Sources- tillyoops on TT PMID 37532756 Distinguishing between respiratory viruses is notoriously difficult because they all trigger the same fundamental immune response, leading to a significant overlap of symptoms like coughing, congestion, and sore throats. Because your body uses the same inflammatory "blueprint" to fight off most invaders, a common cold, the flu, and COVID-19 can appear nearly identical during the first few days of infection. This clinical ambiguity is why healthcare providers often rely on diagnostic testing rather than physical observation alone to confirm which pathogen is responsible for an illness. Despite these similarities, specific "signature" symptoms can provide clues to the virus's identity. The flu is most frequently associated with a sudden, high fever and intense headaches that hit with startling speed, often leaving the patient feeling physically crushed by muscle aches. In contrast, COVID-19 is more likely to cause profound, lingering fatigue and a persistent dry cough that may be accompanied by shortness of breath. While a cold usually stays "above the neck" with sneezing and a runny nose, the systemic exhaustion of COVID-19 and the sharp, febrile intensity of the flu remain their most telling clinical markers. #cold #cough #flu