Young woman with fever lying on couch and wondering whether inflammation can cause fever

Can inflammation cause fever?

Written on March 24, 2023 by Theresa Vuskovich, DMD. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

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Fever and inflammation go hand in hand. Inflammation occurs when your body is faced with an injury or an infection. Heat, redness, swelling, and pain are the signs of inflammation [1]. Heat can refer to a fever, a systemic elevation of body temperature [2]. So, can inflammation cause fever? Yes, a fever can occur in response to inflammation [1-4]. This article provides insight into fever and how inflammation causes fever.

What is a fever?

Fever is an elevation above normal body temperature. The average body temperature is 98.6°F (37°C), but everyone's body temperature varies slightly [2-4]. A person's body temperature is affected by age, medical conditions, location, and time of day [2-4].

You can check your body's temperature in several places, such as your mouth, forehead, ear, or armpits [2,3]. Your temperature is lower in the morning and rises throughout the day as you become active [2]. A fever is classified based on its duration and degree of elevation.

Fever classification

A fever is classified as acute, subacute, or chronic, depending on how long it lasts [4].

  • Acute fever: An acute fever occurs for less than seven days.
  • Sub-acute fever: A sub-acute fever occurs for less than two weeks.
  • Chronic fever: A chronic fever lasts longer than two weeks and can persist indefinitely.

Fevers are also categorized based on the degree of elevation [4].

  • Mild/low-grade fever: between 100.5–102.2°F
  • Moderate grade fever: between 102.2–104.0°F
  • High-grade fever between 104.1–106.0°F
  • Hyperpyrexia: equal to greater than 106.0°F

Fever causes

Below are some other common causes of fever [2-4]:

  • Viral infection: Viral infections are one of the most common causes of a fever. COVID-19 and the flu are common viral infections that lead to fever. Infections activate your immune system and create inflammation, resulting in fever.
  • Bacterial infection: Bacterial infections such as urinary tract infections or tooth abscesses can lead to a fever. As with viral infections, bacterial infections stimulate the immune system, creating inflammation and fever.
  • Drug reactions: Your body may produce fever when it perceives a drug as an invader. Common drugs that can cause fever include beta-lactam antibiotics (e.g., penicillin), procainamide, and sulfa drugs.
  • Immunizations: When you receive an immunization, the immune system becomes active and can create a fever. The influenza (flu) and COVID-19 vaccines are two of the most common vaccines associated with fever.
  • Autoimmune disorders: Autoimmune disorders create inflammation and fever within the body. Common autoimmune disorders that can cause fever include hyperthyroidism, lupus, and rheumatoid arthritis. Autoimmune disorders are often associated with low.
  • Undiagnosed cancer: Cancer creates inflammation leading to fever. Blood cancers such as leukemia are associated with fever.
  • Heat exhaustion: Excessive heat can cause heat exhaustion, causing your body to experience a fever because it cannot regulate its temperature.

Conditions with the word "fever"

Additionally, some conditions include the word “fever.”

Fever blisters: Fever blisters are commonly known as cold sores [5]. They are fluid-filled bumps around the mouth that eventually turn crusty. Herpes simplex virus (HPV) is responsible for fever blisters and can cause a fever [5].

Hay fever: Hay fever is another name for an allergic reaction to pollen or dust. There is no fever associated with hay fever.

Familial Mediterranean fever (FMF): People of Mediterranean origins, such as Iranians and Italians, are about 50% more likely to get this genetic disorder if they have a family history [6]. People with FMF have a gene mutation that makes their immune system less effective, resulting in recurrent fevers.

Fever of unknown origin (FUO): Someone with a fever of at least 101°F for several weeks without an obvious cause [7].

A fever does not always indicate a problem. A fever indicates that your immune system is actively fighting an infection rather than allowing it to win. People with low-grade to moderate fevers (acute fevers below 104° F) are generally not in danger unless the person is immunocompromised or experiencing severe fever symptoms [2].

Fever symptoms

Fevers can also cause other symptoms. Chills, tiredness, headaches, and muscle aches often occur when you have a fever. These symptoms are generally harmless. However, seek medical attention immediately if you have a fever and experience any of the following symptoms [2]:

  • Confusion or a change in mental function
  • Headache or stiff neck
  • Blood under the skin can appear as flat, small, purple spots (petechiae)
  • Low blood pressure (90/60 mm Hg)
  • High heart rate
  • Difficulty breathing
  • Temperature over 104°F or below 95°F

Everlywell can help with fevers and inflammation

Virtual care visits via Everlywell are available to address common conditions associated with fevers, including the flu and UTIs. Additionally, Everlywell's Vitamin D & Inflammation test provides insight into your body's inflammation levels. With Everlywell, you can monitor inflammation over time. Using your test results, your healthcare provider can create a customized care plan for you.

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  1. Hannoodee S, Nasuruddin DN. Acute Inflammatory Response. StatPearls Publishing; 2022. URL
  2. Bush LM. Fever in Adults. Merck Manuals Consumer Version. URL. Accessed March 7, 2023.
  3. Biology of infectious disease: Fever. Merck Manuals Professional Edition. URL. Accessed March 7, 2023.
  4. Ogoina D. Fever, fever patterns, and diseases called' fever'--a review. J Infect Public Health. 2011;4(3):108-124. doi:10.1016/j.jiph.2011.05.002. URL
  5. Fever blisters & canker sores. URL. Accessed March 8, 2023.
  6. Bhatt H, Cascella M. Familial Mediterranean Fever. StatPearls Publishing; 2022. URL
  7. Brown I, Finnigan NA. Fever of Unknown Origin. StatPearls Publishing; 2022. URL
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