarrhea, vomiting or nausea

COMMON MISCONCEPTIONS
• I have heard that a fever of over 104 is the highest fever one can survive without brain damage.

Any fever over 102.2 °F needs to be cooled down in order to prevent it from rising more. In the same way, a very high fever of 104 °F or even 107.6 °F need to be cooled down, but in a healthcare facility. It is a myth that, if you exceed the temperature of 104 °F you are going to sustain severe brain damage, as long as the fever is treated properly and quickly by a physician.

• If I have a fever and take Tylenol, it should never reappear. If it does, it means that the drug is not working.

Taking medications to lower your fever provides relief, not cure. You are lowering your fever for some time so that you can feel better but the cause is not treated this way. When you have a fever and take some Tylenol, your fever will go down and then up again, at which point you will re-ingest a pill. This is the normal course of the symptom; it is not supposed to disappear once you take a pill. Make sure you are taking no more than the maximum dosage of a drug every day. If you need more, alternate it with a non-steroidal anti-inflammatory drug (NSAID such as Advil). Make sure you discontinue both if you show signs of an allergic reaction. If the fever does not respond to the medications, or if you need maximum doses of both, contact your doctor.