Let's see if we can figure out what's causing your fever.
Select additional symptoms and we'll narrow your results.

What causes fever? 221 possible conditions

See a list of possible causes in order from the most common to the least.



This condition is considered a medical emergency. Urgent care may be required.

Appendicitis is inflammation of the appendix, which can be fatal if left untreated. The telltale sign is pain that usually starts as mild cramping, especially on the right side, and becomes more severe over time.

Read more »


Swine Flu

Swine flu, also known as H1N1, is a highly contagious virus with symptoms similar to common influenza types. It spreads quickly from person to person, and can linger on tables and surface areas.

Read more »



Tonsillitis occurs when the tonsils (the lymph tissue in your throat) become infected. Symptoms include sore throat, fever, and swollen tonsils. Fortunately, it's normally easily diagnosed and treated.

Read more »


Viral Gastroenteritis

Viral gastroenteritis, also known as the stomach flu, is caused by a number of different viruses. Its symptoms usually last for two to three days.

Read more »


Infectious Mononucleosis

Infectious mononucleosis, or "mono," is a group of symptoms caused by the Epstein-Barr virus. One potential symptom is a pink rash that looks like the measles.

Read more »



Pyelonephritis is an inflammation of the kidney and upper urinary tract. Symptoms include flushed skin, back pain, fever, and nausea.

Read more »


The Atypical Facts About Atypical Pneumonia

Pneumonia is an infection that causes inflammation of the lungs. Atypical pneumonia is a kind that isn't caused by the bacteria that causes typical pneumonia.

Read more »



Pharyngitis is inflammation of the pharynx, which is in the back of the throat. It's most often referred to simply as "sore throat" and is very common.

Read more »



Also known as varicella, chickenpox is a virus that often affects children. It is characterized by itchy, red blisters that appear all over the body.

Read more »



Cellulitis is a common, often painful skin infection that first appears as a red, swollen area that feels hot and tender to the touch. If left untreated, it can become life-threatening.

Read more »



This condition is considered a medical emergency. Urgent care may be required.

Epiglottitis is characterized by inflamed tissue in your epiglottis. It's a potentially life-threatening illness. The epiglottis is at the base of the tongue.

Read more »



Measles is a very contagious infection of the respiratory system. One of its several symptoms is a sore or swollen throat.

Read more »


The Many Sides of Bacterial Gastroenteritis

Bacterial infections are common causes of gastrointestinal infections. This type of infection is also called "food poisoning" and is often caused by poor hygiene or ingesting foods contaminated with bacteria.

Read more »


Crohn’s Disease

Crohn's disease is a chronic bowel disease that causes severe inflammation of the digestive tract. It is associated with abdominal pain, diarrhea, and may affect your quality of life. Crohn's disease is characterized b...

Read more »


Pelvic Inflammatory Disease (PID)

Pelvic inflammatory disease (PID) is an infection of the reproductive organs in women. It's marked by pain in the abdomen, especially during urination or sex.

Read more »


Fifth Disease

Fifth disease is caused by a virus and mostly affects children. The disease is marked by feeling unwell, often followed by a red rash on the cheeks.

Read more »


German Measles (Rubella)

German measles, also known as rubella, is a rare viral condition. One of its symptoms is a pink rash that begins on the face and spreads downward.

Read more »



An empyema is a condition in which pus collects in the pleural space, which is the area between your lungs and the inner surface of your chest wall.

Read more »



Rhinitis is inflammation of the nasal cavity lining (inside the nose). It is often caused by allergies. It may also be caused by environmental factors such as pollution, weather changes, stress, infections, and som...

Read more »


CFS (Chronic Fatigue Syndrome)

Chronic fatigue syndrome (CFS) is a debilitating disorder characterized by extreme tiredness that can't be explained by an underlying medical condition.

Read more »

This feature is for informational purposes only and should not be used to diagnose.
Please consult a healthcare professional if you have health concerns.