6 things you should know about antibiotics

Created 28 October 2021
Updated 15 July 2024

About this article

Created 28 October 2021
Updated 15 July 2024

1. Antibiotics save lives 

Since the discovery of penicillin in 1928, the widespread use of antibiotics has saved millions of lives. The main weapon in the fight against bacterial infections, antibiotics, alongside vaccinations, have added nearly twenty years to life expectancy.1  

2. Antibiotics destroy species responsible for infections, but also eliminate good bacteria

Gut, vagina, lungs, skin... many parts of the body play host to microorganisms (bacteria, fungi, viruses). Such microbial communities are known as microbiota.2 Antibiotics eradicate pathogenic germs responsible for infection but can also destroy certain beneficial bacteria in our microbiota, leading to imbalances ( (sidenote: Dysbiosis Generally defined as an alteration in the composition and function of the microbiota caused by a combination of environmental and individual-specific factors. Levy M, Kolodziejczyk AA, Thaiss CA, et al. Dysbiosis and the immune system. Nat Rev Immunol. 2017;17(4):219-232.   ) 3) of varying degrees within these ecosystems. This concerns all of the body’s microbiota, including: the gut, skin,4 lung,5 ENT,6 urinary,7 and vaginal microbiota.8 

The ambivalent role of antibiotics

By destroying the bacteria responsible for infection, antibiotics can also lead…

3. Antibiotics can have side effects 

By inducing a dysbiosis, antibiotics can have harmful effects on health. The main short-term complication is the alteration of bowel movements experienced by some patients. This most often results in diarrhea, with the gut microbiota less able to perform its protective functions. Antibiotic-associated diarrhea is usually mild to moderate9 in intensity, but its incidence varies according to age, type of antibiotic, context, etc. It may affect up to 35%9,10,11 of patients and 80% of children.9 In 10%-20% of cases, the diarrhea results from an infection by Clostridioides difficile (C. difficile),11 a bacterium that colonizes the gut microbiota and becomes pathogenic due to certain factors (e.g. antibiotic use). The clinical consequences vary, ranging from moderate diarrhea to much more serious symptoms, or even death.11 


35% It may affect up to 35% of patients

80% and 80% of children

4. Antibiotics are thought to be responsible for longer-term effects

Diarrhea is not the only symptom of antibiotic-associated dysbiosis. When it occurs early in life, the condition is thought to be responsible for longer-term effects. The perinatal period, characterized by the development of the gut microbiota and the maturation of the immune system, is a particularly sensitive period.12 Antibiotic-associated dysbiosis during this phase seems to be a risk factor in the development of certain chronic diseases (obesity, diabetes mellitus, asthma, inflammatory bowel disease).13 

 5. Inappropriate use of antibiotics is responsible for antibiotic resistance 

Antibiotic resistance happens when an antibiotic treatment is no longer effective against a bacterial infection.1 The cause? Antibiotics are only effective against bacteria and have no effect on viruses (e.g. the flu).14 The inappropriate (e.g. with viral infections) or excessive use of antibiotics – in humans or animals – accelerates antibiotic resistance. Antibiotic resistance leads to longer hospitalizations, higher health care costs and more deaths. For this reason, the issue has become a major public health concern worldwide.1

6. World Antimicrobial Awareness Week 

Each year, from November 18 to 24, the WHO organizes World AMR Awareness Week, which aims to increase awareness of global (sidenote: Antimicrobial Class of drugs that includes antibiotics (active against bacteria), antiviral agents (active against virus), antiparasitic agents (active against parasites), and antifungal agents (active against fungi). WHO Antimicrobial Resistance; Oct 2020 ) resistance and to encourage best practices among the general public, health workers and policymakers to avoid the further emergence and spread of drug-resistant infections. As an expert on microbiota, the Biocodex Microbiota Institute takes part in this initiative.

Infographics to share with your patients

What is the World AMR Awareness Week?

Each year, since 2015, the WHO organizes the World AMR Awareness Week (WAAW), which aims to increase awareness of global antimicrobial resistance.
Held on 18-24 November, this campaign encourages the general public, healthcare professionals and decision-makers to use antimicrobials carefully, to prevent the further emergence of antimicrobial resistance.


1. WHO Antimicrobial Resistance; Oct 2020; https://www.who.int/news-room/fact-sheets/detail/antimicrobial-resistance 

2. Kho ZY, Lal SK. The Human Gut Microbiome - A Potential Controller of Wellness and Disease. Front Microbiol. 2018 Aug 14;9:1835. 

3. Levy M, Kolodziejczyk AA, Thaiss CA, et al. Dysbiosis and the immune system. Nat Rev Immunol. 2017;17(4):219-232. 

4. Park SY, Kim HS, Lee SH, et al. Characterization and Analysis of the Skin Microbiota in Acne: Impact of Systemic Antibiotics. J Clin Med. 2020;9(1):168. 

5. Chung KF. Airway microbial dysbiosis in asthmatic patients: A target for prevention and treatment? J Allergy Clin Immunol. 2017;139(4):1071- 1081. 

6. Teo SM, Mok D, Pham K, et al. The infant nasopharyngeal microbiome impacts severity of lower respiratory infection and risk of asthma development. Cell Host Microbe. 2015;17(5):704-715. 

7. Klein RD, Hultgren SJ. Urinary tract infections: microbial pathogenesis, host-pathogen interactions and new treatment strategies. Nat Rev Microbiol. 2020;18(4):211-226. 

8. Shukla A, Sobel JD. Vulvovaginitis Caused by Candida Species Following Antibiotic Exposure. Curr Infect Dis Rep. 2019 Nov 9;21(11):44. 

9. McFarland LV, Ozen M, Dinleyici EC et al. Comparison of pediatric and adult antibiotic-associated diarrhea and Clostridium difficile infections. World J Gastroenterol. 2016;22(11):3078-3104. 

10. Bartlett JG. Clinical practice. Antibiotic-associated diarrhea. N Engl J Med2002;346:334-9.

11. Theriot CM, Young VB. Interactions Between the Gastrointestinal Microbiome and Clostridium difficile.Annu Rev Microbiol. 2015;69:445-461.  

12. Aires J. First 1000 Days of Life: Consequences of Antibiotics on Gut Microbiota. Front Microbiol. 2021 May 19; 

13. Queen J, Zhang J, Sears CL. Oral antibiotic use and chronic disease: long-term health impact beyond antimicrobial resistance and Clostridioides difficile. Gut Microbes. 2020;11(4):1092-1103

14. Centers for Disease Control and Prevention; Patient Education and Promotional Resources https://www.cdc.gov/antibiotic-use/community/pdfs/aaw/au_improving-antibiotics-infographic_8_5x11_508.pdf 

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