How to Tell if You Have a Fever

Last Updated: March 11, 2022 References Approved

A fever is the body's natural response to an underlying condition generally caused by a virus, infection, or another malady. A fever raises the body's internal temperature to create an inhospitable environment for the bug, which usually dies off within a matter of days. Generally, any temperature over 100.4 °F (38.0 °C) is considered a fever. This article will help self-identify a fever as well as give you advice about how to follow should the fever present a more serious medical situation.

Method 1

Method 1 of 2:

Diagnosing Fever

1
Take your temperature if you have a thermometer. If your temperature is 103°F (39.4°C) or lower, try to treat the fever at home, seeing whether it responds to at-home care.^{[1]
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Research source} If it's 104°F or higher, call emergency services or go straight to the emergency room; you may need immediate medical attention.
- If your temperature has been 103 °F (39 °C) for at least 3 days, call your doctor.
2
Try to feel the skin of the person in question. If the person's skin feels very hot to the touch, they are likely running a fever. Using this method, though, it's going to be hard to tell whether your temperature is at 98.7 °F (37.1 °C) or at 101.2 °F (38.4 °C). If the person feels hot to the touch, look for other symptoms or pick up a thermometer from a drug store to see if medical intervention may be necessary.

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3
Check for signs of dehydration. A fever happens when your body raises its internal temperature in order to ward off harmful infections, viruses, or other maladies.^{[2]
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Research source} Some research has even found that certain immune cells work better at these elevated temperatures. It's a natural defense mechanism. One significant result of this switching on of the body's heat switch is that patients can get or feel dehydrated.
- Signs^{[3]
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  Research source} that you may be dehydrated include:
  - Dry mouth
  - Thirst
  - Headache and fatigue
  - Dry skin
  - Constipation
- Dehydration can be made even worse if it is accompanied by vomiting or diarrhea.^{[4]
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  Research source} If you've experienced any one of these, especially, be sure to drink plenty of fluids to compensate for their loss. If you're struggling to drink fluids, try eating ice chips.
4
Check for muscle aches. In many cases, muscle aches are associated with dehydration, but they can be especially aggravating in a patient with the fever. Note: If your fever presents with back or muscle stiffness, call a doctor right away, as your condition may be related to a number of complications including kidney issues or bacterial meningitis, which can potentially cause brain damage.
5
Look for especially bad signs of a fever. If your fever is at or above 104°F (40°C), you could experience some of the following in addition to hot flashes, dehydration, headaches, muscle aches, and general weakness. If you do experience any of the following, or have cause to believe that your fever is above 104°F, see a doctor immediately^{[5]
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Research source}:
- Hallucination
- Confusion or irritability
- Convulsions or seizures
6
When in doubt, see a doctor. If you are dealing with a child who potentially has a fever, and whose temperature clocks in at higher than 103°F (39.4°C), see a doctor. In most cases, treating mild or moderate fevers at home is completely acceptable; in few cases, the underlying reason for the fever may demand serious medical attention.
- If you have a high fever or if your symptoms impact your ability to function, call a friend or family member and ask them to escort you to the doctor's office. It's not worth the risk of trying to get yourself there when you're in a compromised state.

Method 2

Method 2 of 2:

Getting Basic Treatment for Fever

1
Understand that for low-grade (mild) fevers, some doctors recommend letting the fever run its course. A fever is a body's natural response to a foreign body. Breaking the fever before the body has had time to attack the foreign body may prolong the illness or mask other symptoms associated with the fever.^{[6]
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Research source}
2
Take an OTC pain medication. An over-the-counter pain medication, like an NSAID or acetaminophen, can help reduce a fever.^{[7]
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Expert Source

David Nazarian, MD
Diplomate, American Board of Internal Medicine
Expert Interview. 26 March 2020.} Often, low doses of NSAIDs produce good results.
- Aspirin is for adults only. Aspirin given to children has been linked to a dangerous condition called Reye's Syndrome.^{[8]
  X
  Research source} It is therefore advisable only to administer aspirin as an adult.
- Acetaminophen (Tylenol) or ibuprofen (Advil) are acceptable substitutes for all ages. If your temperature remains high even after the recommended dose, don't take more; instead, consult a doctor.
3
Drink plenty of fluids. Drinking enough fluids can help decrease your fever.^{[9]
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Expert Source

David Nazarian, MD
Diplomate, American Board of Internal Medicine
Expert Interview. 26 March 2020.} Fluids are essential for fevers because they reduce the risk of dehydration, a serious concern during fevers. Stick mostly to water if experiencing a fever. Sodas and teas, in moderation, may help calm the stomach. Try to eat lukewarm soups and other liquid broths in addition to more solid foods. Popsicles may also help, and provide a cooling sensation in the process.
- Dehydration may exacerbate a fever if left untreated.

Expert Q&A

Question

How can I treat a fever?

David Nazarian, MD
Diplomate, American Board of Internal Medicine
Dr. David Nazarian is a board certified Internal Medicine Physician and the Owner of My Concierge MD, a medical practice in Beverly Hills California, specializing in concierge medicine, executive health and integrative medicine. Dr. Nazarian specializes in comprehensive physical examinations, IV Vitamin therapies, hormone replacement therapy, weight loss, platelet rich plasma therapies. He has over 16 years of medical training and facilitation and is a Diplomate of the American Board of Internal Medicine. He completed his B.S. in Psychology and Biology from the University of California, Los Angeles, his M.D. from the Sackler School of Medicine, and a residency at Huntington Memorial Hospital, an affiliate of the University of Southern California.

David Nazarian, MD

Diplomate, American Board of Internal Medicine

Expert Answer

You can take an over-the-counter medication like Advil, Aleve, or Tylenol to decrease your fever and help with your symptoms. Remember to drink plenty of fluids as well. You can also take a cold bath or shower to lower your fever.
Question

I have a humongous headache, my legs are sore, I feel like I haven't drunk water in weeks. I don't have a thermometer and my dad he is Hispanic, so he believes it will just go away. I didn't know what to do. Does this mean I have a fever? I also get chill, I always want to be in my blankets.

Marsha Durkin, RN
Registered Nurse
Marsha Durkin is a Registered Nurse and Laboratory Information Specialist for Mercy Hospital and Medical Center in Illinois. She received her Associates Degree in Nursing from Olney Central College in 1987.

Marsha Durkin, RN

Registered Nurse

Expert Answer

Please see your doctor asap as it sounds like you are feeling pretty ill and might need medical care.
Question

Is it normal to have a stomach ache when you have a fever?

Marsha Durkin, RN
Registered Nurse
Marsha Durkin is a Registered Nurse and Laboratory Information Specialist for Mercy Hospital and Medical Center in Illinois. She received her Associates Degree in Nursing from Olney Central College in 1987.

Marsha Durkin, RN

Registered Nurse

Expert Answer

Yes, you can have a stomach ache with a fever.

Warnings

If you have a fever for more than 48 hours (in general), without it going down, go to your doctor.

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If you feel dizzy and can't really stand up, wait till you feel better before you walk around.

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If the fever is at or above 104 °F (40 °C) for an adult, 103 °F (39 °C) for a child, or 100.4 °F (38.0 °C) for an infant, seek urgent medical care.

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