COVID-19 is a respiratory illness presenting with a wide range of signs and symptoms. One of the most frequently reported indicators of infection is an elevated body temperature. Monitoring temperature at home is a simple step to assess health status during illness. Knowing the specific threshold that defines a fever and understanding how to accurately measure it are important for making informed decisions about self-care and when to contact a healthcare provider.
Understanding the Fever Threshold
A fever represents a temporary increase in the body’s temperature set point, often triggered as part of the immune system’s response to an infection. The standard temperature recognized as a fever in adults is \(100.4^{\circ}\text{F}\) or \(38^{\circ}\text{C}\). This value is widely used by medical professionals to define when an elevated temperature warrants concern.
The generally accepted normal body temperature is approximately \(98.6^{\circ}\text{F}\) (\(37^{\circ}\text{C}\)), but this is merely an average. An individual’s baseline temperature can naturally fluctuate throughout the day, often being lower in the morning and slightly higher in the late afternoon. A temperature between \(99.5^{\circ}\text{F}\) and \(100.3^{\circ}\text{F}\) is often referred to as a low-grade fever and may not require immediate treatment.
The \(100.4^{\circ}\text{F}\) mark defines a true fever, regardless of the cause. Fever is a common symptom of COVID-19, though not everyone who contracts the virus will experience an elevated temperature. When present, the fever is the body’s attempt to create an inhospitable environment for the invading virus, slowing its replication.
Methods for Measuring Body Temperature
Accurately measuring body temperature requires using a reliable digital thermometer and following the correct technique for the chosen site. Different measurement locations provide slightly different readings because they are closer or farther away from the body’s core temperature. For practical home use, the most common methods are oral, temporal artery (forehead), and axillary (armpit).
Oral temperature measurement is generally considered one of the more accurate non-invasive methods. To ensure an accurate reading, the thermometer tip must be placed deep under the tongue, and the mouth kept closed until the device signals completion. Wait 30 minutes after eating, drinking, or exercising before taking an oral temperature, as these activities can significantly alter the reading.
Temporal artery thermometers use an infrared scanner to measure heat from the artery across the forehead. This method is convenient and rapid, but readings are typically \(0.5^{\circ}\text{F}\) to \(1^{\circ}\text{F}\) lower than oral temperature, and accuracy can be influenced by sweat or drafts. The axillary (armpit) method is the least reliable, measuring skin surface temperature and usually reading \(0.5^{\circ}\text{F}\) to \(1^{\circ}\text{F}\) lower than oral. For axillary measurement, the thermometer must be placed high against the bare skin, and the arm held tightly against the body until the device beeps.
Managing Fever and Knowing When to Call a Doctor
Home Management
For most healthy adults, a fever caused by COVID-19 can be safely managed at home with supportive care. The primary goals of home management are to prevent dehydration and maintain comfort. Staying well-hydrated is important, as fever increases fluid loss through sweating and respiration; clear fluids like water or electrolyte-replacement drinks are recommended.
Medication Use
Rest is also a valuable component of recovery, allowing the body to dedicate energy to fighting the infection. Over-the-counter medications such as acetaminophen (Tylenol) or ibuprofen (Advil, Motrin) can be used to help reduce the fever and relieve body aches. It is important to follow the dosing instructions on the packaging carefully and not exceed the maximum daily dose.
When to Contact a Healthcare Provider
While most fevers resolve on their own, certain symptoms indicate the need for medical attention. Contact a healthcare provider if a fever above \(101^{\circ}\text{F}\) (\(38.3^{\circ}\text{C}\)) persists for more than three days or spikes suddenly. If a temperature reaches \(103^{\circ}\text{F}\) (\(39.4^{\circ}\text{C}\)) or higher in an adult, contact a doctor immediately. For individuals with underlying health conditions or those at higher risk, contact a medical professional even if milder symptoms are worsening.
Emergency Warning Signs
Seeking emergency care is necessary if you experience severe symptoms, including:
- Difficulty breathing
- Persistent pain or pressure in the chest
- New confusion or inability to stay awake
- Bluish or pale discoloration of the lips or face
- Signs of severe dehydration like dizziness or reduced urine output