Antibiotics: When They Can and Can't Help

What are antibiotics?

Antibiotics are strong medicines used to treat infections, including life-threatening contagious diseases. But antibiotics can cause more harm than good when they aren't used the right way. You can protect yourself and your family by knowing when you should use antibiotics and when you should not.

Do antibiotics work against all infections?

No. Antibiotics only work against infections caused by bacteria, fungi and certain parasites. They don't work against any infections caused by viruses. Viruses cause colds, the flu and most coughs and sore throats.

What is "antibiotic resistance?"

“Antibiotic resistance” and “bacterial resistance” are two ways of describing the same thing. Usually, antibiotics kill bacteria or stop them from growing. However, some bacteria have become resistant to some types of antibiotics. This means that the antibiotics no longer work against them. Bacteria become resistant more quickly when antibiotics are used too often or are not used correctly (such as not taking a full course of antibiotics as prescribed by your doctor).

Bacteria that are resistant to one antibiotic can sometimes be treated with other antibiotics. These other medicines may have to be given intravenously (through a vein) in a hospital. A few kinds of bacteria are resistant to all antibiotics and are now untreatable.

What can I do to help myself and my family?

Do not expect antibiotics to cure every illness. Do not take antibiotics for viral illnesses, such as for colds or the flu. Often, the best thing you can do is let colds and the flu run their course. Sometimes this can take 2 weeks or more. If your illness gets worse after 2 weeks, talk to your doctor. He or she can also give you advice on what you can do to relieve your symptoms while your body fights off the virus.

How do I know when I need antibiotics?

The answer depends on what is causing your infection. The following are some basic guidelines:

• Colds and flu. Viruses cause these illnesses. They can't be cured with antibiotics.

• Cough or bronchitis. Viruses almost always cause these. However, if you have a problem with your lungs or an illness that lasts a long time, bacteria may actually be the cause. Your doctor may decide to try using an antibiotic.

• Sore throat. Most sore throats are caused by viruses and don't need antibiotics. However, strep throat is caused by bacteria. Your doctor can determine if you have strep throat and can prescribe an antibiotic.

• Ear infections. There are several types of ear infections. Antibiotics are used for some (but not all) ear infections.

• Sinus infections. Antibiotics are often used to treat sinus infections. However, a runny nose and yellow or green mucus do not necessarily mean you need an antibiotic.  Read more about treating sinusitis.

What else do I need to know?

If your doctor does prescribe an antibiotic for you, make sure you take all of the medicine, even if you feel better after a few days. This reduces the chance that there will be any bacteria left in your body that could potentially become resistant to antibiotics.

Never take antibiotics without a prescription. If, for whatever reason, you have antibiotics leftover from a time when you were previously sick, do not take them unless your doctor tells you it's okay. The leftover antibiotics may not work on whatever is making you sick. If they do work, there probably will not be enough leftover medicine to completely kill all the bacteria in your body. Not only will you not get better, but this increases the chance that the bacteria will become resistant to antibiotics.

You can prevent catching infections in the first place by practicing good hygiene. Wash your hands with soap and water, especially after using the restroom, coming into contact with feces (for example, from a pet or from changing a baby's diaper) and before eating.

Written by familydoctor.org editorial staff

Reviewed/Updated: 05/14

Created: 05/01