The flu, also called influenza, is a respiratory infection caused by viruses. Each year, millions of Americans get sick with the flu. Sometimes it causes mild illness. But it can also be serious or even deadly, especially for people over 65, newborn babies, and people with certain chronic illnesses.

The flu is caused by flu viruses that spread from person to person. When someone with the flu coughs, sneezes, or talks, they spray tiny droplets. These droplets can land in the mouths or noses of people who are nearby. Less often, a person may get flu by touching a surface or object that has flu virus on it and then touching their own mouth, nose, or possibly their eyes.

Symptoms of the flu come on suddenly and may include:

• Fever or feeling feverish/chills
• Cough
• Sore throat
• Runny or stuffy nose
• Muscle or body aches
• Headaches
• Fatigue (tiredness)

Some people may also have vomiting and diarrhea. This is more common in children.

Sometimes people have trouble figuring out whether they have a cold or the flu. There are differences between them:

Sometimes people say that they have a "flu" when they really have something else. For example, "stomach flu" isn't the flu; it's gastroenteritis.

Some people who get the flu will develop complications. Some of these complications can be serious or even life-threatening. They include:

• Bronchitis
• Ear infection
• Sinus infection
• Pneumonia
• Inflammation of the heart (myocarditis), brain (encephalitis), or muscle tissues (myositis, rhabdomyolysis)

The flu also can make chronic health problems worse. For example, people with asthma may have asthma attacks while they have flu.

Certain people are more likely to have complications from the flu, including:

• Adults 65 and older
• Pregnant women
• Children younger than 5
• People with certain chronic health conditions, such as asthma, diabetes, and heart disease

To diagnose the flu, health care providers will first do a medical history and ask about your symptoms. There are several tests for the flu. For the tests, your provider will swipe the inside of your nose or the back of your throat with a swab. Then the swab will be tested for the flu virus.

Some tests are quick and give results in 15-20 minutes. But these tests are not as accurate as other flu tests. These other tests can give you the results in one hour or several hours.

Most people with the flu recover on their own without medical care. People with mild cases of the flu should stay home and avoid contact with others, except to get medical care.

But if you have symptoms of flu and are in a high risk group or are very sick or worried about your illness, contact your health care provider. You might need antiviral medicines to treat your flu. Antiviral medicines can make the illness milder and shorten the time you are sick. They also can prevent serious flu complications. They usually work best when you start taking them within 2 days of getting sick.

The best way to prevent the flu is to get a flu vaccine every year. But it's also important to have good health habits like covering your cough and washing your hands often. This can help stop the spread of germs and prevent the flu.

Centers for Disease Control and Prevention

The flu (influenza) is a respiratory infection. It is caused by influenza viruses that infect your nose, throat, and lungs. These viruses can spread from person to person.

Most people with the flu get better on their own, without medical care. But for some people, the flu is serious. It can cause complications and sometimes even death. People who are 65 and older, under age 5, pregnant, or have certain health conditions are at higher risk of flu complications.

Getting vaccinated against the flu each year is best way to lower your risk of the flu and its complications.

There are many reasons to get a flu shot each year:

• It may keep you from getting sick with the flu.
• If you do get the flu, it may be less severe. You may also be less likely to have complications or need to be hospitalized with the flu.
• If you have certain chronic health conditions, getting a flu shot may help prevent the flu from making your condition worse. For example, if you have COPD or diabetes, the flu can worsen your condition so much that you might need to be hospitalized. Getting a flu shot can lower this risk.
• Getting the vaccine during pregnancy not only helps protect you from the flu during and after pregnancy. It also helps protect your baby from flu during their first few months of life.
• It has been shown to lower the risk of severe life-threatening flu in children.
• It may also protect the people around you, including those who are at higher risk of complications.

The flu vaccine causes your immune system to make antibodies about two weeks after you get the shot. These antibodies provide protection against infection with the flu viruses that are in the vaccine.

The U.S Centers for Disease Control and Prevention (CDC) recommends annual flu shots for everyone 6 months and older, with a few rare exceptions.

Flu shots are especially important for people who are at high risk of developing serious complications from the flu.

There are different types of flu vaccines. There are injectable vaccines (shots) and nasal spray vaccines. There are also some vaccines especially for people 65 and older. Ask your health care provider which one is right for you.

There are some people who should not get a flu shot:

• Children younger than 6 months of age.
• Have severe, life-threatening allergies to flu vaccine or any ingredient in the vaccine. This might include gelatin, antibiotics, or other ingredients.

Some people need to talk to their provider before they get a flu shot. They include people who:

• Have an allergy to any of the ingredients in the vaccine.
• Have ever had Guillain-Barre syndrome (GBS). Some people with a history of GBS should not get a flu vaccine.

If you are moderately or severely ill, you usually need to wait until you recover before getting a flu shot.

You need to get a flu shot every year because:

• Your immune protection from the vaccine declines over time. You need to get the shot every year to boost that protection.
• Flu viruses are constantly changing, so every year, the flu vaccine is updated. The flu vaccine will include protection against the viruses that will most likely be common during the upcoming flu season.

For most people who need only one dose of the flu vaccine for the season, September and October are usually good times to get it. It's best to be vaccinated by the end of October.

Some children need two doses of the flu vaccine. They should get their first dose as soon as the vaccine is available. They need to get the second dose at least four weeks after the first.

If you are pregnant, talk to your provider about when to get the vaccine. When you should get it can vary, based on how far along you are in your pregnancy.

Flu vaccines have been shown to be safe. But like any medical product, they can cause side effects. If you have any side effects, they are usually mild and go away on their own within a few days. Common side effects include:

• Soreness, redness, and/or swelling from the shot
• Headache
• Fever
• Nausea
• Muscle aches

The flu shot, like other injections, can occasionally cause fainting. In rare cases, some people have a serious allergic reaction.

Centers for Disease Control and Prevention

Safe steps in food handling, cooking, and storage can prevent foodborne illness. There are four basic steps to food safety at home:

• Clean - always wash your fruits and vegetables, hands, counters, and cooking utensils.
• Separate - keep raw foods to themselves. Germs can spread from one food to another.
• Cook - foods need to get hot and stay hot. Heat kills germs.
• Chill - put fresh food in the refrigerator right away.

In the grocery store, avoid cans that are bulging or jars that have cracks or loose lids. Check packages to be sure food hasn't reached its expiration date.

United States Department of Agriculture

Your gallbladder is a pear-shaped organ under your liver. It stores bile, a fluid made by your liver to digest fat. As your stomach and intestines digest food, your gallbladder releases bile through a tube called the common bile duct. The duct connects your gallbladder and liver to your small intestine.

Your gallbladder is most likely to give you trouble if something blocks the flow of bile through the bile ducts. That is usually a gallstone. Gallstones form when substances in bile harden. Rarely, you can also get cancer in your gallbladder.

Many gallbladder problems get better with removal of the gallbladder. Fortunately, you can live without a gallbladder. Bile has other ways of reaching your small intestine.

Your digestive or gastrointestinal (GI) tract includes the esophagus, stomach, small intestine, large intestine or colon, rectum, and anus. Bleeding can come from any of these areas. The amount of bleeding can be so small that only a lab test can find it.

Signs of bleeding in the digestive tract depend on where it is and how much bleeding there is.

Signs of bleeding in the upper digestive tract include:

• Bright red blood in vomit
• Vomit that looks like coffee grounds
• Black or tarry stool
• Dark blood mixed with stool

Signs of bleeding in the lower digestive tract include:

• Black or tarry stool
• Dark blood mixed with stool
• Stool mixed or coated with bright red blood

GI bleeding is not a disease, but a symptom of a disease. There are many possible causes of GI bleeding, including hemorrhoids, peptic ulcers, tears or inflammation in the esophagus, diverticulosis and diverticulitis, ulcerative colitis and Crohn's disease, colonic polyps, or cancer in the colon, stomach or esophagus.

The test used most often to look for the cause of GI bleeding is called endoscopy. It uses a flexible instrument inserted through the mouth or rectum to view the inside of the GI tract. A type of endoscopy called colonoscopy looks at the large intestine.

NIH: National Institute of Diabetes and Digestive and Kidney Diseases