How do I know if I have flu or just a bad cold?

A bad cold will start gradually, sometimes with sneezing or a sore throat. Symptoms are generally limited to the nose and throat, often also with a cough, which may be mucousy or phlegmy. You may feel tired and 'washed out' with it, but are usually able to keep going.

Flu often starts suddenly, with a high temperature, over 38C, shivering, sweating, muscle aches, exhaustion, and occasionally gut symptoms. You are usually stuck in bed for a few days, off your food, and mostly sleeping.

What is the difference between COVID-19 and flu?

The symptoms of COVID-19 and flu can be similar. It may be recommended to take a COVID-19 test to tell the difference. A feature of COVID-19 which is rarely found in other respiratory illnesses is a loss of, or alteration of, the sense of taste or smell. This is not just due to your nose being blocked but is caused by viral damage to the taste and smell mechanism. Between 50-60% of adults have altered smell or taste with COVID-19 infection.

I had a flu jab - can I still take Tamiflu?

The flu jab (vaccine) is a very effective way to prevent flu, but each year the flu virus changes and mutates. Occasionally a different strain which isn't in that year's vaccine can cause a flu outbreak.

Tamiflu can still be used after flu vaccination to both prevent and to treat flu. However, you should wait at least 10 days after the flu jab or the vaccine may not be effective.

Can Tamiflu be used to treat or prevent COVID-19?

No. In the early days of the COVID-19 pandemic, it was hoped that Tamiflu would be an effective treatment. Unfortunately medical trials showed no benefit.

Which viruses does Tamiflu treat?

Tamiflu is licensed to treat and prevent flu caused by the influenza viruses A and B. These viruses are the ones responsible for seasonal flu which also includes swine flu which is caused by an influenza type A virus.

What is the evidence for Tamiflu working in flu?

The evidence for the efficacy of tamiflu in preventing or treating influenza is mixed.

The original trials showed a big reduction in those developing flu when taking Tamiflu and a reduction in complications like pneumonia. They also showed a reduction of 1-2 days in the length of illness.

More recent studies are less positive and a review of research up to 2014 by the Cochrane Library concluded that Tamiflu only shortens an episode of flu by 16.8 hours. It also raised concern about the frequency and severity of side effects, especially psychiatric conditions such as depression and suicidal thoughts. There was no significant benefit from Tamiflu in patients in high risk situations.

See also Centre for Evidence-based Medicine - Tamiflu as a treatment for influenza.

Why can I only have one course of Tamiflu per flu season?

This reduces the possibility of developing a Tamiflu resistant strain of influenza.

What is the best way to prevent flu?

The best way to prevent flu is to have a flu vaccine early in the flu season. Many people in the UK are eligible for a free NHS flu jab, and many chemists can also provide them for a modest cost.

Tamiflu can be used to prevent flu. Take one capsule once daily for 10 days after contact with a person with flu.

What is the best way to treat flu?

Most healthy people will get over flu without needing special treatments.

  • Stay in bed, rest and sleep.
  • Drink fluids to keep well hydrated.
  • Take paracetamol or ibuprofen to reduce fever (high temperature) and soothe aching muscles.

Tamiflu can be used to treat flu and usually shortens the illness by around half a day. Start within 48 hours of first flu symptoms and take one capsule twice a day for 5 days.

How long will I be infectious for if I have flu?

A healthy adult is likely to pass flu on from a day before they themselves have symptoms until 7 days after their symptoms start. They are most likely to spread it in the first 3-4 days of the illness.

What are the medical complications of flu?

The medical complications of flu can include:

  • Bronchitis.
  • Bacterial pneumonia.
  • Ear infection.
  • Sinus infection.
  • Tonsillitis.
  • Febrile Convulsions (fits related to fever).
  • Worsening of chronic medical conditions like congestive heart failure, asthma, COPD, or diabetes.
  • Rarely meningitis or encephalitis (infection in the brain or brain lining).

Why is flu dangerous in pregnancy?

A woman's immune system naturally weakens in pregnancy. This makes pregnant women more vulnerable to any infection and she is also more likely to develop bronchitis and chest infections with flu. Also the flu can cause premature labour, low birth weight, and very occasionally miscarriage and stillbirth. Pregnant women should have a flu jab.

Can I take Tamiflu if I'm pregnant?

Yes. It is often recommended because of the potential severe impact of flu when pregnant. However it is better to have a flu jab.

If you do get flu whilst pregnant, speak to your GP or midwife. Dr Fox does not prescribe in pregnancy.

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Dr Amanda Wood

Authored 20 October 2021 by Dr A. Wood
MB ChB Manchester University 1984. Former NHS GP in Bristol. GMC no. 2855422

Reviewed by Dr C. Pugh, Dr B. Babor
Last reviewed 04 April 2023
Last updated 19 July 2024