A fever is a temporary rise in body temperature. A fever by itself is not an illness, but a symptom of a range of medical conditions and part of an overall response by the body’s immune system, usually caused by an infection. Fevers can also be a side effect of some medications.  

Fevers are broadly categorized as low-grade, moderate-grade, high-grade, and hyperpyrexia. 

Low-grade fever is an oral temperature of 99.1°F to 100.4°F (37.3°C to 38°C) in adults. Symptoms of a low-grade fever include: 

• Headache  

• Feeling hot 

• Achy eyes 

• Loss of appetite 

• Thirst  

Moderate fever is an oral temperature of 100.6°F to 102.2°F (38.1°C to 39°C) in adults. Symptoms of a moderate-grade fever are like those of a low-grade fever, but also include: 

• Muscle and body aches 

• Fatigue 

• Sweating 

• Dizziness or lightheadedness 

• Nausea  

High-grade fever is an oral temperature of 102.4°F to 105.8°F (39.1°C to 41°C) in adults. Symptoms of a high-grade fever are like those of a low-grade and moderate-grade fever, but also include: 

• Increased heart rate 

• Chills and shivering 

• Upset stomach 

• Extreme weakness 

• Vomiting 

• Decreased urination 

Hyperpyrexia is an extremely high fever of over 106.7°F (41.5°C). 

Symptoms of hyperpyrexia include: 

• Hallucinations 

• Extreme confusion 

• Rapid but weak heartbeat 

• Loss of consciousness 

• Shallow, rapid breathing 

• Dilated pupils 

• Seizures 

• Hot, dry, red skin 

• Inability to urinate 

Fevers, such as low-grade fevers, don’t always require a hospital visit, as they often improve with medication and home care. However, moderate- or high-grade fever can be dangerous, especially if accompanied by other symptoms. If your fever reaches 105°F (40.5°C), seek medical attention immediately. 

Adults should seek care from their healthcare provider if: 

• They have a fever of 104°F (40°C) or higher 

• They are over 65 years of age or immunocompromised, and their fever is higher than 101°F (38.3°C) 

• They have swelling or severe pain anywhere in their body 

• They have a stiff neck 

• They have trouble breathing 

For infants and young children, it is smart to be cautious and seek medical care if their symptoms are concerning, regardless of the temperature reading on the thermometer. You should take your child to receive medical care if: 

• Your child is three to 12 months and has a fever of 102.2°F (39°C) 

• Your child is younger than three months and has a fever of 100.4°F (38°C) or higher 

• Your child is older than 12 months and has a fever above 104°F (40°C) 

• Your child is under the age of two and has a fever that has lasted longer than 24 hours 

• Your child is over the age of two and has a fever that has lasted longer than three days 

• Your child’s symptoms are getting worse 

• Your child still appears to be sick after taking fever-reducing medication 

• A child who has not had immunizations or did not get timely immunizations with a temperature of 100.4°F or above 

There are several ways to reduce a fever, such as over-the-counter fever reducers like acetaminophen or ibuprofen, resting and drinking plenty of fluids, and taking a lukewarm bath. 

If you or your child is experiencing moderate- or high-grade fever symptoms, you can schedule an appointment with a physician at Jamaica Hospital Medical Center’s Ambulatory Care Center. Please call (718) 206-7001. 

All content of this newsletter is intended for general information purposes only and is not intended or implied to be a substitute for professional medical advice, diagnosis or treatment. Please consult a medical professional before adopting any of the suggestions on this page. You must never disregard professional medical advice or delay seeking medical treatment based upon any content of this newsletter. PROMPTLY CONSULT YOUR PHYSICIAN OR CALL 911 IF YOU BELIEVE YOU HAVE A MEDICAL EMERGENCY.