Frequently asked questions about flu

Flu is a very contagious illness. One person with influenza can infect others the day before they notice any symptoms until 5–7 days after they appear. Young children and people with a compromised immune system can transmit the virus for longer periods.

Especially for people at a high risk of infection (children under 5, pregnant women, older adults and people with chronic illnesses), the flu can be more severe and complications can develop, resulting in hospitalisation in certain cases.

In general, healthy people with flu can manage the illness themselves without needing a confirmed diagnosis or determination of the type of virus responsible. This is because diagnostic test results do not alter the treatment, which normally consists of hydration, rest and fever control.

If hospitalisation is required, a quick test is requested to detect the virus – influenza, COVID-19 or RSV – as well as a blood test to evaluate the status and severity of the infection. In some suspected cases of complications, such as pneumonia, the doctor may request a confirmatory chest X-ray. Blood oxygen is also measured to determine if oxygen needs to be administered.

Hospitalisation is recommended when a person with flu has potential life-threatening complications. This is the safest place to monitor heart rate, respiratory rate and temperature and to ensure that the response to treatment is adequate.

Under certain circumstances, isolation may be recommended to protect both patient and other hospital patients who may be at risk of infection. This is because influenza is very contagious, especially in the first few days after the onset of symptoms.

If the flu infection is not too severe and with few complications, you may be discharged after 3–4 days. However, there are many factors that influence hospital stay, such as the patient's immune status, chronic diseases or complications developed due to influenza.

Antivirals are medications used to eliminate flu viruses and help control the infection. If they are administered in the first few days after the appearance of symptoms, they can reduce the length of the flu process. Antivirals have to be prescribed by a healthcare professional, as they can have side effects.

Remember: antibiotics are ineffective against viruses; and the flu is caused by a virus.

Rest is highly recommended, but you should still try to follow your normal routine and exercise a little, if possible; provided your healthcare professional does not tell you otherwise. It is best to find a balance between rest and activity periods during the day, at your own pace. Try to get out of bed and be active but without tiring yourself out.

Your healthcare professional will probably prescribe some medicines for you to take, although this depends on each specific case. It is very important to follow the doctor’s indications and attend scheduled visits.