Types of Fever | Causes, Symptoms, Diagnosis & Treatment Explained

Types of Fever: Fever is a common medical condition characterized by a temporary rise in body temperature, often as a response to infections or underlying health issues. It is not a disease itself but a symptom indicating that the body is fighting an illness. 

There are different types of fever, each varying in cause, duration, and severity. Some common types include intermittent fever, remittent fever, continuous fever, and relapsing fever. Identifying the type of fever helps in proper diagnosis and treatment. Understanding fever symptoms, causes, and treatment options can aid in better health management and faster recovery.

What is Fever?

Fever is a temporary increase in body temperature, usually above 98.6°F (37°C), indicating that the body's immune system is actively fighting an infection or illness. It is not a disease but a symptom of an underlying condition, such as a viral or bacterial infection. A mild fever is generally harmless and can help the body recover, but a high or prolonged fever may require medical attention. Understanding the causes, types, and symptoms of fever is essential for proper management and treatment.

What Causes Fever?

Fever occurs when the body's internal thermostat, controlled by the hypothalamus, raises the temperature in response to certain triggers. Common causes of fever include:

• Infections – Viral or bacterial infections like the flu, cold, pneumonia, or COVID-19.
• Inflammatory Conditions – Diseases such as arthritis or autoimmune disorders.
• Heat Exhaustion – Overheating due to excessive exposure to heat or sun.
• Certain Medications – Some drugs, including antibiotics and vaccines, may trigger fever.
• Serious Illnesses – Conditions like cancer or blood disorders can also cause persistent fever.

Identifying the cause of fever helps in determining the right course of treatment, whether through medication, rest, or other remedies.

Types of Fever

Fever can be classified based on its pattern, duration, and cause. Some of the most common types of fever include:

• Intermittent Fever – Temperature rises and falls at regular intervals, commonly seen in malaria.
• Remittent Fever – The temperature fluctuates but never returns to normal, often found in viral infections.
• Continuous Fever – The body temperature remains elevated with little variation, seen in typhoid fever.
• Relapsing Fever – Fever that disappears and returns after a few days, usually due to bacterial infections.
• Low-Grade Fever – Mild fever (99°F - 100.4°F) that lasts for a long time, often linked to chronic illnesses.

Understanding the different types of fever helps doctors diagnose the underlying cause and recommend the appropriate treatment.

Signs and Symptoms of Fever

Apart from an elevated body temperature, fever is often accompanied by various other symptoms. Common signs and symptoms of fever include:

• Chills and shivering – The body feels cold even when the temperature is high.
• Fatigue and weakness – Feeling extremely tired or drained.
• Sweating – As the fever breaks, excessive sweating helps lower the body temperature.
• Headache and body aches – A common response to fever-related infections.
• Loss of appetite – Reduced interest in eating due to illness.
• Dehydration – Fever causes increased fluid loss, leading to dryness and thirst.

Severe fevers (above 103°F) may also cause confusion, seizures, or difficulty breathing, requiring immediate medical attention.

Types of Fever: Symptoms, Causes, and Treatment

Fever is a common symptom of various infections and medical conditions. It occurs when the body's temperature rises above the normal range, usually 98.6°F (37°C). Different types of fever vary in pattern, duration, and underlying cause. Below is a detailed explanation of various fevers, their symptoms, causes, and treatment.

Intermittent Fever

What is Intermittent Fever?
Intermittent fever is a type of fever where the body temperature rises and falls at regular intervals, sometimes returning to normal within a 24-hour cycle.

Symptoms

• Periodic fever spikes followed by normal temperature
• Sweating when the fever subsides
• Weakness and fatigue

Common Causes

• Malaria
• Tuberculosis
• Sepsis

Treatment

• Antibiotics or antimalarial drugs (depending on the cause)
• Hydration and rest

Remittent Fever

What is Remittent Fever?
In this fever, the body temperature fluctuates throughout the day but never returns to normal.

Symptoms

• Continuous fever with variations in intensity
• Sweating and chills
• Weakness

Common Causes

• Bacterial infections (such as endocarditis)
• Viral infections (such as influenza, dengue)

Treatment

• Antibiotics for bacterial infections
• Fluids and fever-reducing medications

Continuous Fever

What is Continuous Fever?

Also called sustained fever, the body temperature remains consistently high without significant fluctuation.

Symptoms

• Persistent fever above 100°F (37.8°C)
• Weakness and fatigue
• Body aches

Common Causes

• Typhoid fever
• Pneumonia
• Urinary tract infections (UTIs)

Treatment

• Antibiotics (if bacterial cause is identified)
• Hydration and fever management

Hyperpyrexia

What is Hyperpyrexia?

Hyperpyrexia is a dangerously high fever above 104°F (40°C), requiring urgent medical attention.

Symptoms

• Severe dehydration
• Confusion or seizures
• Difficulty breathing

Common Causes

• Heatstroke
• Severe infections (sepsis, meningitis)

Treatment

• Immediate cooling measures (ice packs, cold water immersion)
• Hospitalization for IV fluids and medications

Low-Grade Fever

What is Low-Grade Fever?

A mild fever between 99°F - 100.4°F (37.2°C - 38°C) that lasts for a prolonged period.

Symptoms

• Slight body discomfort
• Fatigue
• Mild chills

Common Causes

• Chronic infections (tuberculosis, HIV, hepatitis B/C)
• Autoimmune diseases (lupus, rheumatoid arthritis)

Treatment

• Monitoring and treating the underlying condition
• Plenty of rest and fluids

Relapsing Fever

What is Relapsing Fever?

Fever that disappears and reappears after a few days.

Symptoms

• High fever followed by periods of no fever
• Chills and sweating
• Joint and muscle pain

Common Causes
Bacterial infections like Borrelia (tick-borne relapsing fever)

Treatment

• Antibiotics (doxycycline, penicillin)
• Symptom management with hydration and rest

Septic Fever

What is Septic Fever?
A severe fever caused by sepsis, a life-threatening response to infection.

Symptoms

• High fever above 102°F (38.9°C)
• Rapid heartbeat and breathing
• Confusion and low blood pressure

Common Causes

Bacterial infections spreading into the bloodstream

Treatment

• Emergency medical treatment with IV antibiotics
• Hospitalization and supportive care

Drug-Induced Fever

What is Drug-Induced Fever?
A fever caused by a reaction to medications.

Symptoms

• Fever that starts after taking certain drugs
• Rash or allergic reactions
• No signs of infection

Common Causes

• Antibiotics (penicillin, cephalosporins)
• Antidepressants and chemotherapy drugs

Treatment

• Discontinuation of the suspected drug
• Supportive care with hydration

Rheumatic Fever

What is Rheumatic Fever?
A complication of untreated strep throat that affects the heart and joints.

Symptoms

• Fever and joint pain
• Swollen and red joints
• Heart inflammation (in severe cases)

Common Causes
Untreated strep throat infection

Treatment

• Antibiotics (penicillin)
• Anti-inflammatory medications

Typhoid Fever

What is Typhoid Fever?

A bacterial infection caused by Salmonella typhi, spread through contaminated food and water.

Symptoms

•  Persistent high fever
• Abdominal pain and diarrhea
• Weakness and loss of appetite

Common Causes
Consuming contaminated food or water

Treatment

• Antibiotics (ciprofloxacin, azithromycin)
• Plenty of fluids and rest

Hectic Fever

What is Hectic Fever?
A fever that shows wide temperature fluctuations (above 1.4°C or 2.5°F) within a day. It is often seen in severe infections.

Symptoms

• Rapid and extreme fever spikes
• Profuse sweating when fever drops
• Weakness and weight loss

Common Causes

• Tuberculosis
• Sepsis
• Abscesses or pus-forming infections

Treatment

• Antibiotics or antifungals based on the cause
• Supportive therapy like hydration and fever management

Undulant Fever (Brucellosis)

What is Undulant Fever?
A fever that rises and falls gradually over weeks or months and is linked to bacterial infections like Brucellosis (transmitted from animals to humans).

Symptoms

• Irregular fever pattern
• Sweating and joint pain
• Fatigue and muscle weakness

Common Causes
Brucella bacteria (found in unpasteurized dairy products)

Treatment

• Long-term antibiotic therapy (Doxycycline & Rifampin)
• Avoiding consumption of raw dairy products

Dengue Fever

What is Dengue Fever?
A viral fever caused by the Dengue virus, transmitted through mosquito bites (Aedes aegypti).

Symptoms

• High fever (up to 104°F)
• Severe body pain ("breakbone fever")
• Skin rash and mild bleeding (gum/nose)

Common Causes
Mosquito-borne virus (Dengue virus)

Treatment

• Hydration and pain relievers (Paracetamol)
• Monitoring for complications like Dengue Hemorrhagic Fever (DHF)

Yellow Fever

What is Yellow Fever?
A viral infection transmitted by mosquitoes, primarily in tropical regions.

 Symptoms

• High fever with chills
• Jaundice (yellowing of skin and eyes)
• Organ failure in severe cases

Common Causes
Yellow Fever virus (spread by mosquito bites)

Treatment

• No specific cure; supportive care is given
• Preventive vaccination is available

Pel-Ebstein Fever

What is Pel-Ebstein Fever?
A fever associated with Hodgkin’s lymphoma, where temperature alternates between high and normal every few days.

Symptoms

• Recurring fever for 1-2 weeks
• Night sweats and weight loss
• Swollen lymph nodes

Common Causes
Hodgkin’s lymphoma (blood cancer affecting lymph nodes)

Treatment
Chemotherapy and radiation therapy

Neutropenic Fever

What is Neutropenic Fever?
A fever occurring in people with low white blood cell (WBC) counts, often in cancer patients undergoing chemotherapy.

Symptoms

• Fever above 100.4°F (38°C)
• No specific infection symptoms
• Increased risk of bacterial infections

Common Causes

• Cancer treatment (chemotherapy-induced immunosuppression)
• Bone marrow diseases

Treatment
Antibiotics and immune-boosting therapy

Viral Hemorrhagic Fever (VHF)

What is Viral Hemorrhagic Fever?
A severe and life-threatening fever caused by viruses that affect the blood vessels and lead to internal bleeding.

Symptoms

• High fever with bleeding (nose, gums, or skin)
• Organ failure in severe cases
• Shock and death in advanced stages

Common Causes

• Ebola virus
• Lassa fever virus
• Hantavirus

Treatment

• Isolation and supportive care
• No specific antiviral treatment (except for Lassa fever)

Cat Scratch Fever

What is Cat Scratch Fever?
A bacterial infection caused by Bartonella henselae, transmitted through cat scratches or bites.

Symptoms

• Low-grade fever
• Swollen lymph nodes near the scratch site
• Fatigue and mild infection symptoms

Common Causes
Scratches or bites from infected cats

Treatment

• Mild cases resolve on their own
• Severe cases require antibiotics

Paratyphoid Fever

What is Paratyphoid Fever?
A bacterial infection similar to Typhoid fever, but caused by Salmonella Paratyphi bacteria.

Symptoms

• Prolonged fever with weakness
• Digestive issues (diarrhea or constipation)
• Rose-colored skin rash

Common Causes
Contaminated food and water

Treatment

• Antibiotics (Azithromycin, Ciprofloxacin)
• Hydration and bed rest

PUO (Pyrexia of Unknown Origin)

What is PUO?
A fever lasting for more than three weeks without an identifiable cause.

Symptoms

• Prolonged fever with no clear infection
• Weakness and body aches
• Night sweats

Common Causes

• Tuberculosis
• Autoimmune diseases
• Undiagnosed infections

Treatment

• Extensive diagnostic tests (blood tests, imaging, cultures)
• Treating the underlying condition once identified

Final Thoughts

Fever is a common medical symptom that can indicate anything from a mild viral infection to a serious underlying disease. Recognizing the type of fever and its symptoms helps in early diagnosis and effective treatment. If a fever persists for more than 3-4 days or is accompanied by severe symptoms, consult a doctor immediately.