Flu-like illness or influenza like illness is a category of illnesses that involve viruses with similar symptoms or patients who have the flu, but the test may not show positive result to flu. In short, Flu-like illness can be the diagnosis when doctors are not sure what virus is at play since signs and symptoms of bad colds and several other respiratory viruses which can be difficult to distinguish from the flu.
Many viruses can cause a flu-like illness. A few causes of Flu-like illness are –
- The common illness that can cause flu like illness are gastroenteritis, rhinoviral disease, influenza, and sometimes life-threatening diseases such as meningitis, sepsis, and leukemia.
- Infectious diseases causing Flu like illness include malaria, acute HIV/AIDS infection, herpes, hepatitis C, Lyme disease, rabies, myocarditis, dengue fever, pneumonia, measles, etc.
- Pharmaceutical drugs that may cause Flue-like illness include many biologics such as interferons and monoclonal antibodies. Chemotherapeutic agents also commonly cause flu-like symptoms.
Flu-like illnesses typically cause a high temperature, aches and pains in muscles and joints, a cough and various other symptoms.
Symptoms commonly include fever, shivering, chills, dry cough, loss of appetite, body aches, nausea, headache, fatigue, etc. In most cases, the symptoms are caused by cytokines released by immune system activation, and are thus relatively non-specific.
When you are diagnosed with influenza, your doctor may be able to prescribe antiviral medications to help shorten the duration and reduce the severity of your symptoms. Unfortunately, these antiviral medications are ineffective against flu-like illnesses that are not caused by the influenza virus.
Instead, treating a flu-like illness will most likely be similar to treating other viral infections. You can treat the symptoms with over-the-counter medications and wait for the virus to run its course.