What Causes High Fever?

A high fever, defined as a body temperature of 100.4°F (38°C) or higher, can be caused by a wide range of underlying conditions, including infections, inflammatory processes, and other medical issues. Here are some common causes of high fever:

  • Infections: Infections are one of the most common causes of high fever. Bacterial, viral, fungal, and parasitic infections can all lead to elevated body temperatures. Examples include:
    • Viral infections like influenza (the flu) and COVID-19.
    • Bacterial infections like strep throat or urinary tract infections.
    • Fungal infections like candidiasis or aspergillosis.
    • Parasitic infections like malaria.
  • Inflammatory Conditions: Certain inflammatory conditions can trigger a fever response. Conditions such as rheumatoid arthritis, systemic lupus erythematosus (SLE), and inflammatory bowel disease (IBD) may be associated with high fever.
  • Heat-Related Conditions: Excessive exposure to heat, especially in hot weather or due to heatstroke, can cause a high fever. Dehydration can exacerbate this condition.
  • Medications: Some medications can cause a fever as a side effect or as an allergic reaction. If you suspect that a medication is causing your fever, consult your healthcare provider.
  • Autoimmune Disorders: Autoimmune diseases like systemic vasculitis or giant cell arteritis can cause fevers as part of their symptom profile.
  • Cancers: Some types of cancer, particularly lymphomas and leukemias, can lead to persistent high fevers.
  • Neurological Conditions: Certain neurological conditions, such as central nervous system infections or disorders, may cause a high fever.
  • Metabolic Disorders: Certain metabolic disorders, such as hyperthyroidism, can lead to an elevated body temperature.
  • Travel-Related Illnesses: Travel to regions with specific diseases, such as dengue fever or typhoid, can result in high fever if an individual becomes infected.
  • Immune Reactions: In rare cases, severe immune reactions to various triggers, such as medications or certain infections, can cause high fever. This is known as Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) or other similar syndromes.

It’s important to note that a fever is often the body’s natural response to an infection or other underlying issue. In many cases, fever helps the immune system fight off the infection. However, a persistent or very high fever, especially in infants, young children, or individuals with certain underlying medical conditions, should be evaluated by a healthcare provider. Treatment for a fever often involves addressing the underlying cause, managing symptoms, and, in some cases, using antipyretic medications like acetaminophen or ibuprofen to lower the fever and provide relief. Always consult a healthcare professional for a proper diagnosis and guidance on managing a high fever.