Different Types of Flu

Influenza A and influenza B are the types most often associated with seasonal human illness. Influenza A has subtypes identified by surface proteins, whereas influenza B is described by lineages. A test may identify influenza, but symptoms alone usually cannot show which type is present.

Flu can begin suddenly with fever or chills, tiredness, headache, muscle aches, cough and sore throat. Some people also have nausea, vomiting or diarrhoea. A cold, COVID-19 and other infections can look similar, so a clinician may consider timing, exposure, examination and testing together.

Rest, drink fluids regularly, and use fever or pain medicine only as directed for you. Stay away from close contact while unwell and improve ventilation around others. Antiviral treatment may be considered for some people, particularly when started early or when illness is more serious; it requires a clinician’s advice.

Do not take antibiotics for influenza unless a clinician identifies a bacterial infection. If joint aches or swelling are prominent, mention them during an assessment rather than assuming they are a separate orthopaedic problem.

Seek urgent care for trouble breathing, chest pain, confusion, fainting, severe dehydration, blue lips, or a marked deterioration after initial improvement. Contact a clinician sooner if you are pregnant, have a long-term medical condition, have a weakened immune system, or are caring for a very young child or older adult.

Ask whether testing is useful, whether an antiviral is appropriate, how to manage fever safely, when you can return to normal activities, and which warning signs matter for your health history. Tell the clinician about current medicines and any persistent joint swelling.