Antibiotics are among the most important medicines in modern healthcare. When they are truly needed, they can treat bacterial infections, prevent serious complications, and save lives.
But antibiotics are not suitable for every infection. They do not treat viruses such as the common cold or influenza, and taking an antibiotic unnecessarily can still cause side effects. Incorrect or unnecessary use also contributes to antimicrobial resistance (AMR), making some bacterial infections increasingly difficult to treat.
The World Health Organization reported in July 2026 that approximately one in six laboratory-confirmed bacterial infections worldwide in 2023 were resistant to antibiotic treatment. Using antibiotics correctly therefore matters for two reasons: it gives you the best chance of treating your current infection safely, and it helps preserve the effectiveness of antibiotics for the future.
| Quick takeaway Use antibiotics only when they are needed, take them exactly as prescribed, check medicine-specific food and interaction instructions, and never share or save prescription antibiotics for another illness. |
The 7 Most Important Rules for Taking Antibiotics
- Take antibiotics only when they have been prescribed or recommended for an infection that needs them.
- Take the correct antibiotic, dose, and duration exactly as instructed.
- Follow the timing instructions on the label and try to take each dose consistently.
- Check whether your antibiotic should be taken with food, on an empty stomach, or separated from other medicines or supplements.
- Never double a dose unless a healthcare professional specifically tells you to do so.
- Know the common side effects and the warning signs that require medical attention.
- Do not share antibiotics, use someone else’s prescription, or save leftovers to treat a future illness.
When Do Antibiotics Actually Help?
Antibiotics work against bacteria, not viruses. However, even some bacterial infections can improve without antibiotics, so the decision depends on the infection, its severity, your health, and clinical assessment.
| Antibiotics may be needed | Antibiotics are usually not helpful |
| Confirmed strep throat | Common cold |
| Some urinary tract infections | Influenza |
| Bacterial pneumonia | Most uncomplicated acute bronchitis |
| Cellulitis and selected bacterial skin infections | Most viral sore throats |
| Serious bloodstream infections | Viral runny nose, even when mucus is yellow or green |
| Selected bacterial ear or sinus infections | Many mild early ear or sinus infections |
A healthcare professional may sometimes recommend watchful waiting or a delayed prescription, particularly for illnesses that often improve without immediate antibiotic treatment. This does not mean an infection is being ignored; it means antibiotics are being reserved for situations in which their expected benefit outweighs their potential harm.
Before Taking the First Dose
When an antibiotic is prescribed, make sure you understand what you are taking and why. You should know the infection being treated, the name of the antibiotic, the dose, how often to take it, how many days it should be taken, whether there are special food or drink instructions, and which side effects require medical attention.
Tell the doctor, dentist, nurse practitioner, or pharmacist about any drug allergies and about other medicines, vitamins, herbal remedies, or supplements you use. This is particularly important if you are pregnant or breastfeeding, have kidney or liver disease, take anticoagulants such as warfarin, take medicines for epilepsy, or previously experienced a serious reaction to an antibiotic.
Take the Dose Exactly as Directed
The correct dose and timing depend on the antibiotic and the infection being treated. Some antibiotics are taken once daily, while others may need several doses during the day. Follow the prescription label rather than copying another person’s antibiotic schedule or relying on instructions from a previous infection.
Try to take doses at approximately the recommended intervals. Phone reminders, medication apps, or a simple daily schedule can help if several doses are required. Never increase the dose because you think the infection is severe. Taking more antibiotic than prescribed does not necessarily make treatment work faster and may increase harmful effects.
Should Antibiotics Be Taken With Food?
There is no single rule that applies to every antibiotic. Some can be taken with or without food, some are easier on the stomach when taken with a meal, and others have specific instructions about dairy products, minerals, or antacids.
For example, ciprofloxacin tablets or liquid should not be taken at the same time as dairy products alone or calcium-fortified drinks because absorption can be reduced. Iron, calcium, zinc, and some antacids can also interfere with ciprofloxacin and require dose separation. Doxycycline can interact with antacids and supplements containing iron or zinc.
The safest approach is simple: read the pharmacy label and patient information leaflet for your particular antibiotic, and ask a pharmacist if anything is unclear.
Take Tablets and Capsules With Enough Water
Unless your medicine has different instructions, swallowing tablets or capsules with water is generally appropriate. Some medicines need extra care. Doxycycline should be swallowed with a full glass of water while sitting or standing, and you should avoid lying down for at least 30 minutes afterwards because this helps reduce irritation of the throat or oesophagus.
What Should You Do If You Miss a Dose?
If you forget a dose, check the medicine leaflet first. For many antibiotics, the usual advice is to take the forgotten dose when you remember unless it is nearly time for the next scheduled dose. If the next dose is close, skip the missed dose and resume the normal schedule.
| Do not double up Do not take two doses together simply to compensate for a missed dose unless a healthcare professional specifically instructs you to do so. If you are uncertain, contact a pharmacist or your prescriber. |
Should You Stop Antibiotics When You Feel Better?
Do not shorten, extend, or otherwise change the treatment duration on your own. Modern antibiotic prescribing increasingly aims to use the shortest effective duration for a particular infection, and some infections now require shorter courses than were traditionally prescribed.
The correct duration still depends on the infection, the antibiotic, your response to treatment, and individual risk factors. Feeling better does not automatically tell you whether treatment has been adequate, while taking antibiotics longer than necessary can add avoidable exposure. Take the antibiotic for the duration currently prescribed unless the clinician treating you advises you to change or stop it.
Can You Drink Alcohol While Taking Antibiotics?
Alcohol advice is more specific than the common statement that alcohol must be avoided with every antibiotic. Alcohol does not cause a major direct interaction with many commonly used antibiotics, although drinking while you are unwell may worsen nausea, dizziness, dehydration, or other symptoms.
- Metronidazole: Avoid alcohol during treatment and for at least 48 hours after the final dose.
- Tinidazole: Avoid alcohol during treatment and for at least 72 hours after the final dose.
- Other situations: Linezolid can interact with some fermented alcoholic drinks, and alcohol can affect doxycycline, particularly in people with a history of heavy drinking.
Antibiotics Can Interact With Other Medicines
Interactions do not occur with every antibiotic, but they can sometimes be clinically important. Antacids and supplements containing calcium, magnesium, iron, or zinc may reduce absorption of certain antibiotics. Some antibiotics can also interact with anticoagulants, anti-seizure medicines, methotrexate, and other prescription drugs.
Rifampicin and rifabutin can reduce the effectiveness of some hormonal contraceptives. Most commonly used antibiotics do not have this direct effect, although vomiting or severe diarrhoea can affect absorption of oral contraceptive pills. This is why your clinician or pharmacist should know about all prescription medicines, over-the-counter medicines, supplements, and herbal products you use.
Common Side Effects and Warning Signs
Most people take antibiotics without serious problems, but side effects vary between medicines. Common effects include nausea, diarrhoea, stomach discomfort, dizziness, rash, and thrush or yeast infection.
| More common effects | Seek urgent medical help for |
|---|---|
| Nausea or stomach upset | Difficulty breathing |
| Mild diarrhoea | Swelling of the lips, face, tongue, or throat |
| Dizziness with some antibiotics | A rapidly spreading, blistering, peeling, or severe rash |
| Thrush or yeast infection | Severe or persistent watery or bloody diarrhoea |
| Mild rash with some medicines | Fainting or other symptoms of a severe allergic reaction |
Antibiotics can disturb normal bacteria in the intestine and allow Clostridioides difficile (C. diff) to multiply. C. diff can cause significant diarrhoea and inflammation of the colon, and most cases occur while taking antibiotics or soon afterwards. Contact a healthcare professional if you develop diarrhoea during or after antibiotic treatment, especially if it is severe or persistent, or you also have abdominal pain, fever, blood in the stool, or signs of dehydration.
Extra Caution With Fluoroquinolone Antibiotics
Fluoroquinolones such as ciprofloxacin have important potential adverse effects and are generally reserved for situations in which they are considered appropriate. Rare but potentially serious problems can affect tendons, muscles, joints, nerves, and the central nervous system.
If you develop significant tendon pain or swelling, unusual numbness or tingling, marked muscle weakness, or unexpected neurological or mental symptoms while taking a fluoroquinolone, seek medical advice promptly.
Penicillin Allergy: Is the Label Correct?
Many people have been told at some point that they are allergic to penicillin. Sometimes the label comes from a childhood rash, gastrointestinal upset, a family history of allergy, or a reaction that was never clearly investigated.
According to the U.S. Centers for Disease Control and Prevention, about 10% of U.S. patients report a penicillin allergy, but fewer than 1% are found to be truly allergic when appropriately evaluated. An incorrect allergy label can limit treatment choices and sometimes leads to broader-spectrum antibiotics.
Do not test a suspected allergy yourself. If the history is uncertain, ask a healthcare professional whether formal allergy assessment is appropriate. A previous severe reaction such as anaphylaxis or a serious blistering skin reaction must always be taken seriously.
Four Common Antibiotics: Practical Points
| Antibiotic | Important practical advice |
| Amoxicillin | Follow the prescribed schedule. It can generally be taken before or after food. Tell your clinician about any history of penicillin allergy. |
| Doxycycline | Swallow with plenty of water while sitting or standing. Do not lie down for at least 30 minutes. Check interactions with antacids, iron, zinc, and other supplements. |
| Metronidazole | Follow the label and take with or after food if this is advised or if it helps stomach upset. Avoid alcohol during treatment and for at least 48 hours afterwards. |
| Ciprofloxacin | Take exactly as prescribed. Check instructions regarding dairy products, calcium-fortified drinks, antacids, and mineral supplements. Report significant tendon, nerve, muscle, or neurological symptoms promptly. |
These are general points only and do not replace the instructions supplied with your own prescription.
Pregnancy, Breastfeeding, Kidney Disease, and Liver Disease
Antibiotics are not interchangeable. Some are commonly used during pregnancy while others are avoided or reserved for specific circumstances, and similar considerations apply during breastfeeding. Kidney function is also important because several antibiotics are removed through the kidneys and may require dose adjustment when kidney function is reduced. People with significant liver disease may need different drug choices or monitoring.
If you are pregnant, planning a pregnancy, breastfeeding, have kidney or liver disease, or receive dialysis, make sure the prescriber knows before treatment begins.
Do Not Share or Reuse Leftover Antibiotics
An antibiotic prescribed for one infection may be completely inappropriate for another, even when the symptoms seem similar. Using leftover antibiotics can mean taking the wrong medicine, an inadequate amount, or treatment that masks symptoms and delays the correct diagnosis.
Never share prescription antibiotics with friends or relatives and never take medicine prescribed for another person. Keep medicines in their original packaging and follow storage instructions. Some liquid antibiotics have specific temperature or expiry requirements after preparation.
Unused or expired medicines should preferably be returned through an approved pharmacy or medicine take-back programme where these services are available. Follow local medicine-disposal guidance.
Why Correct Antibiotic Use Matters to Everyone
Antibiotic resistance does not mean that your body becomes resistant to an antibiotic. It means that bacteria change in ways that allow them to survive medicines that previously killed them or stopped their growth.
Whenever antibiotics are used, they create selection pressure on bacteria. Unnecessary or inappropriate use increases opportunities for resistant organisms to be selected and spread. Resistant infections can be harder to treat, may require more complex medicines, and can make medical procedures such as major surgery, cancer treatment, transplantation, and intensive care more difficult.
Responsible use is therefore not simply about finishing a bottle of tablets. It means using an antibiotic only when appropriate, selecting the right drug, taking the right dose, and using it for the right duration.
Frequently Asked Questions
Can antibiotics treat a cold or flu?
No. Colds and influenza are caused by viruses, and antibiotics do not kill viruses. Antibiotics may occasionally be required if a separate bacterial complication develops, but that requires clinical assessment.
Does yellow or green mucus mean I need antibiotics?
Not necessarily. Mucus can change colour during viral respiratory infections. Colour alone does not prove that an infection is bacterial.
Can I stop an antibiotic as soon as I feel better?
Do not alter the prescribed duration yourself. If you are improving quickly or experiencing adverse effects, ask the treating clinician whether your treatment plan should be reviewed.
Should I take two tablets if I forget one?
Usually not. For many antibiotics, a missed dose is taken when remembered unless the next dose is approaching. Check the medicine leaflet or ask a pharmacist because instructions can differ.
Do all antibiotics interfere with birth-control pills?
No. Most commonly used antibiotics do not directly reduce the effectiveness of hormonal contraception. Rifampicin and rifabutin are important exceptions. Vomiting or severe diarrhoea can also reduce absorption of oral contraceptive pills.
Can I drink alcohol?
It depends on the antibiotic. Alcohol does not have a major direct interaction with many common antibiotics, but it can worsen side effects. Avoid alcohol completely with metronidazole and tinidazole during treatment and for the recommended period afterwards.
What if the antibiotic does not seem to be working?
Do not increase the dose yourself. Contact your clinician if symptoms are worsening, new concerning symptoms develop, or you are not improving within the timeframe you were told to expect.
The Bottom Line
Antibiotics are powerful medicines, but their benefits depend on using them correctly. Take them only when they are genuinely indicated, follow the dose, timing, food instructions, and treatment duration supplied with your prescription, check for interactions, and seek help if serious side effects develop. Never share antibiotics or save prescription antibiotics for another illness.
Used wisely, antibiotics can continue to save lives. Used unnecessarily or incorrectly, they can cause avoidable harm and accelerate antimicrobial resistance.
Important Medical Disclaimer
| General information only This article provides general health information and is not intended to diagnose an infection, recommend a specific antibiotic, or replace advice from a qualified healthcare professional. Antibiotic selection, dose, timing, and duration should be individualized according to the infection and the patient’s medical circumstances. |
Authoritative Sources and Further Reading
1. World Health Organization. Antimicrobial resistance fact sheet, 16 July 2026. Source
2. World Health Organization. Global antibiotic resistance surveillance report 2025. Source
3. CDC. Healthy Habits: Antibiotic Do’s and Don’ts, updated September 2025. Source
4. CDC. Clinical Features of Penicillin Allergy, updated August 2025. Source
5. CDC. About C. diff, updated May 2026. Source
6. NHS. Antibiotics: overview and missed-dose advice. Source
7. NHS. Antibiotics: interactions, alcohol, and contraception. Source
8. NHS. Doxycycline: how to take it and key interactions. Source
9. NHS. Ciprofloxacin: food, supplement, and medicine interactions. Source
10. NHS. Amoxicillin: how and when to take it. Source 11. U.S. Food and Drug Administration. Fluoroquinolone antibiotic safety communication. Source