Medically reviewed guide · Last updated: 23 June 2026 · Reading time: approx. 13 min

Antibiotic resistance: why correct use matters

Antibiotics belong to the most important discoveries of medicine: they fight bacteria and can heal life-threatening infections against which there was earlier no remedy. Yet through excessive and improper use more and more bacteria become insensitive to antibiotics. Resistant pathogens today belong to the greatest challenges for global health. The good news: each individual can with the correct intake contribute to slowing resistances down. This makes the topic not a pure expert question but something that affects everyone in everyday life. This guide explains understandably how resistances arise, what you should observe with the intake, why no leftovers should remain and which widespread myths are wrong. Important beforehand: this guide does not replace medical advice and deliberately contains no dosage details. Antibiotics are prescription only and belong in medical hands. Anyone who understands the most important connections can handle these medicines more consciously in everyday life and thus actively contributes to preserving their effectiveness.

What antibiotic resistance is and how it arises

Resistance means opposition. One speaks of antibiotic resistance when bacteria become insensitive to an antibiotic and the agent no longer works. Bacteria are adaptable organisms that react to threats, and exactly this adaptability makes them a challenge in dealing with antibiotics. The bacteria have then acquired a property that protects them, for example by forming a substance that makes the antibiotic ineffective. If pathogens are insensitive to several antibiotics at the same time, one speaks of multidrug-resistant pathogens. Known examples are certain staphylococci such as MRSA, but also strains of Escherichia coli or klebsiella. Infections with such pathogens are harder to treat and can take a more complicated course. Especially at risk are people with a weakened immune system, older persons and children with still immature defences, with whom a hard-to-treat infection can have serious consequences.

Decisive is how resistances arise. Every use of antibiotics exerts a pressure on the bacteria: the sensitive pathogens die off, while individual resistant ones survive and can continue to multiply undisturbed. This process is called selection, because the antibiotic unintentionally selects exactly the pathogens that withstand it. This is made possible through random changes in the genetic material, which let new protective mechanisms arise. These properties bacteria can even pass on among themselves, also across species boundaries. Unlike often assumed, it is not the person who becomes resistant to the antibiotic but the bacteria, that is an important difference for understanding the problem. The more frequently and improperly antibiotics are used, the faster resistant pathogens spread. The arising of resistances can therefore not be completely prevented but clearly slowed down through a careful handling. Exactly for this reason it is no abstract problem of distant clinics but one that is connected with the behaviour of each individual patient.

Correct intake: what really matters

So that an antibiotic can work optimally, it must be used correctly. Even small mistakes with the intake can impair the effect or unnecessarily promote resistances, therefore it is worthwhile to know the most important points. Most important is the intake duration: antibiotics should be taken exactly as long as was medically prescribed. Earlier it applied across the board to always use up the whole pack. This old rule of thumb is outdated today, because an unnecessarily long intake can itself contribute to resistance formation. Today one knows that the right therapy duration depends on the individual case and is determined medically, sometimes it is shorter than earlier assumed. But do not end the intake on your own earlier just because the complaints subside, because then pathogens could still be left that trigger a relapse. If you have the impression that the therapy is set too long or too short, the right reaction is the consultation with the medical practice, not the own decision about continuation or discontinuation.

Equally important is the regular intake at fixed intervals, so that the active ingredient level in the body stays as even as possible. If an agent is to be taken for example every eight hours, fixed times help as a memory aid. An even distribution over the day ensures that the active ingredient is continuously present in sufficient amount and the bacteria do not get the opportunity in between to multiply again. Antibiotics are as a rule taken with a glass of water, not with milk or milk products, since the contained calcium can hinder the uptake of some active ingredients. Interactions with other medicines too are possible, for example with blood thinners or the contraceptive pill. What applies in the individual case is in the package leaflet, and in case of doubt an inquiry in the pharmacy helps. Anyone who takes several medicines at the same time should inform the medical practice about it, since effects can mutually intensify or weaken and some combinations require a time interval.

No leftovers: storing and disposing

An often underestimated point is the handling of leftover antibiotics. They should neither be kept for a later own use nor passed on to other people. The reason: every antibiotic intake belongs medically accompanied, because the fitting agent depends on pathogen, disease and person. What helped with one infection can be ineffective or even harmful with the next. An antibiotic that works against a certain type of bacteria is possibly completely useless against another, and without a medical diagnosis this cannot be assessed. A self-treatment with leftovers from the drawer promotes resistances and can delay a necessary, targeted treatment. Ideally no leftovers remain at all, if the pack size fits the prescribed therapy. In some cases it can be clarified already when filling the prescription at the pharmacy whether the dispensed amount fits exactly the prescribed duration, so that as little as possible remains at the end.

If tablets do remain, the correct disposal is important. In Germany medicine leftovers can as a rule be disposed of via the normal residual waste, since this is incinerated. Important is only to pack the leftovers in such a way that children or pets do not accidentally get to them, for example by leaving the tablets in the original packaging. Some pharmacies also take back old medicines but are not obliged to. Under no circumstances do antibiotics belong in the drain or the toilet: via the waste water the active ingredients get into the environment, burden waters and additionally contribute to the arising of resistances. Treatment plants can filter out many of these substances only incompletely, which is why residues demonstrably end up in rivers and lakes. In case of doubt the pharmacy is the right point of contact for questions about disposal, since regional regulations can deviate. In some cities and districts there are own collection points or hazardous-waste mobiles for old medicines, about the local options the pharmacy or the municipal waste advice informs.

What you can do yourself

Resistances arise not only in clinics or agriculture but are also co-determined by the behaviour of each individual. That may at first surprise, yet in the sum of many treatments the behaviour of the patients co-decides how fast resistances spread. The most important thing is to take antibiotics only after medical prescription and exactly according to instruction. To this belongs keeping the prescribed duration, taking the agents regularly and not keeping or passing on leftovers. Already these simple basic rules make a noticeable difference when they are consistently observed by many people. It also helps not to push for an antibiotic in the medical practice when it is not necessary. Preventively, hygiene such as thorough hand washing and recommended vaccinations lower the number of infections and with it the need for antibiotics. Every avoided infection is an infection that does not have to be treated at all, and exactly here lies the greatest lever that each individual holds in their hand.

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In sum it applies: antibiotics are valuable medicines whose effectiveness we must protect together. The most important levers lie in the correct intake, the doing-without of unnecessary use and the correct handling of leftovers. Active ingredients such as amoxicillin and azithromycin help reliably when they are used in a targeted and correct way. Whether an antibiotic is necessary and which one is always decided by the medical practice. This way a global problem remains an area in which your own behaviour makes a real difference. Anyone who takes antibiotics seriously, uses them only when needed and exactly according to specification and disposes of leftovers correctly, protects not only their own health but helps ensure that these important medicines also work in the future.