Synonyms
Influenza, real flu, virus fluThe flu can lead to complications or even death, especially for people with a weaker immune system, such as the chronically ill, the elderly, small children and pregnant women. Often a so-called super infection with bacteria and a resulting pneumonia (= pneumonia). One speaks of a superinfection when an already existing infection, in this case with influenza viruses, is followed by an additional infection with bacteria.
In most cases, this secondary pneumonia (the primary disease is influenza, which in this case is not responsible for the pneumonia) is caused by bacteria such as pneumococcus, Staphylococcus aureus or Haemophilus influenzae and only occurs after 3 – 4 days. Symptoms are a renewed rise in fever, coughing with strong purulent secretion formation and shortness of breath. The physician can recognize typical signs of pneumonia by listening to the lungs.
Less common than bacterial pneumonia, but even more dangerous is primary influenza pneumonia, which is caused by the influenza viruses themselves. People with heart disease are particularly at risk for this type of pneumonia. Influenza pneumonia is an interstitial pneumonia, i.e. the supporting tissue of the lung is highly inflamed.
Symptoms are permanently high fever, increasing cough and shortness of breath until the lips and/or face turn blue. Little secretion is coughed up and the doctor usually cannot detect anything abnormal when listening to the lungs. Mixed pneumonia caused by influenza viruses and bacteria is also possible.
The symptoms then resemble both diseases. A pneumonia is in itself a threatening disease, but if the body is already weakened by the flu, it is even more dangerous and must be treated and monitored in hospital. You can find more information on how to detect pneumonia on our website: How do I detect pneumonia?
Peri- or myocarditis can also occur – an inflammation of the pericardium or heart muscle. These diseases often lead to cardiac arrhythmia and can thus cause sudden cardiac death. Due to the weakening of the body by the flu, existing heart diseases can be aggravated and also lead to death.
A muscle inflammation, the so-called myositis can also be caused by the influenza viruses. This is a severe inflammation of the muscles, especially the legs. The pain goes beyond the normal pain in the limbs, there is swelling and excessive pressure sensitivity of the affected muscles.
The central nervous system (CNS), i.e. the brain and spinal cord, can also be affected. Inflammation of the membranes surrounding the brain and spinal cord (meninges) caused directly by the flu viruses can occur (meningitis) or purulent meningitis due to a superinfection with bacteria. The brain itself can also be infected (encephalitis), the spinal cord (myelitis) up to a paraplegia with paralysis.
An inflammation of the organ of balance in the inner ear (labyrinthitis) can also be a complication of influenza. A very rare complication is Reye’s syndrome, which can occur in children and adolescents up to about 18 years of age who are infected with influenza and treated with acetylsalicylic acid (contained in Aspirin or ASS 100, among others). This leads to nausea, vomiting and cramps, and those affected often fall into a coma and die of liver failure and irreversible brain damage. ASA should only be administered to children and adolescents in explicit consultation with a doctor, as Reye’s syndrome can also occur in the case of numerous other viral infections (e.g. chicken pox).
