The flu has hit hard and spread fast this year. Every state except Hawaii is reporting widespread influenza activity. Hospitalizations are also higher than they’ve been in several years, and more than 700 flu deaths have been recorded so far this season, up from around 300 at this time last year.

Health experts say there’s no need to panic, but it is important to know what to do if you get sick—and when it makes sense to get treatment from your doctor or head to the ER. 

More on Dealing With Colds & the Flu

This year, the predominant flu strain that's circulating is the H3N2. According to the Centers for Disease Control and Prevention, this strain is associated with more infections, hospitalizations, and deaths than other ones. Plus, the flu vaccine tends to be less effective at preventing infection from H3N2 than it is with other strains. (Nevertheless, it’s still vitally important to get the vaccine, because it can lessen the risk of complications and hospitalization if you do get the flu.)

Here’s how to know when you need to see the doctor or get emergency flu treatment.

Get the Right Flu Care at the Right Time

For most people, the flu runs its course after one to two weeks. But those more likely to experience potentially dangerous complications from flu include: children under 5; adults age 65 or older; pregnant women; people with chronic conditions such as heart, lung, kidney, or liver disease, or diabetes; those who have HIV or who are taking immunosuppressant drugs such as prednisone (Deltasone, Prednicot, others and generic) or drugs used in cancer chemotherapy.

Serious complications that people can experience include pneumonia and sepsis (a sometimes deadly reaction the body can have to infection). To stay safe:

Take these steps at home. “With flu it’s typical to have chills, high fever, muscle aches, and feel very poorly,” says Andrew Pavia, M.D., professor of pediatrics and medicine at the University of Utah and a spokesman for Infectious Diseases Society of America.

Most people who have the flu should stay home to avoid infecting others. Get plenty of rest and fluids in sweet or salty form—tea, juice, and broth-based soups are good options. To bring down fever and calm aches and pains, acetaminophen (Tylenol and generic), ibuprofen (Advil and generic), or naproxen (Aleve and generic) can help.

Know when to call the doctor. For those at increased risk of complications—young children, older adults, pregnant women, and those with one of the chronic conditions noted above—contact your doctor’s office if you suspect you have the flu so that you can get clear instructions for care. 

For everyone else, experts says that most people with the flu get better on their own and don't need medical attention. It doesn't hurt to call your doctor, however, if you're concerned about your illness or your symptoms seem severe.

When it comes to medications for the flu, if you're really miserable, prescription antiviral drugs such as oseltamivir (Tamiflu and generic) or zanamivir (Relenza) may shorten the illness by a day or so—which may be of modest benefit to an otherwise healthy person, Pavia says. It may be more important for people in the high-risk groups listed above to start antiviral medication right away, because these drugs may reduce the risk of complications and hospitalizations from flu. Antiviral treatment needs to be started within 48 hours of first symptoms to be effective.

If you call a doctor who knows you well, you may not even need to have an office visit. “It is very reasonable to get a prescription over the phone if the likelihood of the flu is very high,” Pavia says.

Get to the ER. Whether you're in a high-risk category or not, key warning signs that you should go to the ER are fever that climbs to 103° F or higher, or trouble breathing while at rest or with slight exertion, says Marvin M. Lipman, M.D., Consumer Reports’ chief medical adviser.

In addition, the CDC advises that adults visit the emergency room if they experience pain or pressure in the chest or abdomen, sudden dizziness, confusion, or severe vomiting. These could all be signs of dangerous complications from flu. But unless you're very sick, it's best to avoid the emergency room—it's easy to pick up other infections there.

Take children to the emergency room if they are breathing fast or have difficulty breathing, bluish skin, fever with a rash, are drinking very little, or are unresponsive.

The CDC also recommends that anyone whose flu symptoms ease but then return—especially with fever and cough—should also go to the ER. This can be a sign that a secondary infection—such as pneumonia—is taking hold.

And if you’re unsure of the best course of action? “When in doubt, call your doctor,” Lipman advises.