Most people who come down with the flu experience mild illness that usually runs its course within a week or two. In this case, a trip to the doctor might not be necessary.

But for people who are at risk of complications from the disease, the flu can become life-threatening. Even if you live a healthy lifestyle, you can get seriously ill from flu.

The flu can cause some or all of these symptoms:

  • cough
  • sore throat
  • runny or stuffed nose
  • muscle aches
  • headaches
  • tiredness
  • fever
  • vomiting and diarrhea (more common in children than adults)
  • chills

Every year, between 5 to 20 percent of Americans get sick with the flu. The Centers for Disease Control and Prevention (CDC) has estimated between 9.3 million and 49 million cases of the flu every year since 2010.

So, when should you see a doctor if you’ve got the flu? Here are eight reasons to seek medical attention.

1. You have shortness of breath or difficulty breathing

Being sick with flu shouldn’t affect your breathing. It could be a sign of a something more serious, such as pneumonia, an infection of the lungs.

Pneumonia is a common and potentially serious complication of flu. It causes up to 49,000 deaths in the United States every year.

2. You feel pain or pressure in your chest or abdomen

Feeling pain or pressure in your chest is another warning sign that you shouldn’t ignore.

The flu can trigger heart attacks and strokes in people with heart disease. Chest pain is also a common symptom of pneumonia.

3. You’re vomiting often

Vomiting depletes your body of fluids, making it difficult to get well from the flu. Because of this, you should call your doctor to get examined.

Vomiting or not being able to keep liquids down could also be a sign of sepsis, a serious flu-related complication. If not treated immediately, sepsis can lead to organ failure.

4. You’re pregnant

If you’re pregnant and get sick with the flu, you’re at a higher risk of complications, such as bronchitis.

You’re also at a higher risk of having your baby prematurely or at a low birthweight. In some cases, having the flu while pregnant may even lead to stillbirth or death.

The CDC recommends that all pregnant women get a flu shot. But it does not recommend the nasal spray flu vaccine for pregnant women.

5. You have asthma

One in 13 Americans has asthma, a disease that affects the airways in the lungs. Because people with asthma tend to have weaker immune systems, symptoms of the flu are often worse.

Adults and children with asthma are also more likely to be hospitalized for flu complications and develop pneumonia compared with those who don’t have asthma.

If you have asthma, you should see your doctor about taking an antiviral medication. But you shouldn’t take the antiviral drug zanamivir (Relenza), as it can cause wheezing or other lung problems.

6. You have heart disease

About 92 million Americans have some form of heart disease or live with the aftermath of a stroke. If you are one of these people, you’re more likely to develop serious flu-related complications.

Researchers have found that the risk of a heart attack goes up six-fold during the first week of a confirmed flu infection.

If you live with heart disease, the best way to avoid the virus and potential hospital care is to get the flu vaccine.

7. Your symptoms get better, then come back worse

Your symptoms shouldn’t reappear after they’ve subsided. A high fever and a severe cough that produces green or yellow mucus are possible signs of an infection such as pneumonia.

8. You’re among those considered at high risk of complications from flu

You’re at a higher risk of flu complications and should seek medical treatment right away if you fall into one of these categories:

  • children younger than 5, but especially those younger than age 2
  • adults ages 65 years and older
  • nursing home residents
  • people with diabetes, kidney or liver disorders, and chronic lung disease
  • people with weakened immune systems due to HIV or cancer
  • people younger than 19 who are on long-term aspirin therapy
  • people who are obese with a body mass index of 40 or more

You can use over-the-counter medications to ease your symptoms at the start, but it’s more important to see a doctor immediately.

Antiviral drugs can only be prescribed by a doctor or healthcare provider. Taking antiviral medications within two days of getting sick has been shown to lessen symptoms and shorten the length of the illness by one day.

The takeaway

If you relate to any of the points above, you should make seeing your doctor a priority. Even if you don’t have asthma, chest pain, or symptoms that have returned, if you’re ill with the flu virus and you feel something isn’t quite right, you should seek medical attention.