Table of ContentsView AllTable of ContentsSymptomsWhen to See a ProviderCausesTreatment

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View All

Table of Contents

Symptoms

When to See a Provider

Causes

Treatment

Most healthcare providers define a low-grade fever as a temperature between 99 degrees F (37.2 C) and 100.4 degrees F (38.0 C).A normal body temperature is typically described as 98.6 F (37 C) but can range from 97 F (36.1 C) to 99 F (37.2 C).

A low-grade fever is often the first sign of an infection. When the body temperature is normal, infectious bacteria and viruses are able to thrive. A fever is the body’s way of creating a hostile environment to help neutralize them.

Low-grade fevers also have non-infectious causes, including diseases, vaccines, and medications that affect the body’s “thermostat,” known as thehypothalamus.

This article explains the symptoms and causes of low-grade fevers. It also offers tips on how to manage a fever and when it is time to see a healthcare provider.

Low-Grade Fever Symptoms

Althoughfeveris the body’s defense against infection—increasing the internal temperature to where most bacteria and viruses are unable to survive—it can cause a cascade of symptoms the higher the temperature gets.

With a low-grade fever, the condition is oftenasymptomatic(without symptoms) or subclinical (not severe enough to cause definite or recognized symptoms). If symptoms do occur, they will often be mild and cause:

Low-Grade Fever in ChildrenA low-grade fever in children is between 99 F (37.2 C) and 100.3 F (37.9 C). If your child is 3 months or younger, call their healthcare provider if there is any fever, even a low-grade one. Fevers considered mild in adults can sometimes be a sign of a serious infection innewborns and infants.

Low-Grade Fever in Children

A low-grade fever in children is between 99 F (37.2 C) and 100.3 F (37.9 C). If your child is 3 months or younger, call their healthcare provider if there is any fever, even a low-grade one. Fevers considered mild in adults can sometimes be a sign of a serious infection innewborns and infants.

When to See a Healthcare Provider

There are times when a fever warrants a call to your healthcare provider or an immediate visit to the emergency room.

Adults

Seek medical care for a fever that appears with these other symptoms:

Fevers of any kind can be stressful. But it’s important to remember that most low-grade fevers are harmless and will run their course in a few days or less. Call your healthcare provider if you’re worried about symptoms or simply need advice or reassurance.

Infants and Children

Seek medical help right away if you child:

Call your child’s healthcare provider if:

Studies have shown that using touch to detect fever is unreliable. Up to 40% of people who try end up underestimating or entirely missing temperatures greater than 102 F (38.9 C).

What Causes a Low-Grade Fever?

A fever—even a low-grade one—is a sign that something is wrong in your body. It may indicate that your immune system is mounting a defense against a foreign invader like a virus or bacteria. Or, it may be due to non-infectious causes such as autoimmune diseases, medications, or even blood cancer.

Whatever the underlying cause, fever is ultimately the result of a trigger known as apyrogen. This is any substance from within or outside of the body that stimulates the production of a substance calledprostaglandinE2 (PGE2).

PGE2 acts on a part of the brain, called the hypothalamus, which regulates body temperature. It signals the hypothalamus to increase the temperature set point, causing the body to heat up.

Verywell / Theresa Chiechi

Infections That Can Cause a Low-Grade Fever

How the Immune System Keeps You Healthy

Infectious Causes

Viral, bacterial, parasitic, and fungal infections can all cause low-grade fevers. Some function independently as pyrogens (like viruses), while others release toxins that are pyrogenic (like bacteria).

Examples include:

Non-Infectious Illnesses

There are diseases and conditions that can directly or indirectly trigger a low-grade fever. These includeautoimmune diseases, hormonal disorders, inflammatory diseases, and conditions that cause the obstruction of major blood vessels or airways.

Certain medications can also trigger a low-grade fever, including:

Fever of Unknown OriginAn unexplained fever equal to or higher than 101 F (38.3 C) that is persistent or recurrent may be classified as a fever of unknown origin (FUO). An FUO can develop independently or end up being a sign of a serious condition likecancer.

Fever of Unknown Origin

An unexplained fever equal to or higher than 101 F (38.3 C) that is persistent or recurrent may be classified as a fever of unknown origin (FUO). An FUO can develop independently or end up being a sign of a serious condition likecancer.

Fever: What’s Considered Low, High, and Possibly Serious?

How to Treat a Low-Grade Fever

The general rule of thumb is to treat a low-grade fever only if it is causing discomfort. Some experts say that doesn’t happen until a temperature hits 102 F (38.9 C) or higher.

If you decide to treat a low-grade fever, over-the-counter painkillers likeTylenol (acetaminophen)and Advil (ibuprofen) 410 are good choices.

Other self-help measures include:

Should I Stay Home With a Fever?A low-grade fever may be a sign of a developing infection. The Centers for Disease Control and Prevention (CDC) advises you to stay at home for at least 24 hours if you have a fever of 100 F (37.8 C) or greater, even if you have no other symptoms.

Should I Stay Home With a Fever?

A low-grade fever may be a sign of a developing infection. The Centers for Disease Control and Prevention (CDC) advises you to stay at home for at least 24 hours if you have a fever of 100 F (37.8 C) or greater, even if you have no other symptoms.

How to Treat a Fever

Summary

A low-grade fever is between 99 degrees F (37.2 C) and 100.4 degrees F (38.0 C). It is usually nothing to worry about and will typically run its course in several days or less without treatment. Infections are the most common cause, but there are also non-infectious causes (including medications and stress).

Seek immediate medical care for a low-grade fever in children 3 months or under and anyone whose fever lasts for more than 72 hours.

A Word From VerywellA low-grade fever, while not as dangerous as a high-grade fever, comes with its own challenges. Keep things like understanding body temperature, temperature measurement methods, nutrition, and alcohol consumption in mind to ensure you or your loved ones stay safe and healthy.—KASHIF J. PIRACHA, MD, MEDICAL EXPERT BOARD

A Word From Verywell

A low-grade fever, while not as dangerous as a high-grade fever, comes with its own challenges. Keep things like understanding body temperature, temperature measurement methods, nutrition, and alcohol consumption in mind to ensure you or your loved ones stay safe and healthy.—KASHIF J. PIRACHA, MD, MEDICAL EXPERT BOARD

A low-grade fever, while not as dangerous as a high-grade fever, comes with its own challenges. Keep things like understanding body temperature, temperature measurement methods, nutrition, and alcohol consumption in mind to ensure you or your loved ones stay safe and healthy.

—KASHIF J. PIRACHA, MD, MEDICAL EXPERT BOARD

Kashif J. Piracha, MD

13 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Islam MA, Kundu S, Alam SS, Hossan T, Kamal MA, Hassan R.Prevalence and characteristics of fever in adult and paediatric patients with coronavirus disease 2019 (COVID-19): a systematic review and meta-analysis of 17515 patients.PLoS One. 2021;16(4):e0249788. doi:10.1371/journal.pone.0249788MedlinePlus.Body temperature norms.MedlinePlus.Fever.Walter EJ, Hanna-Jumma S, Carraretto M, Forni L.The pathophysiological basis and consequences of fever.Crit Care.2016;20:200. doi:10.1186/s13054-016-1375-5Zhuang SF, Hu J, Qiao N, et al.Low-grade fever during COVID-19 convalescence: a report of 3 cases.World J Clin Cases.2020;8(12):2655–61. doi:10.12998/wjcc.v8.i12.2655Barbi E, Marzuillo P, Neri E, Naviglio S, Krauss BS.Fever in children: pearls and pitfalls.Children (Basel).2017;4(9):81. doi:10.3390/children4090081Johns Hopkins Medicine.Fever.American Academy of Pediatrics.Fever: When to call the pediatrician.El-Radhi AS.Pathogenesis of fever.Clin Manual Fever Children.2019:53–68. doi:10.1007/978-3-319-92336-9_3Steele GM, Franco-Paredes C, Chastain DB.Non-infectious causes of fever in adults.Nurse Pract.2018;43(4):38-44. doi:10.1097/01.NPR.0000531067.65817.7dSeattle Children’s.Fever — myths versus facts.National Organization for Rare Disorders.Reye syndrome.Centers for Disease Control and Prevention.Stay home when you are sick.Additional ReadingDel Bene VE.Clinical Methods: The history, physical, and laboratory examinations.Chapter 218: Temperature. (3rd edition). Boston: Butterworths.

13 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Islam MA, Kundu S, Alam SS, Hossan T, Kamal MA, Hassan R.Prevalence and characteristics of fever in adult and paediatric patients with coronavirus disease 2019 (COVID-19): a systematic review and meta-analysis of 17515 patients.PLoS One. 2021;16(4):e0249788. doi:10.1371/journal.pone.0249788MedlinePlus.Body temperature norms.MedlinePlus.Fever.Walter EJ, Hanna-Jumma S, Carraretto M, Forni L.The pathophysiological basis and consequences of fever.Crit Care.2016;20:200. doi:10.1186/s13054-016-1375-5Zhuang SF, Hu J, Qiao N, et al.Low-grade fever during COVID-19 convalescence: a report of 3 cases.World J Clin Cases.2020;8(12):2655–61. doi:10.12998/wjcc.v8.i12.2655Barbi E, Marzuillo P, Neri E, Naviglio S, Krauss BS.Fever in children: pearls and pitfalls.Children (Basel).2017;4(9):81. doi:10.3390/children4090081Johns Hopkins Medicine.Fever.American Academy of Pediatrics.Fever: When to call the pediatrician.El-Radhi AS.Pathogenesis of fever.Clin Manual Fever Children.2019:53–68. doi:10.1007/978-3-319-92336-9_3Steele GM, Franco-Paredes C, Chastain DB.Non-infectious causes of fever in adults.Nurse Pract.2018;43(4):38-44. doi:10.1097/01.NPR.0000531067.65817.7dSeattle Children’s.Fever — myths versus facts.National Organization for Rare Disorders.Reye syndrome.Centers for Disease Control and Prevention.Stay home when you are sick.Additional ReadingDel Bene VE.Clinical Methods: The history, physical, and laboratory examinations.Chapter 218: Temperature. (3rd edition). Boston: Butterworths.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Islam MA, Kundu S, Alam SS, Hossan T, Kamal MA, Hassan R.Prevalence and characteristics of fever in adult and paediatric patients with coronavirus disease 2019 (COVID-19): a systematic review and meta-analysis of 17515 patients.PLoS One. 2021;16(4):e0249788. doi:10.1371/journal.pone.0249788MedlinePlus.Body temperature norms.MedlinePlus.Fever.Walter EJ, Hanna-Jumma S, Carraretto M, Forni L.The pathophysiological basis and consequences of fever.Crit Care.2016;20:200. doi:10.1186/s13054-016-1375-5Zhuang SF, Hu J, Qiao N, et al.Low-grade fever during COVID-19 convalescence: a report of 3 cases.World J Clin Cases.2020;8(12):2655–61. doi:10.12998/wjcc.v8.i12.2655Barbi E, Marzuillo P, Neri E, Naviglio S, Krauss BS.Fever in children: pearls and pitfalls.Children (Basel).2017;4(9):81. doi:10.3390/children4090081Johns Hopkins Medicine.Fever.American Academy of Pediatrics.Fever: When to call the pediatrician.El-Radhi AS.Pathogenesis of fever.Clin Manual Fever Children.2019:53–68. doi:10.1007/978-3-319-92336-9_3Steele GM, Franco-Paredes C, Chastain DB.Non-infectious causes of fever in adults.Nurse Pract.2018;43(4):38-44. doi:10.1097/01.NPR.0000531067.65817.7dSeattle Children’s.Fever — myths versus facts.National Organization for Rare Disorders.Reye syndrome.Centers for Disease Control and Prevention.Stay home when you are sick.

Islam MA, Kundu S, Alam SS, Hossan T, Kamal MA, Hassan R.Prevalence and characteristics of fever in adult and paediatric patients with coronavirus disease 2019 (COVID-19): a systematic review and meta-analysis of 17515 patients.PLoS One. 2021;16(4):e0249788. doi:10.1371/journal.pone.0249788

MedlinePlus.Body temperature norms.

MedlinePlus.Fever.

Walter EJ, Hanna-Jumma S, Carraretto M, Forni L.The pathophysiological basis and consequences of fever.Crit Care.2016;20:200. doi:10.1186/s13054-016-1375-5

Zhuang SF, Hu J, Qiao N, et al.Low-grade fever during COVID-19 convalescence: a report of 3 cases.World J Clin Cases.2020;8(12):2655–61. doi:10.12998/wjcc.v8.i12.2655

Barbi E, Marzuillo P, Neri E, Naviglio S, Krauss BS.Fever in children: pearls and pitfalls.Children (Basel).2017;4(9):81. doi:10.3390/children4090081

Johns Hopkins Medicine.Fever.

American Academy of Pediatrics.Fever: When to call the pediatrician.

El-Radhi AS.Pathogenesis of fever.Clin Manual Fever Children.2019:53–68. doi:10.1007/978-3-319-92336-9_3

Steele GM, Franco-Paredes C, Chastain DB.Non-infectious causes of fever in adults.Nurse Pract.2018;43(4):38-44. doi:10.1097/01.NPR.0000531067.65817.7d

Seattle Children’s.Fever — myths versus facts.

National Organization for Rare Disorders.Reye syndrome.

Centers for Disease Control and Prevention.Stay home when you are sick.

Del Bene VE.Clinical Methods: The history, physical, and laboratory examinations.Chapter 218: Temperature. (3rd edition). Boston: Butterworths.

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