What you need to know about antibiotics

Antibiotics, also known as antibacterial, are medicines which destroy or delay bacterial growth.

They include a range of potent drugs and are used to combat bacteria-induced diseases.

Antibiotics are unable to treat viral infections, including colds, flu, and most coughs.

The article explains what antibiotics are, how they act, any possible side effects and the resistance to antibiotics.

Fast facts about antibiotics

  • Alexander Fleming discovered penicillin, the first natural antibiotic, in 1928.
  • Antibiotics can not fight viral infections.
  • Fleming predicted the rise of antibiotic resistance.
  • Antibiotics either kill or slow the growth of bacteria.
  • Side effects can include diarrhea, an upset stomach, and nausea.

What are antibiotics?


Antibiotics are powerful medicines that combat certain infections and, when properly used, can save lives. They either stop reproducing bacteria, or they destroy them.

The immune system can typically kill them, before bacteria can multiply and cause symptoms. White blood cells (WBCs) attack harmful bacteria, and the immune system can usually cope with and fight off the infection, even if symptoms do occur.

However, sometimes the number of harmful bacteria is excessive, and the immune system can’t fight all of them. In this scenario antibiotics are helpful.

Penicillin was the first antibiotic. Antibiotics dependent on penicillin, such as ampicillin, amoxicillin, and penicillin G, are still available for the treatment of a number of infections and have been around for long.

There are many forms of modern antibiotics available, and in most countries, they are usually only used with a prescription. Topical antibiotics are available in creams and ointments formulated with over- the-counter (OTC).


Most medical practitioners have concerns about overuse of antibiotics by humans. I also claim this overuse leads to the increasing number of bacterial infections that become immune to antibacterial drugs.

Outpatient antibiotic overuse is a particular problem according to the Centers for Disease Control (CDC). For certain region, such as the Southeast, antibiotic use appears to be greater.

The use of carbapenems, a large class of last-line antibiotics, increased substantially between 2007 and 2010.

Alexander Fleming, speaking in his Nobel Prize acceptance speech in 1945, 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 expected by the man who discovered the first antibiotic nearly 70 years ago, drug resistance is beginning to get widespread.

How do antibiotics work?

There are different types of antibiotic, which 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.


A doctor is administering antibiotics to treat a bacterial infection. This is ineffective against viruses.

Understanding whether a bacterial or viral infection is helpful in the effective treatment of it.

Many upper respiratory tract infections (URTIs), including common cold and flu, are caused by viruses. Such viruses don’t work against antibiotics.

If people overuse or misuse antibiotics, then the bacteria may become resistant. It means the antibiotic becomes less effective against that form of bacterium, as the bacterium has strengthened its defenses.

A doctor can prescribe a wide-spectrum antibiotic to treat a variety of infections. A narrow spectrum antibiotic is effective only against a few bacterial types.

Aerobic bacteria are attacked by some antibiotics while others function against anaerobic bacteria. Aerobic bacteria do not require oxygen, nor anaerobic bacteria.

In some cases, a healthcare professional may provide antibiotics to prevent an infection rather than treat it, as may be the case before surgery. It is the use of antibiotics as’ prophylactic.’ These antibiotics are widely used in humans 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 vagina

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, particularly older adults, can experience inflammation of the intestine which can lead to severe, bloody diarrhea.

Penicillins, cephalosporins, and erythromycin may also cause inflamed bowels in less frequent instances.


Some people, particularly penicillins, can develop an allergic reaction to the antibiotics. Side effects could include a rash, tongue and face swelling and breathing difficulties.

Hypersensitivity reactions to allergic antibiotics could be severe or delayed.

Anyone who has an allergic reaction to an antibiotic will notify their pharmacist or doctor. Antibiotic responses can be severe and sometimes fatal. Their reactions are called anaphylactic.

Persons with decreased funtion in the liver or kidney should be vigilant when taking antibiotics. This can affect the antibiotic types they can use, or the dose they receive.

Women who are pregnant or breast-feeding will also talk to a doctor about the right medications to be taken.


Individuals taking an antibiotic should not take any medical products or herbal remedies without first talking to a doctor. Some OTC medicines can interact with antibiotics, too.

Some doctors suggest antibiotics can decrease the effectiveness of oral contraceptives. But reserch is usually not supportive of this.

Nevertheless, people who experience diarrhea and vomiting or do not take their oral contraceptive during illness due to an upset stomach may find their efficacy is declining.

Take additional care about abortion in these situations.

How to use

People take antibiotics typically by mouth. Nevertheless, doctors may prescribe them by injection or directly apply them to the part of the infected body.

Within a few hours most antibiotics begin fighting infection. Finish the entire course of the drug to prevent the infection returning.

Stoping the drug before the course is over increases the risk of the bacteria being immune to potential therapies. Those who live will have had some antibiotic exposure and may develop resistance to it as a consequence.

patient needs to complete the antibiotic treatment course even after seeing symptoms improve.

Do not take other foods and drinks with antibiotics. Take on an empty stomach for others, about an hour before meals, or 2 hours after. For the drug to be safe follow the instructions correctly. People who take metronidazole should not be alcohol-drinking.

Avoid dairy products when taking tetracyclines, as these may interfere with the medication’s absorption


Are there any bacteria that are resistant to all antibiotics?


There are several different types of antibiotic resistant bacteria that have been the most effective against them. Such examples include:

  • ethicillin-resistant Staphylococcus aureus (MERSA); multi-drug-resistant Mycobacterium tuberculosis (MDR-TB)
  • carbapenem-resistant Enterobacteriaceae (CRE) gut bacteria
  • vancomycin-resistant Enterococcus (VRE)

It can be very difficult, if not impossible, to treat when one of those bacteria triggers an infection.

——-Alan Carter, PharmD

Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.


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