Should I use this page, or skip it?
If you have been prescribed antibiotics, or you wonder why a cold did not get any, use this page to take them safely and know when to ask for a review. Skip it and call 999 or go to A&E if a dose is followed by face or throat swelling, trouble breathing, or a spreading blistering rash.
This is a UK medicines guide, not a way to diagnose your own infection or to decide which leftover box in the cupboard to start. Only take antibiotics prescribed for you.
Why won’t I get antibiotics for a cold, flu, or most coughs?
Because those illnesses are usually viral. Antibiotics kill bacteria or stop them multiplying. They do nothing to influenza viruses, cold viruses, or most sore throats. You will still have the same cough — plus a higher chance of diarrhoea, thrush, or a rash.
The NHS no longer uses antibiotics routinely for many chest infections, ear infections in children, or sore throats, because most people recover without them and unnecessary courses speed up resistance. That can feel like being fobbed off. It is usually the opposite: saving a medicine for the day a bacterial infection would actually harm you.
If you are getting worse, you cannot swallow fluids, you are short of breath, you have a very high temperature that will not settle, or you are at higher risk (for example a weakened immune system), that is a reason to be reassessed — not a reason to demand a particular brand.
When are antibiotics the right tool?
They are used for bacterial infections that are unlikely to clear alone, could take too long to settle, might spread to other people, or carry a risk of serious complications. The NHS gives examples such as acne that needs treatment, impetigo, chlamydia, kidney infection, cellulitis and pneumonia. Many mild bacterial infections still get better without antibiotics.
They are also used as a precaution (prophylaxis) around some operations, after some bites or dirty wounds, and for people at high risk of infection — for example after spleen removal, during some chemotherapy, or with sickle cell disease. That decision belongs to the team treating you.
People more vulnerable to infection — including some older adults, people with heart failure, people who take insulin, and people with a weakened immune system — may be offered antibiotics more readily. That is individual clinical judgement, not a rule you can apply from a webpage.
| Situation | Antibiotics usually? | What to do instead or as well |
|---|---|---|
| Cold, flu, most coughs and sore throats | No | Rest, fluids, pharmacy symptom relief; see a GP or 111 if you are getting worse or cannot cope |
| Possible urine, skin, kidney or chest bacterial infection | Sometimes — if a clinician thinks bacteria are likely and treatment will help | Get assessed; do not start leftover tablets from a previous illness |
| After some surgery, bites, or if you are at high risk of infection | Sometimes, as prevention | Follow the team that knows the procedure or your condition |
| Swelling of face or throat, trouble breathing, or a severe spreading rash after a dose | Stop and get emergency help | Call 999 or go to A&E — this can be anaphylaxis |
How should I take them if they are prescribed?
Take them exactly as directed on the packet and in the patient information leaflet. Some need food; some need an empty stomach. They come as tablets, capsules, liquids, creams, drops or, in hospital, injections. The form is chosen for the infection, not for convenience.
If you miss a dose, read the leaflet. Often you take it when you remember unless the next dose is due soon — then skip the missed one. Do not double up. An extra dose is unlikely to be disastrous but makes side effects more likely; more than one extra dose, or feeling very unwell, is an NHS 111 or GP question.
Never share antibiotics or keep them “for the next sore throat”. The dose, the bug, and the safety checks will not match. Tell the prescriber if you are pregnant, breastfeeding, or take other medicines or herbal products.
You may still be infectious after you start. The NHS says that, depending on the infection, it can take between 48 hours and 14 days to stop being infectious. Ask a pharmacist how that applies to you before you go back to work or visit someone vulnerable.
What side effects and allergies should I watch for?
Common effects include feeling sick, being sick, bloating, indigestion and diarrhoea. They are miserable but usually settle. Severe watery diarrhoea, especially with stomach pain or blood, needs medical advice — some antibiotics can allow a gut infection to take hold. A mild rash should be reported before you take the next dose.
Allergic reactions are more often discussed with penicillins and cephalosporins, but any antibiotic can cause one. A mild rash should be reported before the next dose. Call 999 or go to A&E if you get a rash with blistering or peeling, wheeze, tightness in the chest or throat, trouble breathing or talking, or swelling of the mouth, face, lips, tongue or throat.
If you have been labelled penicillin-allergic for years after a childhood rash, mention it — but do not experiment at home. A GP or allergy service may need to sort out whether it was a true allergy.
Can I drink alcohol, and what about the pill?
Go easy on alcohol when you are ill. For most common antibiotics, moderate drinking is unlikely to cause a dangerous interaction, though it can worsen dizziness or nausea. Metronidazole and tinidazole are a hard no — alcohol with those can cause flushing, a racing heartbeat, headache and vomiting. Always check your leaflet.
The NHS advises avoiding alcohol for 48 hours after stopping metronidazole and 72 hours after tinidazole. Linezolid can interact with fermented drinks such as wine and beer. Alcohol can also make doxycycline less suitable in people who drink heavily. When in doubt, the leaflet wins over a general article.
Most antibiotics do not stop the combined pill working. Rifampicin and rifabutin do, and extra contraception is often needed. Vomiting or severe diarrhoea can stop the pill being absorbed, whatever the antibiotic. Ask a pharmacist the same day rather than waiting to see if a period arrives. Find a GPhC-registered pharmacy on Pick My Pharmacy.
Why does “only when needed” matter for everyone else?
Each unnecessary course gives bacteria more practice at surviving. Resistant infections are harder to treat, may need stronger hospital antibiotics, and can spread. This is not a lecture about being a good patient — it is why a GP might offer a delayed prescription (“only start these if you are no better in a few days”) or no prescription at all.
GOV.UK and the NHS treat antimicrobial resistance as a national problem, not a personal failing. Using antibiotics well — the right drug, the right person, the right time — is how they remain useful for urine infections, sepsis, and surgery.
If symptoms get worse on treatment, or are no better in the timeframe you were given, contact the prescriber or NHS 111. That may mean a different diagnosis, a different antibiotic, or an infection that needs to be seen in person.
Keep the patient information leaflet until the course is finished. It is the document that matches your antibiotic — including whether it clashes with other medicines — rather than a general article or a group chat.
When is this page NOT the right thing to read?
Skip this page if you are having a serious allergic reaction, if a child is struggling to breathe or is floppy and unresponsive, or if you think you have sepsis (severe breathlessness, confusion, mottled skin, not passing urine). Those are 999 problems.
It is also the wrong page if you need infection-specific advice — a UTI, tonsillitis, sinusitis, pneumonia or cellulitis each has its own red flags. Do not use this article to choose an antibiotic or a dose. Follow the prescription in your name and the leaflet in the box.
Common questions about antibiotics
- Why won't my doctor give me antibiotics for a cold?
- Colds, flu and most coughs and sore throats are caused by viruses, which antibiotics cannot treat. Taking antibiotics when they will not help can cause side effects and contributes to antibiotic resistance, so they are prescribed only when a bacterial infection is likely.
- What is antibiotic resistance?
- Antibiotic resistance is when bacteria change so that antibiotics no longer kill them or stop them spreading. Using antibiotics when you do not need them makes this more likely, which can mean they will not work for you — or for someone else — in the future.
- Should I finish the whole course?
- Take antibiotics exactly as prescribed. Follow the packet, the patient information leaflet, and what your GP or pharmacist told you. Do not stop early to "save some for next time", and do not share leftover tablets. If you are unsure, ask a pharmacist rather than guessing.
- Can I drink alcohol with antibiotics?
- With most common antibiotics, moderate alcohol is unlikely to cause a serious interaction, though it can worsen side effects such as sickness or dizziness. You must avoid alcohol completely with metronidazole and tinidazole, and for a short time after the last dose. Always check your leaflet.
- Do antibiotics stop the contraceptive pill working?
- Most antibiotics do not. The important exceptions are rifampicin and rifabutin, which can reduce how well the combined pill works — extra contraception such as condoms may be needed. If you have vomiting or severe diarrhoea on any antibiotic, the pill may not be absorbed properly; ask a pharmacist.
- What if I miss a dose?
- Check the leaflet first. In many cases you take the missed dose when you remember, then continue as normal, unless it is nearly time for the next one — then skip the missed dose. Do not take a double dose. If you have taken extra doses and feel unwell, call NHS 111.
- When are antibiotics actually needed?
- When a bacterial infection is unlikely to clear on its own, could spread, might cause serious complications, or would take too long to settle. Examples include some urine, skin, kidney and chest infections, and some sexually transmitted infections. Many mild bacterial infections still get better without them.
- I am allergic to penicillin — what happens?
- Tell every prescriber and pharmacist, and check hospital records are up to date. Many people labelled "penicillin allergic" are not truly allergic; a clinician may explore that carefully. Never take a penicillin-type antibiotic if you have had a serious reaction. Call 999 for swelling of the face or throat, wheeze, or trouble breathing.