Antibiotics are unnecessary and ineffective against certain types of infections, such as viral or fungal infections. Taking antibiotics when they are not necessary may lead to antibiotic resistance.

Antibiotics play an important role in treating, and sometimes helping to prevent, many bacterial infections.

However, bacteria may develop antibiotic resistance if a person takes antibiotics when they are not necessary. Antibiotic resistance can make bacterial infections more difficult to treat.

While antibiotics can effectively treat many infections, they cannot cure all of them. They can only help treat certain bacterial infections. They have no effect on viral infections, fungal infections, and other types of disease.

This article discusses what antibiotics are, when they are unnecessary, what antibiotic resistance is and how it occurs, when antibiotics are necessary, and when to speak with a healthcare professional.

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In 1928, Sir Alexander Fleming discovered penicillin, which first came into use in the Allied military in the 1940s and started to become more widely available in the 1950s.

Since then, researchers have discovered and modified several more antibiotics to help treat bacterial infections such as tuberculosis, cholera, and syphilis.

Antibiotics provide treatment for bacterial infections. They cannot treat viral or fungal infections, such as:

Additionally, antibiotics do not work against COVID-19 infections.

Antibiotics can cause side effects. If a person takes antibiotics when they are not necessary, they can still experience these side effects. Some common side effects of antibiotics include:

More serious side effects of antibiotics include severe allergic reactions and Clostridioides difficile infection.

Some classes of antibiotics have side effects that are unique to their class. For example:

Learn more about the side effects of antibiotics.

In some cases, a doctor may recommend against taking antibiotics for certain bacterial infections as well. For example, a doctor may advise against using antibiotics for certain ear infections and sinus infections because they will likely get better on their own.

A doctor may instead recommend watchful waiting. This is when a healthcare professional watches someone for 2–3 days to find out whether the immune system will fight off the infection without antibiotics.

People may also hear healthcare professionals use the term “antibiotic misuse,” which refers to instances when a doctor has prescribed:

  • the wrong dose of an antibiotic
  • an antibiotic for the wrong length of time
  • the wrong type of antibiotic, as not all antibiotics work against all bacteria

Some antibiotics have a broad spectrum of coverage, meaning they can work against many different types of bacteria. However, becoming overly reliant on broad-spectrum antibiotics means that bacteria may be able to adapt and resist treatment.

Protocol in healthcare institutions suggests using narrow-spectrum antibiotics when appropriate to help reduce the risk of this.

Overusing antibiotics can lead to bacterial infections with antibiotic resistance. This means that the bacteria no longer respond to antibiotics. The bacteria may then spread to other individuals and cause potentially life threatening infections.

Antibiotic resistance can occur due to the following:

  • Acquired resistance: This is when bacteria develop resistance due to a genetic mutation.
  • Intrinsic resistance: This is when evolutionary changes to the structure of the bacteria can help them survive antibiotic use.
  • DNA transfer: This is when a bacterium acquires DNA changes from another bacterium that is already antibiotic-resistant.
  • Genetic change: This is when bacteria develop different structures and receptors, so the antibiotics cannot recognize the bacteria.

Carbapenems, a powerful class of broad-spectrum antibiotics, are widely used in hospitals as they cover a wide spectrum of bacteria.

Enterobacterales are a large group of bacteria that cause infections in healthcare settings. Enterobacterales continuously develop and find new ways to resist antibiotic treatment, resulting in the development of carbapenem-resistant Enterobacterales (CRE) — very strong bacterial strains that are resistant to powerful antibiotics. Experts consider CREs a threat to public health.

By reducing unnecessary antibiotic use, individuals may help to slow the development of new strains of antibiotic-resistant bacteria. This can help researchers keep up with the demand to develop new antibiotics and other potential treatments for antibiotic-resistant bacteria.

The author of a 2016 article warns that continued increases in antibiotic resistance may lead to worse infections than people experienced before the development of antibiotics.

Antibiotics can provide effective treatment for certain life threatening or serious bacterial infections. According to the Centers for Disease Control and Prevention (CDC), a doctor is likely to prescribe antibiotics for health conditions including:

Many other infections may require antibiotics as well. A person can ask a healthcare professional whether antibiotics would help to treat any current infections they have.

A person should consider contacting a healthcare professional if they develop an infection that does not go away or get better after a few days.

For example, individuals should consider speaking with a doctor if they show signs of a UTI. These can include:

Common signs of strep throat include:

A doctor can make a diagnosis and help determine whether a person needs antibiotics. A person with a cold, flu, or other viral infection should not take antibiotics.

Antibiotics can be an effective treatment for bacterial infections. However, they are not necessary for viral infections, fungal infections, and certain bacterial infections, such as sinus infections and some ear infections. Individuals should only take antibiotics when told to do so by a doctor.

A person may experience side effects from taking antibiotics, and unnecessary antibiotic use can contribute to the development of antibiotic-resistant bacteria.

Doctors often reserve the use of antibiotics for only certain bacterial infections. These may include UTIs, strep throat, and whooping cough. A healthcare professional can determine whether an infection requires antibiotics.