Acute Fever

What is Acute Fever ?

The simplest definition of acute fever is it a sudden onset of an illness that attests with fever.  It is a symptom and not disease.

The body’s mechanism to respond to an infection causes fever. The infection could be viral or bacterial, and as a response, body increases the temperature of the blood that we know as fever. Nevertheless, it is difficult to diagnose the disease without knowing the presence of signs and symptoms other than fever.

Acute fever can happen to adults and kids, but it is more common in infants. In addition, acute fever could be mild, moderate or severe. In a healthy adult, mild acute fever could be transient and may subside without any harm. Nevertheless, high-grade fever (referred to as hyperpyrexia) or a persistent fever may require medical attention and intensive treatment as it indicates some serious underlying cause.

A sudden onset of fever makes a person feel down with a surprise that he or she was very well just a day back. If not associated with other signs and symptoms, acute fever (especially mild or moderate) does not bother the victim, as they feel normal otherwise. In most of the cases, one of the body systems (mentioned below) is involved in acute fever.

  1. Respiratory system (mainly upper respiratory tract)
  2. Digestive system (involving the gastrointestinal tract)
  3. Urogenital system (mainly urinary tract)
  4. Skin diseases

The symptoms of acute fever solely depend on which body system is involved. For instance, acute fever due respiratory tract infection may have malaise, cough or wheezing sound in the lungs in auscultation. While most of the acute fever are controllable, high-grade fever due to sepsis (septicemia) is a life-threatening condition that requires immediate treatment with hospitalization. Acute fever might be associated with pain and body ache especially in viral infections.

Acute Fever Medical Causes

The Causes of Infections help in understanding differential diagnosis of acute fever

As said earlier, the main cause of acute fever is an infection. Let us list common infection or condition sorted by body systems that help in understanding the differential diagnosis of acute fever.

Upper respiratory tract infection

The common conditions include acute sinusitis, tonsillitis etc. The symptoms include

  1. Running nose, nasal congestion, coughing (dry or with phlegm)
  2. Presence of pus (indicates that it is most probably due to bacterial infection)
  3. Sneezing and malaise
  4. Change in voice (referred to as xenophonia) and, as a result hoarseness
  5. Sore or burning throat
  6. Burning eyes, tired eyes
  7. Burning sensation in nose
  8. Difficulty in breathing (mainly due to congestion)
  9. Heaviness in the head
  10. Headache

Lower respiratory tract infection

The common conditions include bronchitis, pneumonia, lung disease (such as abscess), empyema etc. The common symptoms along with acute fever in this include

  1. Dry or cough with mucus
  2. Sputum with blood (requires immediate medical attention)
  3. Breathlessness (dyspnea)
  4. Abnormal breathing sounds (severe wheezing)
  5. Pain in chest
  6. Heaviness in thorax

Gastrointestinal tract infection

The common conditions in this section include gastroenteritis that could be due to viral or bacterial infection. The common symptoms other than acute fever include

  1. Nausea or vomiting
  2. Severe abdominal cramps
  3. Indigestion (diarrhea)
  4. Foul smell in flatulence
  5. Bloating
  6. Lethargy
  7. Weakness

Urinary tract infection (UTI)

The symptoms other than acute fever in the urinary tract infection include

  1. Painful micturition
  2. Dark urine (if it is blood, contact healthcare provider immediately)
  3. Burning sensation in urine
  4. Change in frequency of urination (either very frequent or very less)
  5. Urinary incontinence
  6. Pus discharge (if this is present, contact healthcare provider immediately)
  7. Severe tenderness in the pelvic region
  8. Retention of urine (may require surgical attention)

Skin diseases

some skin diseases may produce acute fever along with other signs and symptoms mentioned below…

  1. Itching at a particular site
  2. Burning sensation at the affected area or the whole body
  3. Redness or change in normal skin tone (color)
  4. Inflammation or swelling of skin
  5. Tenderness or pain at a particular site (may or may not be)
  6. Warmth (change in local temperature at the affected site)
  7. Appearance of boil, blister or something the like
  8. Formation of pus (especially in abscess)
  9. Frothing from the mouth, giddiness or even shock (in case of poison injection as in case of insect sting, animal bite or poisonous chemical/substance contact)

Drug induced acute fever

Some drugs can also produce mild to moderate fever as their side effects. Drug induced fever do not require specific treatment. When the causative drug is stopped, the fever subsides. Here is the list of the group of drugs that might produce pyrexia in individuals.

Acute fever as an allergic reaction to drug groups

  • Antiviral
  • Antifungal
  • Antibiotics
  • Anti-arrhythmic
  • Anti-epileptic
  • Chemotherapy

Narcotics can also produce mild to moderate fever

  • Ecstasy
  • Amphetamines
  • Cocaine

Other drugs such as anesthetics and antipsychotics may also raise the body temperature.

Miscellaneous causes

  1. Heat stroke
  2. High metabolic rate
  3. Excessive alcohol consumption
  4. Certain vaccination

Symptoms with Acute Fever

Acute fever is generally presented with other symptoms. We will now sort out the symptoms and list their probably causes…


  • Meningitis
  • Encephalitis
  • Endopthalmitis (tenderness behind the eyes)
  • Otitis media (stubborn ear infection)
  • Encephalitis

Pain in extremities

  • Impetigo
  • Cellulitis
  • Necrotizing fasciitis
  • Deep Vein Thrombosis (DVT)
  • Dengue
  • Chikungunya

Abdominal pain

  • Hepatitis
  • Appendicitis
  • Abscess in liver, ovaries, or pancreas
  • Infection in gallbladder (cholecystitis)
  • Infection in kidney (pyelonephritis)
  • Infection in intestines (colitis)
  • Diverticulitis
  • Typhoid
  • IBS

Chest pain

  • Koch’s disease
  • Empyema
  • Lung abscess
  • Pericarditis
  • Pulmonary embolism
  • Rheumatic fever

Acute hemorrhagic fever syndrome

This is the special condition wherein acute hemorrhagic fever syndromes are attributable to following conditions:

  • Dengue hemorrhagic fever
  • Ebola-Marburg viral disease
  • Lassa fever
  • Yellow fever
  • Rift Valley fever
  • Hantavirus infections
  • Crimean-Congo hemorrhagic fever

acute fever thermometer

Causes of Acute Fever in Children

In children, acute fever can be caused due to following conditions:Burns

  1. Infection
  2. Pharyngitis
  3. Bacteremia
  4. Urinary tract infection
  5. Roseola
  6. Croup
  7. Septic arthritis
  8. Rocky Mountain spotted fever
  9. Sinusitis
  10. Varicella
  11. Appendicitis
  12. Otitis media
  13. Septicemia
  14. Abscess
  15. Viral illnesses
  16. Cellulitis
  17. Gastroenteritis
  18. Erythema infectiosum (parvovirus B19)
  19. Bronchitis
  20. Meningococcemia
  21. Upper respiratory tract infection
  22. Tonsillitis
  23. Periorbital cellulitis
  24. Viral encephalitis
  25. Cat scratch disease
  26. Pyelonephritis
  27. Measles
  28. Parotitis
  29. Scarlet fever
  30. Trauma
  31. Myositis
  32. Herpangina
  33. Pneumonia (viral, bacterial, mycoplasma)
  34. Pertussis
  35. Dental abscess
  36. Vaccine reaction
  37. Bronchiolitis
  38. Herpes gingivostomatitis
  39. Kawasaki disease
  40. Meningitis (viral, bacterial)
  41. Drug reaction
  42. Infectious mononucleosis
  43. Hepatitis
  44. Hand-foot-mouth syndrome
  45. Sexually transmitted diseases
  46. Ostemyelitis
  47. Lymphadenitis

Diagnosing Acute Fever

The diagnosis depends upon the cause. In most of the cases, hemogram (complete blood test) is advised. A thorough physical examination, auscultation, palpation along with patient’s history helps in diagnosing the condition of acute fever. ESR, smear for parasites (mainly for malaria), blood culture, typhoid test (WIDAL), urine routine and micro etc. help in finding the exact cause of acute fever. In some cases X-Ray chest and ultrasound is carried out to check the health of the internal organs. In conditions like meningitis, the fluid (spinal) is preferred for microscopic study.

Treatment and Remedy for Acute Fever

While in most of the cases of acute fever, treatment remains symptomatic, but in treatment of acute rheumatic fever requires special attention. Firstly, the patient is asked to take absolute rest until the symptoms of inflammation pass. At earliest, sedative drugs and cardiac tonics are resorted, and daily heart check-up is preferred. The salts of salicylic acid are preferred to alleviate the pain and fever. Nevertheless, to overcome these drugs’ side effects (such as gastrointestinal irritation), certain anti-emetic and anti-acidity drugs can be combined in treatment.

In general practice of medicine, three main drugs mentioned below are used to treat fever.

  1. Acetaminophen (paracetamol) is the preferred drug to reduce the body temperature. As compared to other drugs, it is safe to use in pediatric cases. The recommended dose is suggested by child specialist. Adults can take this drug according to physician’s advice. Acetaminophen is contraindicated in patients with liver dysfunction and thus requires specific medical attention.
  2. Ibuprofen is another drug of choice to bring down the body temperature. Nevertheless, it is prescribed to the patients over 6 months (in infants, it is contraindicated). Recommended dosage is decided by the physician.
  3. For children and teenagers, feverish condition is treated using aspirin. Especially in case of viral fever (for instance influenza, chickenpox etc.), aspirin is a drug of choice to reduce fever.

Other than drugs, the condition of fever can be lessened by asking the patient to dress comfortably. Overdressing may contribute in rising the body temperature. Tepid water bath is one of the best natural remedies to get rid of fever. Cold water sponging is advised in individuals with high fever.

Herbs as natural therapy to reduce body temperature

Herbs from the genus Angelica (Family: Apiaceae) have been used traditionally as anti-inflammatory, pyretic and diaphoretic (Curr. Med Chem. 2004 Jun; 11(11):1479-500). Andrographis paniculata for fever is used in Chinese and Indian traditional medical practice as primary treatment (J Ethnobiol Ethnomed. 2010 Dec 13; 6:35. doi: 10.1186/1746-4269-6-35). In Ayurveda (holistic Indian Medicine), leaves of Abies pindrow Royle are prescribed as natural anti-pyretic remedy (Afr J Tradit Complement Altern Med. 2011; 8(4):391-7. Epub 2011 Jun 1).


  4. National Journal of Pediatrics
  5. eMedicineNet
  6. Wikipedia
  7. MayoClinic
  8. IndianPediatrics.Net

Published by Dr. Raj MD under Diseases and Conditions.
Article was last reviewed on August 6th, 2018.

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