Fever
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Try one of these related symptoms.
Have a fever
My body is hot
Recurrent fevers
Periodic fever (>100.4°F / 38°C)
Fever then no fever then fever again
Remittent fever of 102.2°F / 39°C
Extremely high fever of 106.7°F / 41.5°C or higher
Fever of 100.4°F / 38°C or more for weeks
Stomach was uncomfortable, then had a fever
Stomachache and diarrhea before a fever
Temperature of 102.2°F / 39°C goes up and down
About the Symptom
A fever is a rise in body temperature.
When to See a Doctor
Seek professional care if you experience any of the following symptoms
- Repeated fever above 38 ℃
- Difficulty breathing / breathlessness
- Gross hematuria
- Peripheral cyanosis
- Sensation of incomplete voiding
- Respiratory wheeze
- Seizure attack
Possible Causes
Generally, Fever can be related to:
- Adult Still's Disease
A rare systemic inflammatory disease characterized by high fevers, a pink rash, sore throat and body aches that persist for weeks. The exact cause is unknown but is thought to be triggered by an infection. Some patients will have only one episode of it, while others may have several recurrent episodes.
- Acute Disseminated Encephalomyelitis
Acute disseminated encephalomyelitis involves widespread inflammation of the brain and spinal cord, resulting in damage to nerve fibers and their protective linings. It is a result of inflammation that occurs after after an infection or immunization. While it can affect anyone it is more common in children.
- Rabies
Rabies is a deadly viral disease that can spread to people and animals through bites or scratches from infected animals. It is commonly found in wild animals like stray dogs, bats, raccoons, skunks, and foxes. The rabies virus travels through nerve cells to the brain, where it multiplies quickly, causing severe inflammation of the brain and spinal cord, often leading to death.
- Suppurative Lymphadenitis
Related Serious Diseases
Sometimes, Fever may be related to these serious diseases:
- Spinal Cord Abscess
A buildup of pus around the spinal cord can compress nerves and cause symptoms. This sometimes occurs when bacteria from nearby wounds invade, or when bacteria multiply in distant areas and travel through the bloodstream to the spinal cord's surface.
- Peritonitis
- Empyema
- Malaria
- Measles
- Viral Associated Hemophagocytic Syndrome
Doctor's Diagnostic Questions
Your doctor may ask these questions to check for this symptom:
- Do you have a fever?
- When did you first notice the fever?
- During your fever, what is your highest body temperature?
- How is your fever now?
- Do you have recurrent fever episodes?
Reviewed By:
Yoshinori Abe, MD (Internal Medicine)
Dr. Abe graduated from The University of Tokyo School of Medicine in 2015. He completed his residency at the Tokyo Metropolitan Health and Longevity Medical Center. He co-founded Ubie, Inc. in May 2017, where he currently serves as CEO & product owner at Ubie. Since December 2019, he has been a member of the Special Committee for Activation of Research in Emergency AI of the Japanese Association for Acute Medicine. | | Dr. Abe has been elected in the 2020 Forbes 30 Under 30 Asia Healthcare & Science category.
Unnati Patel, MD, MSc (Family Medicine)
Dr.Patel serves as Center Medical Director and a Primary Care Physician at Oak Street Health in Arizona. She graduated from the Zhejiang University School of Medicine prior to working in clinical research focused on preventive medicine at the University of Illinois and the University of Nevada. Dr. Patel earned her MSc in Global Health from Georgetown University, during which she worked with the WHO in Sierra Leone and Save the Children in Washington, D.C. She went on to complete her Family Medicine residency in Chicago at Norwegian American Hospital before completing a fellowship in Leadership in Value-based Care in conjunction with the Northwestern University Kellogg School of Management, where she earned her MBA. Dr. Patel’s interests include health tech and teaching medical students and she currently serves as Clinical Associate Professor at the University of Arizona School of Medicine.
Content updated on Jan 29, 2025
Following the Medical Content Editorial Policy
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People with similar symptoms also use Ubie's symptom checker to find possible causes
- Has over 100.4°F / 38°C heat
- Persistently having fever of 102.2°F / 39°C for a whole day and it spikes even higher once in a while
- Fever subsided to normal temperatures for a while but came back again
- Persistent fever of 100.4°F / 38°C or more for more than 7 days
- Baby has a fever but is otherwise healthy and energetic
- Fever is going too high, 106.7°F / 41.5°C or higher
- Keep getting high temperatures (>100.4°F / 38°C)
- Coughing and runny nose before the fever started
- There is a slight fever
- Fever of 102.2°F / 39°C goes up and down but it doesn't disappear
- Recovered from fever for a few days but the fever is back
- Continuous fever of 100.4°F / 38°C or more for a week
- Child has a fever but seems in good health still
- Get high fevers so often (>100.4°F / 38°C)
- High body temperature
See full list
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FAQs
Q.
How many days does fever last after COVID-19 infection?
A.
Following COVID infection, it is common for a fever of 38℃/100.4°F or higher to last for anywhere from 2-10 days.
References:
Tavakolifard N, Moeini M, Haddadpoor A, Heidari K, Rezaee M, Amini Z. Clinical Symptoms of COVID-19 and Their Association with Disease Outcome. Adv Biomed Res. 2022 Jan 31;11:2. doi: 10.4103/abr.abr_79_21. PMID: 35284355; PMCID: PMC8906090.
Q.
What could be causing recurrent fevers in adults at night?
A.
Recurring fevers at night in adults may be caused by many different things like cancers, infections and autoimmune diseases.
References:
Unger M, Karanikas G, Kerschbaumer A, Winkler S, Aletaha D. Fever of unknown origin (FUO) revised. Wien Klin Wochenschr. 2016 Nov;128(21-22):796-801. doi: 10.1007/s00508-016-1083-9. Epub 2016 Sep 26. PMID: 27670857; PMCID: PMC5104815.
Q.
What are the symptoms of fever post-COVID?
A.
Post-COVID, some individuals may experience lingering symptoms, including fever. This condition, often referred to as "long COVID," can present with a variety of symptoms that may persist for weeks or months after the initial infection.
References:
Aiyegbusi OL, Hughes SE, Turner G, Rivera SC, McMullan C, Chandan JS, Haroon S, Price G, Davies EH, Nirantharakumar K, Sapey E, Calvert MJ; TLC Study Group. Symptoms, complications and management of long COVID: a review. J R Soc Med. 2021 Sep;114(9):428-442. doi: 10.1177/01410768211032850. Epub 2021 Jul 15. PMID: 34265229; PMCID: PMC8450986.
Tan S, Pryor AJG, Melville GW, Fischer O, Hewitt L, Davis KJ. The lingering symptoms of post-COVID-19 condition (long-COVID): a prospective cohort study. Intern Med J. 2024 Feb;54(2):224-233. doi: 10.1111/imj.16251. Epub 2023 Nov 26. PMID: 38008902.
Davis HE, McCorkell L, Vogel JM, Topol EJ. Long COVID: major findings, mechanisms and recommendations. Nat Rev Microbiol. 2023 Mar;21(3):133-146. doi: 10.1038/s41579-022-00846-2. Epub 2023 Jan 13. Erratum in: Nat Rev Microbiol. 2023 Jun;21(6):408. doi: 10.1038/s41579-023-00896-0. PMID: 36639608; PMCID: PMC9839201.
Q.
How long does it take for tylenol (acetaminophen) to start working?
A.
Tylenol, or acetaminophen, is a commonly used over-the-counter medication for pain relief and fever reduction. It takes about 30-60 minutes to start working after taking it.
References:
Shinoda S, Aoyama T, Aoyama Y, Tomioka S, Matsumoto Y, Ohe Y. Pharmacokinetics/pharmacodynamics of acetaminophen analgesia in Japanese patients with chronic pain. Biol Pharm Bull. 2007 Jan;30(1):157-61. doi: 10.1248/bpb.30.157. PMID: 17202677.
Hakim M, Anderson BJ, Walia H, Tumin D, Michalsky MP, Syed A, Tobias JD. Acetaminophen pharmacokinetics in severely obese adolescents and young adults. Paediatr Anaesth. 2019 Jan;29(1):20-26. doi: 10.1111/pan.13525. Epub 2018 Nov 28. PMID: 30484909.
Forrest JA, Clements JA, Prescott LF. Clinical pharmacokinetics of paracetamol. Clin Pharmacokinet. 1982 Mar-Apr;7(2):93-107. doi: 10.2165/00003088-198207020-00001. PMID: 7039926.
Q.
If I have a fever, should I see primary care? Guidelines for when to seek medical attention.
A.
Fever is a common symptom that can indicate an underlying infection or illness. Whether or not to seek medical attention for a fever depends on several factors, including the severity of the fever, accompanying symptoms, and the duration of the fever.
References:
Sandoughi M, Fazeli SA, Naseri-Ramroudi F, Barzkar F. Best Practice for Prolonged Fever in Primary Care Setting: Close Follow-Up or Empiric Antibiotic Therapy? Korean J Fam Med. 2018 Sep;39(5):318-321. doi: 10.4082/kjfm.17.0118. Epub 2018 Jul 4. PMID: 29972895; PMCID: PMC6166114.
Eskerud JR, Laerum E, Fagerthun H, Lunde PK, Naess A. Fever in general practice. I. Frequency and diagnoses. Fam Pract. 1992 Sep;9(3):263-9. doi: 10.1093/fampra/9.3.263. PMID: 1459379.
de Bont EG, Lepot JM, Hendrix DA, Loonen N, Guldemond-Hecker Y, Dinant GJ, Cals JW. Workload and management of childhood fever at general practice out-of-hours care: an observational cohort study. BMJ Open. 2015 May 19;5(5):e007365. doi: 10.1136/bmjopen-2014-007365. PMID: 25991452; PMCID: PMC4442146.
Q.
How long does extra strength tylenol last?
A.
Extra Strength Tylenol, which contains acetaminophen, typically provides pain relief for about 4 to 6 hours after taking a dose. However, the duration of its effectiveness can vary based on individual factors such as metabolism, dosage, and the specific type of pain being treated.
References:
Ohashi N, Kohno T. Analgesic Effect of Acetaminophen: A Review of Known and Novel Mechanisms of Action. Front Pharmacol. 2020 Nov 30;11:580289. doi: 10.3389/fphar.2020.580289. PMID: 33328986; PMCID: PMC7734311.
Sobieraj DM, Baker WL, Martinez BK, et al. Comparative Effectiveness of Analgesics To Reduce Acute Pain in the Prehospital Setting [Internet]. Rockville (MD): Agency for Healthcare Research and Quality (US); 2019 Sep. (Comparative Effectiveness Review, No. 220.) Table 1, Onset, duration, and typical initial doses for analgesicsa
https://www.ncbi.nlm.nih.gov/books/NBK546195/table/ch2.tab1/
Q.
Can I take acetaminophen (Tylenolⓡ) and ibuprofen (Advilⓡ) together?
A.
Yes, you can take acetaminophen (Tylenol®) and ibuprofen (Advil®) together safely. This combination can be effective for managing pain and reducing fever, but it is important to follow recommended dosages and consult a healthcare professional if you have any concerns.
References:
Aitken P, Stanescu I, Playne R, Zhang J, Frampton CMA, Atkinson HC. An integrated safety analysis of combined acetaminophen and ibuprofen (Maxigesic ® /Combogesic®) in adults. J Pain Res. 2019 Feb 8;12:621-634. doi: 10.2147/JPR.S189605. PMID: 30804681; PMCID: PMC6371943.
Derry CJ, Derry S, Moore RA. Single dose oral ibuprofen plus paracetamol (acetaminophen) for acute postoperative pain. Cochrane Database Syst Rev. 2013 Jun 24;2013(6):CD010210. doi: 10.1002/14651858.CD010210.pub2. PMID: 23794268; PMCID: PMC6485825.
Paul IM, Sturgis SA, Yang C, Engle L, Watts H, Berlin CM Jr. Efficacy of standard doses of Ibuprofen alone, alternating, and combined with acetaminophen for the treatment of febrile children. Clin Ther. 2010 Dec;32(14):2433-40. doi: 10.1016/j.clinthera.2011.01.006. PMID: 21353111; PMCID: PMC3614072.
Q.
Is the maximum dose of acetaminophen (tylenol®) 500mg in 24 hours?
A.
No, the maximum dose of acetaminophen (Tylenol®) is not 500 mg in 24 hours. The typical maximum dose for adults is generally 3,000 to 4,000 mg per day, depending on individual health factors and specific product guidelines.
References:
PDQ Supportive and Palliative Care Editorial Board. Pain (PDQ®): Health Professional Version. 2015 Jul 16. In: PDQ Cancer Information Summaries [Internet]. Bethesda (MD): National Cancer Institute (US); 2002-.
https://www.ncbi.nlm.nih.gov/books/NBK65949.1/
IARC Working Group on the Evaluation of Carcinogenic Risks to Humans. Pharmaceutical Drugs. Lyon (FR): International Agency for Research on Cancer; 1990. (IARC Monographs on the Evaluation of the Carcinogenic Risks to Humans, No. 50.) Paracetamol (Acetaminophen)
Q.
Is it okay to take tylenolⓡ with a fever of 99°f?
A.
Fever alone is not necessarily harmful. However, taking a medication like TylenolⓇ (acetaminophen) is a good option if you aren’t feeling well due to the fever.
References:
Bernheim HA, Block LH, Atkins E. Fever: pathogenesis, pathophysiology, and purpose. Ann Intern Med. 1979 Aug;91(2):261-70. doi: 10.7326/0003-4819-91-2-261. PMID: 223485.
Wright WF, Auwaerter PG. Fever and Fever of Unknown Origin: Review, Recent Advances, and Lingering Dogma. Open Forum Infect Dis. 2020 May 2;7(5):ofaa132. doi: 10.1093/ofid/ofaa132. PMID: 32462043; PMCID: PMC7237822.
Dinarello CA, Wolff SM. Molecular basis of fever in humans. Am J Med. 1982 May;72(5):799-819. doi: 10.1016/0002-9343(82)90548-4. PMID: 6805324.
Q.
What could be the causes of diarrhea and fever at the same time?
A.
Infectious gastroenteritis caused by bacteria and viruses is a likely and common cause of those symptoms.
References:
Graves NS. Acute gastroenteritis. Prim Care. 2013 Sep;40(3):727-41. doi: 10.1016/j.pop.2013.05.006. Epub 2013 Jul 19. PMID: 23958366; PMCID: PMC7119329.
Q.
What could be the possible causes if you are experiencing fever and headache at the same time?
A.
Headache and fever at the same time can be from a wide range of things: the benign (common cold) to the more serious (bacterial meningitis, brain tumor).
References:
Do TP, Remmers A, Schytz HW, Schankin C, Nelson SE, Obermann M, Hansen JM, Sinclair AJ, Gantenbein AR, Schoonman GG. Red and orange flags for secondary headaches in clinical practice: SNNOOP10 list. Neurology. 2019 Jan 15;92(3):134-144. doi: 10.1212/WNL.0000000000006697. Epub 2018 Dec 26. PMID: 30587518; PMCID: PMC6340385.
Q.
What happens if you take too much acetaminophen (Tylenolⓡ)?
A.
The toxic range of acetaminophen (7500-15000mg) is much higher than the recommended one time dose range for an adult (1000mg). Most people do not have symptoms in the first 24 hours. If you are concerned you took too much acetaminophen, seek further medical evaluation.
References:
Fisher ES, Curry SC. Evaluation and treatment of acetaminophen toxicity. Adv Pharmacol. 2019;85:263-272. doi: 10.1016/bs.apha.2018.12.004. Epub 2019 Jan 22. PMID: 31307590.
LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet]. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; 2012-. Acetaminophen. [Updated 2016 Jan 28].
Q.
What is the recommended dosage of acetaminophen ?
A.
While general dosing guidelines are on packaging, it is important to remember that dosing varies on weight, indication and other underlying diseases.
References:
Ameer B, Greenblatt DJ. Acetaminophen. Ann Intern Med. 1977 Aug;87(2):202-9. doi: 10.7326/0003-4819-87-2-202. PMID: 329728.
Ayoub SS. Paracetamol (acetaminophen): A familiar drug with an unexplained mechanism of action. Temperature (Austin). 2021 Mar 16;8(4):351-371. doi: 10.1080/23328940.2021.1886392. PMID: 34901318; PMCID: PMC8654482.
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https://www.medrxiv.org/content/10.1101/2024.08.29.24312810v1References
High temperature (fever) in adults
https://www.nhs.uk/conditions/fever-in-adults/