Antibiotics: What You Need to Know

Antibiotics, also known as antibacterials, are medications that destroy or slow down the growth of bacteria.

They include a range of powerful drugs and are used to treat diseases caused by bacteria. Antibiotics cannot treat viral infections, such as colds, flu, and most coughs.

This article will explain what antibiotics are, how they work, any potential side effects, and antibiotic resistance.

Fast facts on antibiotics

  • Penicillin, the first natural antibiotic, was discovered by Alexander Fleming in 1928.
  • Antibiotics are ineffective against viral infections.
  • Antibiotic resistance was anticipated by Fleming.
  • Antibiotics either kill or slow bacteria’s growth.
  • Diarrhea, stomach distress, and nausea are all possible side effects.

What are antibiotics?

Antibiotics are a common medication that doctors prescribe to fight bacteria. Antibiotics are potent drugs that combat infections and, when taken correctly, can save lives. They either prevent bacteria from multiplying or kill them.

The immune system can usually eliminate bacteria before they grow and produce symptoms. White blood cells (WBCs) destroy harmful germs, and even if symptoms appear, the immune system is typically able to manage and combat the infection.

However, there are occasions when the number of hazardous germs is excessive, and the immune system is unable to combat them all. Antibiotics can be in handy in this situation.

Penicillin was the first antibiotic. Ampicillin, amoxicillin, and penicillin G are penicillin-based antibiotics that have been around for a long time and are still used to treat a range of infections.

Several types of modern antibiotics are available, and they are usually only available with a prescription in most countries. Topical antibiotics are available in over-the-counter (OTC) creams and ointments.


Some medical professionals have concerns that people are overusing antibiotics. They also believe that this overuse contributes to the growing number of bacterial infections that are becoming resistant to antibacterial medications.

According to the Centers for Disease Control (CDC), outpatient antibiotic overuse is a particular problem. Antibiotic use appears to be higher in some regions, such as the Southeast.

The use of carbapenems, a major class of last-line antibiotics, increased significantly from 2007 to 2010. Speaking in his Nobel Prize acceptance speech in 1945, Alexander Fleming said

“Then there is the danger that the ignorant man may easily underdose himself and by exposing his microbes to non-lethal quantities of the drug, make them resistant.”

As the man who discovered the first antibiotic almost 70 years ago predicted, drug resistance is starting to become commonplace.

How do antibiotics work?

There are different types of antibiotics that work in one of two ways:

  • A bactericidal antibiotic, such as penicillin, kills the bacteria. These drugs usually interfere with either the formation of the bacterial cell wall or its cell contents.
  • A bacteriostatic stops bacteria from multiplying.


Antibiotics are ineffective against viruses. A doctor prescribes antibiotics for the treatment of a bacterial infection. It is not effective against viruses. Knowing whether an infection is bacterial or viral helps to effectively treat it.

Most upper respiratory tract infections (URTIs), such as the common cold and flu, are caused by viruses. Antibiotics have no effect on these viruses.

Bacteria may grow resistant to antibiotics if they are overused or used inappropriately. This means that when the bacterium’s defenses increase, the antibiotic becomes less effective against that type of bacterium.

A broad-spectrum antibiotic can be prescribed by a doctor to treat a variety of ailments. Only a few species of bacteria are effective against a narrow-spectrum antibiotic.

Some antibiotics are effective against aerobic bacteria, whereas others are effective against anaerobic bacteria. Anaerobic bacteria do not require oxygen, whereas aerobic bacteria do.

Antibiotics may be prescribed by a healthcare provider to prevent rather than treat an illness in some instances.

This is the ‘prophylactic’ use of antibiotics. People commonly use these antibiotics before bowel and orthopedic surgery.

Side effects

Antibiotics commonly cause the following side effects:

  • diarrhea
  • nausea
  • vomiting
  • rash
  • upset stomach
  • With certain antibiotics or prolonged use, fungal infections of the mouth, digestive tract, and vaginal

Less common side effects of antibiotics include:

  • formation of kidney stones when taking sulphonamides
  • abnormal blood clotting when taking some cephalosporins.
  • sensitivity to sunlight when taking tetracyclines
  • blood disorders when taking trimethoprim
  • deafness,
    when taking erythromycin and the aminoglycosides

Some people, especially older adults, may experience bowel inflammation, which can lead to severe, bloody diarrhea. In less common instances, penicillins, cephalosporins, and erythromycin can also cause inflamed bowels.


Some people may develop an allergic reaction to antibiotics, especially penicillin. Side effects might include a rash, swelling of the tongue and face, and difficulty breathing. Allergic reactions to antibiotics might be immediate or delayed.

Anyone who has an allergic reaction to an antibiotic must tell their doctor or pharmacist. Reactions to antibiotics can be serious and sometimes fatal. They are called anaphylactic reactions.

People with reduced liver or kidney function should be cautious when using antibiotics. This may affect the types of antibiotics they can use or the dose they receive.

Likewise, women who are pregnant or breastfeeding should speak with a doctor about the best antibiotics to take.


Individuals taking an antibiotic should not take other medicines or herbal remedies without speaking with a doctor first. Certain OTC medicines might also interact with antibiotics.

Some doctors suggest that antibiotics can reduce the effectiveness of oral contraceptives. However, research generally does not support this.

Nonetheless, people who experience diarrhea and vomiting or are not taking their oral contraceptive during illness because of an upset stomach might find that its effectiveness is reduced. In these circumstances, take additional contraceptive precautions.

How to use

People must not stop a course of antibiotics halfway through. If in doubt, they can ask their doctor for advice.

People usually take antibiotics by mouth. However, doctors can administer them by injection or apply them directly to the part of the body with infection.

Most antibiotics start combating infection within a few hours. Complete the whole course of medication to prevent the return of the infection.

Stopping the medication before the course has finished increases the risk that the bacteria will become resistant to future treatments. The ones that survive will have had some exposure to the antibiotic and may consequently develop resistance to it.

An individual needs to complete the course of antibiotic treatment even after they see an improvement in symptoms.

Do not take some antibiotics with certain foods and drinks. Take others on an empty stomach, about an hour before meals, or 2 hours after. Follow the instructions correctly for the medication to be effective. People taking metronidazole should not drink alcohol.

Avoid dairy products when taking tetracyclines, as they might disrupt the absorption of the medication.

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