When you see a doctor because you're not feeling well, you might expect a prescription for antibiotics. After all, you feel bad and you want to get better fast.

You're hardly alone: Doctors prescribe millions of antibiotics for infections every year.

But half of the time those drugs aren't needed, according to an expert panel recently convened by the Centers for Disease Control and Prevention. Unless the infection is caused by bacteria—which is usually not the case—the drugs will have no effect.

Doctors know that, of course. But they often prescribe antibiotics anyway, in part because patients expect it—and it's easier and faster than explaining why they aren't necessary.

That's starting to change. Some of the country's major medical societies pledged this month to cut the misuse of antibiotics in half within four years.  

The problem is that the overuse of antibiotics has actually made them less effective in fighting bacteria. And it has given rise to deadly superbugs, infections that are resistant to most antibiotics.

A dozen medical groups—including the American Medical Association, the American College of Physicians, and the American Academy of Family Physicians—said in a statement that "antibiotic resistance is a major threat to public health." They made a commitment to "preserve these lifesaving therapies for the good of all of our patients."

They were responding to a White House goal, announced in 2015, to reduce inappropriate antibiotic prescribing by 50 percent by 2020.

There are two major reasons the medical community is taking up this issue: 

• The rise of deadly superbugs. Years of overuse have caused bacteria to develop resistance to antibiotics, causing infections that are harder to cure and more costly to treat. For example, a bacterium called staphylococcus aureus (MRSA), which causes respiratory and skin infections, is spreading through households, schools, and the military because it is resistant to most antibiotics.

• Antibiotics can make you sicker. Antibiotic use increases the chances of developing an infection caused by clostridium difficile (C. diff), bacteria that can sometimes result in life-threatening diarrhea. The CDC estimated recently that almost half a million Americans contracted the infection in 2011, resulting in 15,000 deaths. Other side effects include vaginal infections, nausea, swelling of the face and throat, and breathing problems. Some antibiotics can cause permanent nerve damage and torn tendons.

As part of the national Choosing Wisely initiative, specialty societies alarmed by the trend have examined the medical evidence and named several common conditions that you should discuss carefully with your doctor before taking antibiotics.

Consumer Reports, a partner in this effort, has created materials that help you have a conversation with your physician.

Here are six conditions you should question your doctor about before taking antibiotics: 

1. Respiratory Infections

Colds, the flu, and most other respiratory infections are caused by viruses, which generally can't be wiped out by antibiotics. Bronchitis is usually caused by a virus or an irritant in the air like cigarette smoke. Consider antibiotics if a cough doesn’t get better in 14 days, or if the doctor diagnoses a bacterial illness, like strep throat. Instead, ease symptoms by drinking plenty of liquids, breathing moist air, gargling with salt water, and taking acetaminophen (Tylenol and generic) or ibuprofen (Advil and generic).

2. Sinus Infections

Sinusitis is almost always caused by a virus. Symptoms include a stuffy or runny nose and pain in the face. Even when bacteria are the cause, the infections usually clear up on their own in about a week. Consider antibiotics only if you don’t get better after 10 days; you get better and then worse again; or you have a high fever and thick, colored mucus for three or more days in a row. In the meantime, to loosen mucus and help it drain, drink warm liquids; breathe warm, moist air; and keep your head propped up when you lie down.

3. Ear Infections

Most ear infections improve on their own in two or three days, especially in children ages 2 or older. Give your child over-the-counter pain relievers for a few days, and avoid antibiotics. Take him to a doctor if symptoms aren’t better in two to three days or if they worsen. Get antibiotics right away for babies 6 months or younger, for children from 6 months to 2 years old experiencing moderate to severe ear pain, and for children 2 years or older experiencing severe pain.

4. Pinkeye

Pink eye (conjunctivitis) is usually caused by a virus or allergy, so antibiotics won’t help. Even bacterial pinkeye usually goes away on its own within 10 days. Consider antibiotics for bacterial pinkeye if you have a weak immune system, if the condition doesn’t get better in a week without treatment, or if the eye is very swollen or painful or develops a thick, puslike discharge. Soothe pinkeye symptoms with a clean, cool, wet compress. Pinkeye resulting from allergies can be helped with antihistamine eyedrops.

5. Urinary Tract Infections in Older People

Doctors often find bacteria in routine urine tests and then prescribe antibiotics even when patients have no symptoms of a urinary tract infection (UTI). But older people often have bacteria in their urine with no UTI. Consider antibiotics only if the person has UTI symptoms, like pain or burning during urination or a strong urge to go often.

6. Eczema

Eczema causes dry, itchy, red skin. Doctors may try to control it with antibiotics. But antibiotics don’t help the itching, redness, or severity of the condition. To control eczema, moisturize your skin and avoid things that irritate it. Ask your doctor about a medicated cream or ointment to relieve itching and swelling. Consider antibiotics only if there are signs of a bacterial infection, such as bumps full of pus, honey-colored crusting, very red or warm skin, or a fever.

And last, if you're given antibiotics, take them as prescribed. Don’t skip doses or stop taking the medicine early.