When is a fever dangerous? Know the warning signs

A fever isn’t always a problem. Defined as a temporary increase in body temperature, a fever is just a symptom, not an illness.

In fact, sometimes a fever can be a good thing: It’s often a sign that your body is fighting an infection or illness. But how do you know when a fever is dangerous? When is it time to see a doctor for a high temperature?

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Why You Have a Fever

A fever typically occurs in response to infection, when your body’s immune system is fighting off bacteria or a virus. People with autoimmune conditions (in which the body’s immune system attacks itself) can also experience fevers. Common causes of fever include:

In children, teething and immunizations may cause a slight fever for a day or two.

When to Seek Help: How to Know When a Fever Is Dangerous

You should seek medical attention for yourself or a child under the following fever scenarios:

  • If your child is 3 months old or younger and has a rectal temperature of 100.4 degrees F or higher
  • If your child is 3 to 12 months old and has an oral temperature of 102.2 degrees F
  • If your child is 2 years old or younger and has a fever that lasts longer than 24 to 48 hours
  • Adults with a fever higher than 105 degrees F or a fever over 103 degrees F that rises or lasts longer than 48 hours

In addition, you should seek medical care if you have a fever accompanied by rash and bruising, difficulty breathing, and/or pain while urinating. Also consult a doctor if you have recently been vaccinated, visited another country, or have a serious pre-existing illness. Seek out a pediatrician if your child seems confused, has a stiff neck, and/or won’t stop crying.

Learn more about complications of the fever

The Basics of Body Temperature

Normal body temperature is 98.6 degrees Fahrenheit, and anything above 99.5 F (when measured orally with a thermometer) is considered a fever in both children and adults.

Your body temperature can rise naturally throughout the day and is usually higher in the evening. A number of other factors can increase body temperature, but these factors are not considered fever-inducing. Things like physical exertion, heavy clothing, high humidity and heat, strong emotions, and certain medications can trigger your body temperature to rise. If you’re a woman on your menstrual cycle you may also experience a higher body temperature.

How to Lower a Fever

For most adults and kids with a mild fever under 102 degrees F, rest is the best solution. You can try to lower the fever yourself with some simple steps that work for both children and grownups:

  • Remove heavy clothing and blankets and keep surroundings cool but not cold
  • Take a lukewarm bath
  • Take acetaminophen as directed, but do not give young children aspirin
  • Drink plenty of fluids
  • Avoid ice baths and alcohol rubs, which can cause shivering and in turn raise body temperature further

Contact your primary care physician or visit a UPMC Urgent Care location if your fever persists.