For many years antibiotics have been used to eradicate different bacterial infections. However, misuse or prolonged use, as well as inadequate dosage have created multiple pathogenic bacterial resistances in the human body.
These harmful bacterial resistances can alter the existing relationship between the organism that in this case would be the host and the intestinal microbiota, resulting in a dysregulation of the individual’s immune system and triggering different diseases.
Antibiotics have the specialty of attacking the genes of microorganisms and producing their elimination, that is, they can also easily attack beneficial microorganisms through their genes since these drugs do not differentiate between healthy and harmful bacteria, unless you have a strengthened immune system.
In the case of the bacterium Clostridium Difficile is associated with causing diarrhea in both children and adults due to the use of antibiotics, so it is important to include probiotic strains. 
Fermented milk from kefir significantly shortens the duration of antibiotic-associated diarrhea and improves gastrointestinal discomfort. 
There are scientific clinical trials where he relates the antimicrobial effect of kefir with the bacterium Helicobacter Pylori (which causes diarrhea) giving significant results in terms of reducing the activity of this bacterium.  
This means that kefir is more than a simple probiotic where not only is involved its ability to improve annoying effects that antibiotics leave in their wake, but we can also take advantage of this type of mechanism in harmful bacteria without having to compromise the good microorganisms of the intestinal flora.
With this in mind, we clearly see that the joint treatment of antibiotics with milk kefir has been used in scientific studies with positive results, so at the moment, there is no contraindication in its use in this aspect.
The relationship between milk kefir and its effect on antibiotic use is described in more detail below.
Is it necessary to consume milk kefir when undergoing treatment?
Most antibiotics usually create stable alterations, which can be lasting in the intestinal microbiota because their main function is to exert the bactericidal effect, that is, to eliminate the bacteria to end the infection, of course it also compromises healthy bacteria, then It is necessary that during treatment with these types of drugs healthy probiotic strains are included to restore what the antibiotic is eradicating during its consumption.
As previously explained, during antibiotic treatment opportunistic bacteria can be activated causing gastrointestinal symptoms such as diarrhea and gastroenteritis, the main microorganisms of kefir such as Bifidobacterium, Lactobacillus and their species have the ability to improve these symptoms during or after antibiotic treatment.  
In addition, the bacteria Saccharomyces and Streptococci together with the other bacteria mentioned in kefir help regulate the intestinal microbiota, to prevent subsequent sequelae after the duration of the treatment has ended.
Lactobacillus Kefiranofaciens is a bacterium found in kefir granules and has antimicrobial and anti-inflammatory effect, where there are scientific publications that have tested these effects of kefir in animal studies in vivo and have given favorable results.
This means that there may be the possibility of maximizing the bactericidal effect of the antibiotic thanks to the antimicrobial effect of milk kefir, however, studies tested in humans are needed to prove this synergy between both products.
For the same reason if there is such a possibility mentioned above, it will be necessary to consume milk kefir during antibiotic treatment at different time intervals to prevent the antibiotic from removing the probiotics from kefir immediately in order to maximize its bactericidal effect while reducing side effects.
In the end, what we want to achieve is its effect of regulating and improving the healthy microbiota to prevent the sequelae of the antibiotic or even reduce it.
Can infants consume kefir with antibiotics during treatment?
The use of antibiotics is common in children since children are the most likely to get sick because their immune system continues to develop to strengthen until adulthood.
There are retrospective publications on the use of probiotics for the prevention of diarrhea associated with the use of antibiotics giving as moderate-quality evidence on their protective effect. 
And although milk kefir is a complex probiotic, there are few studies that support the consumption of this specific product during childhood.
Additionally it is important to bear in mind that milk kefir, due to the presence of yeast, may contain 0.5% to 3% alcohol product of fermentation, so its consumption is discouraged in lactating babies and infants, however, they can consume it from 6 months onwards when solids are already included in the diet.
In the case of adolescents there are also studies showing that the administration of probiotics in young and middle-aged people can be useful to prevent especially diarrhea associated with the antibiotic, while in older people there were no benefits evidenced during the trial, although this does not mean that there is no possibility that older people can obtain the benefits of consuming kefir. 
These studies are clinically tested with different microbial strains in general but specifically kefir there is little evidence that really confirms whether this drink can be consumed even in adolescents.
Therefore, the consumption of milk kefir in infants when it is in a treatment with antibiotics is possible, you should only be aware that the alcohol content of kefir is not high, the latter being the only thing that really makes its use discouraged, although scientific evidence does not favor its use.
In fact, there is a study that effectively analyzed this effect in children aged 1 to 5 years where it is concluded that the administration for 14 days of milk kefir did NOT help prevent diarrhea associated with the use of antibiotics. 
How do probiotics in milk kefir work to prevent sequelae during antibiotic treatment?
To avoid the sequelae that are left by the use of antibiotics or even after having completed the treatment, probiotics can activate different defensive barrier mechanisms in the intestinal mucosa to prevent or improve the side effects that these medications leave, but that must be accompanied by other healthy habits, that is, that a single effect of kefir is not enough. but several fundamental acts for the organism to reestablish its normal bacterial flora.
Probiotic strains of kefir could reduce the binding of harmful microorganisms to the intestinal mucosa and opportunistic microbial overgrowth, which corresponds to kefir’s renowned antimicrobial capacity.
Another mechanism would be as immunomodulatory effect, increasing intestinal pH and producing immunoglobulins to strengthen the immune system.
For its part, the short-chain fatty acids contained in kefir are useful to improve the absorption of nutrients and produce energy for the microbiota of the intestinal flora and all these acts of the bacteria of the kefir granules make it more tolerable to treatment to avoid the side effects of antibiotics.  
There are studies that relate the intestinal microbiota and bifidobacteria in the ability to directly positively influence immune cells by sharing their genes with those of the intestinal microbiota. 
Most clinical trials have been conducted with the following probiotic bacteria individually to study their effects on the intestinal microbiota: Saccharomyces, Lactobacillus and Bifidobacterium, and although all these microorganisms mentioned help to restore the intestinal microbiota in general, each bacterial strain has its own pathway or mechanism in favorably influencing the cells of the immune system.
It is now known that in the granules of milk kefir we can find these three bacteria mentioned above, among other species. Then it could be deduced that kefir contains sufficient mechanisms to prevent sequelae during treatment with antibiotics, but we are waiting for scientific evidence that can support this hypothesis.
Can milk kefir be consumed in conjunction with antibiotics?
There are series of clinical studies that show that the consumption of probiotics in conjunction with antibiotics reduces the risk of causing diarrhea associated with these drugs, however, it is still not entirely clear in health professionals, more human trials would have to be carried out to be certain, for the same reason it may happen that within the health system they do not indicate it for lack of more studies in people. 
In conclusion, to the above, it would not be ideal to consume milk kefir at the same time with antibiotics because there is no support that really endorses or explains if there is benefit in doing it together and the publications that already exist are few.
What I do recommend is to do it at different times, kefir is a drink-type food then you can include it in your daily diet planning the space of time between the antibiotic and this probiotic, in general most antibiotics have a separation time between one taking and the other, it is usually 7 to 8 hours approximately, Kefir could be consumed between main meals or as an appetizer.
A scientific study mentions the importance of consuming probiotics during the 72 hours after the start of antibiotic therapy to achieve the preventive effect of diarrhea produced by it. 
This publication can guide us as a starting point to start consuming the drink after the intake of the antibiotic.
Another case is in gastritis, milk kefir can inhibit in its antimicrobial effect the bacterium Helicobacter pylori, if taken in conjunction with antibiotics can enhance the bactericidal effect of both products and in turn exerting protective effect of the intestinal mucosa by milk kefir.  
You can see more about this by clicking on the link in our article on kefir consumption and its effect on gastritis.
What would be the recommended dose to consume milk kefir during antibiotic intake?
There are few studies on the useful dose of probiotics for different infections, and it will also depend on age groups, the dose can vary between infants, adults, and older people.
Most health professionals indicate the amount of probiotic consumption in the presentation of tablets or capsules and powders, since the probiotic microorganisms are encapsulated, but the disadvantage is the price of it, in addition to the fact that within the same industry there are companies that do not really ensure the quality of bacterial strains.
Unlike artisanal probiotic foods, its indication as to the recommended dose may vary according to the few scientific publications that have been made, however, general recommendations indicate that it should be incorporated gradually, from 180ml to even 500ml of kefir.
While the presentations in capsules or tablets or vials have different indications in terms of their dose, health professionals generally indicate it through formulas called bacterial colony forming units. 
As for the time of its consumption, it is supported by the following study where it mentions that with a duration of 1 to 3 weeks more than the duration of antibiotic treatment, the desired benefits are obtained. 
Can the antibiotic be replaced by milk kefir?
You cannot replace the antibiotic by milk kefir nor by any probiotic, based on the fact that at this time there is no scientific evidence to support the replacement of the antibiotic by milk kefir, what can be done is to use it as a complement during treatment with antibiotic therapy.
Most scientific journals support the use of probiotics as an alternative to improve or prevent symptoms as we have already explained above, being a valuable complement to antibiotics in enhancing their bactericidal effect and their effect and replenish healthy bacteria of the intestinal flora.   
Now what we can do is maximize the effects of the probiotic during antimicrobial therapy with antibiotics, and it is through a good diet that includes vegetables such as artichoke, onion, asparagus, carrots that generally act as prebiotic foods and help enhance the benefits of microorganisms.
As for kefir milk, it has no effect on reducing the action of antibiotics, and if you are allergic or intolerant to dairy products, you can replace it with a water-based kefir and add sugar as a glucose substrate for fermentation which is what kefir milk does.
In conclusion, try to use milk kefir in those windows where you are not ingesting the antibiotic, as this could eventually prevent the appearance of side effects such as diarrhea, but it will also benefit you to repopulate your microbiota with probiotic bacterial strains. 
Dear reader, we have reached the end of our article, we hope that this journey has been to your liking, hoping that it continues with the interesting publications that we will leave exclusively for you.