Table of ContentsView AllTable of ContentsWhat Is An Antibiotic?How Do Antibiotics Work?How Long Do They Take to Work?UsesSide EffectsAntibiotic ResistanceWhen to Seek HelpFrequently Asked Questions
Table of ContentsView All
View All
Table of Contents
What Is An Antibiotic?
How Do Antibiotics Work?
How Long Do They Take to Work?
Uses
Side Effects
Antibiotic Resistance
When to Seek Help
Frequently Asked Questions
This article will explore how antibiotics work, what they are used to treat, and how quickly they can help end an infection.
Every Antibiotics Question You Have, Answered
Verywell / Theresa Chiechi
Antibiotics are substances that get their start in nature, usually as fungi or other forms of bacteria that exist in soils. These substances are able to bind to the cell walls of harmful bacteria, penetrating the cell to either kill the bacteria or prevent it from reproducing.
British scientist Alexander Fleming developed penicillin in the late 1920s after noticing that a mold growing on the same plate asStaphylococcus aureasbacteria was destroying the bacteria. He determined that the Penicillum mold created a substance that could dissolve bacteria, and over the next several decades penicillins were increasingly used to treat a variety of infections.
Antibiotic development exploded after World War II, and today there are several classes of antibiotics to choose from. Each has its own place in treating bacterial infections, with some used to attack a wide range of bacteria while others have more specialized uses.
Different types of antibiotics work against bacteria in different ways. Below are some examples.Antibiotics that destroy cell wallsBeta-lactam antibioticsGlycopeptidesAntibiotics that alter genetics of the bacteriaTetracyclinesMacrolidesOxazolidinonesAntibiotics that prevent bacteria from reproducingQuinilonesSulfonamides
Different types of antibiotics work against bacteria in different ways. Below are some examples.
Antibiotics that destroy cell walls
Antibiotics that alter genetics of the bacteria
Antibiotics that prevent bacteria from reproducing
Some antibiotics work best on certain types of bacteria. Mainly, these are classified as antibiotics that targetgram-positive bacteriawith a simple cell wall, and those that target the more complex gram-negative bacteria.
Your healthcare provider may treat you with a broad-spectrum antibiotic that works against both gram-positive and gram-negative bacteria, but some infections may require aculturetest to identify the specific form of bacteria. By identifying the exact type of bacteria that’s causing your illness, your healthcare provider can prescribe you the form of antibiotic that’s most effect against that particular bacteria.
How long antibiotics take to work depends on the infection being treated and what type of antibiotic you are taking. Some antibiotics achieve their maximum effect with high concentrations, and these may be given in the form of intravenous infusions. Other types of antibiotics are more effective over time.
For example, levofloxacin is in the fluoroquinolone class of antibiotics and it reaches its peak performance based on concentration.It is a stronger antibiotic that begins to work in hours, but can take days to completely cure an infection.
On the other hand, penicillin works over a period of time. Depending on how your illness has spread, it can take days or even weeks to work completely. For example, when used to treatstrep throat, penicillin can make you non-infectious to others in about a day, but you may need to keep taking medication for several days to resolve your own infection.
How Long Do Antibiotics Stay in Your System?
Antibiotics only work against bacterial infections, and certain antibiotics are only effective at fighting very specific types of bacteria.
Gram-positive bacteria have a simple cell wall, but gram-negative bacteria are surrounded with an additional layer that is more difficult for antibiotics to penetrate. Antibiotics are usually prescribed as either broad-spectrum—meaning they can treat both types of bacteria, or they are prescribed specifically for the type of bacteria that is causing your infection.
Other antibiotics like amoxicillin, ampicillin,cephalosporins, and fluoroquinolones can treat a variety of both gram-positive and gram-negative infections includingsepsisandurinary tract infections.
What Are the Best Antibiotics to Treat Pneumonia?
Antibiotics Are Not a Cure-AllAntibiotics should only be used for specific bacterial infections. Taking antibiotics only when appropriate can help fight antimicrobial resistance. AntibioticsDO NOT workagainst viruses and cannot be used to treat infections likeinfluenzaorCOVID-19.You should also be sure to always take your full course of antibiotics. Don’t save them in case you get sick later—antibiotics you take for one infection may not work on another. You should also never share your antibiotics with anyone else or use antibiotics that were not prescribed to you.
Antibiotics Are Not a Cure-All
Antibiotics should only be used for specific bacterial infections. Taking antibiotics only when appropriate can help fight antimicrobial resistance. AntibioticsDO NOT workagainst viruses and cannot be used to treat infections likeinfluenzaorCOVID-19.You should also be sure to always take your full course of antibiotics. Don’t save them in case you get sick later—antibiotics you take for one infection may not work on another. You should also never share your antibiotics with anyone else or use antibiotics that were not prescribed to you.
Antibiotics should only be used for specific bacterial infections. Taking antibiotics only when appropriate can help fight antimicrobial resistance. AntibioticsDO NOT workagainst viruses and cannot be used to treat infections likeinfluenzaorCOVID-19.
You should also be sure to always take your full course of antibiotics. Don’t save them in case you get sick later—antibiotics you take for one infection may not work on another. You should also never share your antibiotics with anyone else or use antibiotics that were not prescribed to you.
Side effects of antibiotics can vary depending on the type of antibiotic you are taking, what dose you were prescribed, and what other health issues you may have.Some other medicationscan affect how well your antibiotics work and what side effects you develop.
Alcohol and AntibioticsAlcohol use is not recommended to be taken with most medications—including antibiotics—over concerns that alcohol use with these medications can reduce how well they work and increase their toxicity. There are warnings against alcohol use with several specific types of antibiotics like doxycycline and cephalosporins, but the science behind these recommendations has recently come into question.A 2020 paper reviewed the data behind these recommendations and found that most studies of combined alcohol and antibiotic use were limited and focused mainly on antibiotic use in alcoholics and people who consumed large amounts of alcohol. Few studies investigated the effect of social or limited alcohol consumption while taking antibiotics.While the paper raised questions about the true dangers of alcohol use with antibiotics, the authors recommended that alcohol should still be avoided with antibiotic use until more research can be done.
Alcohol and Antibiotics
Alcohol use is not recommended to be taken with most medications—including antibiotics—over concerns that alcohol use with these medications can reduce how well they work and increase their toxicity. There are warnings against alcohol use with several specific types of antibiotics like doxycycline and cephalosporins, but the science behind these recommendations has recently come into question.A 2020 paper reviewed the data behind these recommendations and found that most studies of combined alcohol and antibiotic use were limited and focused mainly on antibiotic use in alcoholics and people who consumed large amounts of alcohol. Few studies investigated the effect of social or limited alcohol consumption while taking antibiotics.While the paper raised questions about the true dangers of alcohol use with antibiotics, the authors recommended that alcohol should still be avoided with antibiotic use until more research can be done.
Alcohol use is not recommended to be taken with most medications—including antibiotics—over concerns that alcohol use with these medications can reduce how well they work and increase their toxicity. There are warnings against alcohol use with several specific types of antibiotics like doxycycline and cephalosporins, but the science behind these recommendations has recently come into question.
A 2020 paper reviewed the data behind these recommendations and found that most studies of combined alcohol and antibiotic use were limited and focused mainly on antibiotic use in alcoholics and people who consumed large amounts of alcohol. Few studies investigated the effect of social or limited alcohol consumption while taking antibiotics.
While the paper raised questions about the true dangers of alcohol use with antibiotics, the authors recommended that alcohol should still be avoided with antibiotic use until more research can be done.
Most side effects of antibiotics stem from the fact that they may not only target the bacteria causing your infection. Antibiotics can kill"good" bacteriaand upset the natural balance in your body, especially in the gut. The use of probiotics while taking antibiotics may be helpful in reducing some of these side effects.
Common side effects of antibiotics include:
If you experience things like shortness of breath, hives, or other symptoms of allergic reaction, stop taking your antibiotic and call you healthcare provider immediately.
Common and Serious Antibiotic Side Effects in Children
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When to See a Healthcare Professional
You should only take antibiotics under the direction of a healthcare professional. If your symptoms worsen or aren’t resolved after your full course of antibiotics, talk to your healthcare provider about additional treatment options.
You should also alert your healthcare provider to any side effects you experience while taking antibiotics, even if they are minor. Go the emergency room or seek immediate medical care if you experience symptoms of anallergic reactionwhile taking antibiotics.
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Can Probiotics Treat or Prevent Bacterial Infections?
Frequently Asked QuestionsIt’s not recommended to drink alcohol with antibiotics—and particularly with certain varieties. Talk to your doctor of pharmacist about the specific antibiotic you were prescribed and how it may interact with alcohol. It’s also a good idea to review the effects of alcohol on any other medications you may be taking, too.Learn MoreZorvolex (Diclofenac) and AlcoholWhile the science behind the recommendation to avoid drinking alcohol while taking antibiotics has been debated, its generally believed that alcohol can reduce how well antibiotics work and increase toxicity levels. You may experience things like increased nausea or vomiting when combining antibiotics with alcohol.A urinary tract infection may resolve on its own without the use of antibiotics, but antibiotics can help decrease the length of your infection and help prevent complications. A UTI can be treated within a few days with antibiotics, but can last much longer without. Even worse, an untreated UTI can lead to more severe illness like kidney infections or even urosepsis.Learn MoreSymptoms of a Urinary Tract InfectionHow long antibiotics stay in your system depends on the type of antibiotic you are taking. Some last as little as a few hours after your last dose while others can stay in your system for weeks. Types of antibiotics that last the longest in your body include certain types of penicillins and hydroxychloroquine.Learn MoreAntibiotics for Treating Infections
It’s not recommended to drink alcohol with antibiotics—and particularly with certain varieties. Talk to your doctor of pharmacist about the specific antibiotic you were prescribed and how it may interact with alcohol. It’s also a good idea to review the effects of alcohol on any other medications you may be taking, too.Learn MoreZorvolex (Diclofenac) and Alcohol
It’s not recommended to drink alcohol with antibiotics—and particularly with certain varieties. Talk to your doctor of pharmacist about the specific antibiotic you were prescribed and how it may interact with alcohol. It’s also a good idea to review the effects of alcohol on any other medications you may be taking, too.
Learn MoreZorvolex (Diclofenac) and Alcohol
While the science behind the recommendation to avoid drinking alcohol while taking antibiotics has been debated, its generally believed that alcohol can reduce how well antibiotics work and increase toxicity levels. You may experience things like increased nausea or vomiting when combining antibiotics with alcohol.
A urinary tract infection may resolve on its own without the use of antibiotics, but antibiotics can help decrease the length of your infection and help prevent complications. A UTI can be treated within a few days with antibiotics, but can last much longer without. Even worse, an untreated UTI can lead to more severe illness like kidney infections or even urosepsis.Learn MoreSymptoms of a Urinary Tract Infection
A urinary tract infection may resolve on its own without the use of antibiotics, but antibiotics can help decrease the length of your infection and help prevent complications. A UTI can be treated within a few days with antibiotics, but can last much longer without. Even worse, an untreated UTI can lead to more severe illness like kidney infections or even urosepsis.
Learn MoreSymptoms of a Urinary Tract Infection
How long antibiotics stay in your system depends on the type of antibiotic you are taking. Some last as little as a few hours after your last dose while others can stay in your system for weeks. Types of antibiotics that last the longest in your body include certain types of penicillins and hydroxychloroquine.Learn MoreAntibiotics for Treating Infections
How long antibiotics stay in your system depends on the type of antibiotic you are taking. Some last as little as a few hours after your last dose while others can stay in your system for weeks. Types of antibiotics that last the longest in your body include certain types of penicillins and hydroxychloroquine.
Learn MoreAntibiotics for Treating Infections
13 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Microbiology Society.Antibiotics.HealthyChildren.org.The history of antibiotics.Kapoor G, Saigal S, Elongavan A.Action and resistance mechanisms of antibiotics: A guide for clinicians.J Anaesthesiol Clin Pharmacol. September 2017;33(3):300-305. doi:10.4103/joacp.JOACP_349_15.Eyler RF, Shvets K.Clinical pharmacology of antibiotics.CJASN. July 2019; 14(7):1080-1090. doi:10.2215/CJN.08140718.SingleCare.What is levofloxacin and what is it used for?Centers for Disease Control and Prevention.About strep throat.Lyme Disease Association of Southeastern Pennsylvania.Antibiotics.U.S. Food and Drug Administration.Combating antibiotic resistance.MedlinePlus.Antibiotics.Mergenhagen KA, et al.Fact versus fiction: A review of the evidence behind alcohol and antibiotic interactions.Antimicrob Agents Chemother.February 2020;64(3). doi:10.1128/AAC.02167-19.Ramirez J, et al.Antibiotics as major disruptors of gut microbiota.Front Cell Infect Microbiol. September 2020;10:731. doi:10.3389/fcimb.2020.572912.Centers for Disease Control and Prevention.Antibiotic use and antimicrobial resistance facts.Unity Point Health.Can UTIs go away on their own?
13 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Microbiology Society.Antibiotics.HealthyChildren.org.The history of antibiotics.Kapoor G, Saigal S, Elongavan A.Action and resistance mechanisms of antibiotics: A guide for clinicians.J Anaesthesiol Clin Pharmacol. September 2017;33(3):300-305. doi:10.4103/joacp.JOACP_349_15.Eyler RF, Shvets K.Clinical pharmacology of antibiotics.CJASN. July 2019; 14(7):1080-1090. doi:10.2215/CJN.08140718.SingleCare.What is levofloxacin and what is it used for?Centers for Disease Control and Prevention.About strep throat.Lyme Disease Association of Southeastern Pennsylvania.Antibiotics.U.S. Food and Drug Administration.Combating antibiotic resistance.MedlinePlus.Antibiotics.Mergenhagen KA, et al.Fact versus fiction: A review of the evidence behind alcohol and antibiotic interactions.Antimicrob Agents Chemother.February 2020;64(3). doi:10.1128/AAC.02167-19.Ramirez J, et al.Antibiotics as major disruptors of gut microbiota.Front Cell Infect Microbiol. September 2020;10:731. doi:10.3389/fcimb.2020.572912.Centers for Disease Control and Prevention.Antibiotic use and antimicrobial resistance facts.Unity Point Health.Can UTIs go away on their own?
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Microbiology Society.Antibiotics.HealthyChildren.org.The history of antibiotics.Kapoor G, Saigal S, Elongavan A.Action and resistance mechanisms of antibiotics: A guide for clinicians.J Anaesthesiol Clin Pharmacol. September 2017;33(3):300-305. doi:10.4103/joacp.JOACP_349_15.Eyler RF, Shvets K.Clinical pharmacology of antibiotics.CJASN. July 2019; 14(7):1080-1090. doi:10.2215/CJN.08140718.SingleCare.What is levofloxacin and what is it used for?Centers for Disease Control and Prevention.About strep throat.Lyme Disease Association of Southeastern Pennsylvania.Antibiotics.U.S. Food and Drug Administration.Combating antibiotic resistance.MedlinePlus.Antibiotics.Mergenhagen KA, et al.Fact versus fiction: A review of the evidence behind alcohol and antibiotic interactions.Antimicrob Agents Chemother.February 2020;64(3). doi:10.1128/AAC.02167-19.Ramirez J, et al.Antibiotics as major disruptors of gut microbiota.Front Cell Infect Microbiol. September 2020;10:731. doi:10.3389/fcimb.2020.572912.Centers for Disease Control and Prevention.Antibiotic use and antimicrobial resistance facts.Unity Point Health.Can UTIs go away on their own?
Microbiology Society.Antibiotics.
HealthyChildren.org.The history of antibiotics.
Kapoor G, Saigal S, Elongavan A.Action and resistance mechanisms of antibiotics: A guide for clinicians.J Anaesthesiol Clin Pharmacol. September 2017;33(3):300-305. doi:10.4103/joacp.JOACP_349_15.
Eyler RF, Shvets K.Clinical pharmacology of antibiotics.CJASN. July 2019; 14(7):1080-1090. doi:10.2215/CJN.08140718.
SingleCare.What is levofloxacin and what is it used for?
Centers for Disease Control and Prevention.About strep throat.
Lyme Disease Association of Southeastern Pennsylvania.Antibiotics.
U.S. Food and Drug Administration.Combating antibiotic resistance.
MedlinePlus.Antibiotics.
Mergenhagen KA, et al.Fact versus fiction: A review of the evidence behind alcohol and antibiotic interactions.Antimicrob Agents Chemother.February 2020;64(3). doi:10.1128/AAC.02167-19.
Ramirez J, et al.Antibiotics as major disruptors of gut microbiota.Front Cell Infect Microbiol. September 2020;10:731. doi:10.3389/fcimb.2020.572912.
Centers for Disease Control and Prevention.Antibiotic use and antimicrobial resistance facts.
Unity Point Health.Can UTIs go away on their own?
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