Differential Diagnosis for Nausea followed by Sore Throat, Dry Cough, and Fatigue

Single Most Likely Diagnosis

• Viral Pharyngitis: This is the most likely diagnosis given the combination of nausea, sore throat, and dry cough. Viral pharyngitis is a common condition caused by viruses such as rhinovirus, coronavirus, or adenovirus, and its symptoms match the presentation described.

Other Likely Diagnoses

• Influenza: Influenza (the flu) can present with sudden onset of nausea, sore throat, dry cough, and significant fatigue. The symptoms can be severe and are often accompanied by fever and body aches.
• COVID-19: Given the current pandemic, COVID-19 should be considered, especially if the patient has been exposed to someone with the virus. Symptoms can include nausea, sore throat, dry cough, and fatigue, among others.
• Mononucleosis (Mono): Caused by the Epstein-Barr virus, mono can present with sore throat, fatigue, and sometimes nausea. However, it typically includes lymphadenopathy and fever.

Do Not Miss Diagnoses

• Strep Throat: Although less likely given the absence of specific symptoms like fever and swollen lymph nodes, strep throat (caused by Group A beta-hemolytic streptococci) is a critical diagnosis not to miss due to its potential for complications like rheumatic fever if left untreated.
• Pertussis (Whooping Cough): Especially in adults or individuals not up to date on their vaccinations, pertussis can present with a dry cough and may be preceded by nonspecific symptoms like nausea and sore throat.
• Pneumonia: While pneumonia typically presents with more severe respiratory symptoms, it can start with mild symptoms like dry cough and fatigue. It's crucial not to miss this diagnosis due to its potential severity.

Rare Diagnoses

• Lemierre's Syndrome: A rare condition characterized by a sore throat followed by neck pain and fever, due to a bacterial infection (usually Fusobacterium necrophorum) that can lead to sepsis and other complications.
• Tuberculosis (TB): Although rare in many parts of the world, TB can present with chronic cough, fatigue, and sometimes sore throat. It's more likely in individuals with risk factors such as immunocompromised states or recent travel to endemic areas.
• Cytomegalovirus (CMV) Infection: CMV can cause a mononucleosis-like syndrome with sore throat, fatigue, and sometimes nausea, particularly in immunocompromised individuals or those with significant exposure risks.