Many common infections are caused by germs called viruses. Antibiotic medicines do not kill viruses. Also, many infections caused by germs called bacteria do not need antibiotics. These infections often get better without antibiotic treatment. Excessive use of antibiotics may allow the germs to become resistant to the antibiotic medicines, so that they will not work when they really are needed. They may also sometimes cause side-effects.
This is why antibiotics are not prescribed for many infections.
Many common infections of the nose, throat, sinuses, ears and chest are caused by germs called viruses. Flu-like illnesses are also caused by viruses. Diarrhoea and/or being sick (vomiting) are often due to a viral infection of the gut. If you are normally well, your defence (immune) system is good at fighting off many types of viral infection. An antibiotic medicine is not needed if a virus is causing an infection. This is because:
- Antibiotics do not kill viruses. Antibiotics only kill germs called bacteria.
- Antibiotics may cause side-effects such as diarrhoea, rashes, feeling sick, etc.
- Overuse of antibiotics when they have not been necessary has led to some bacteria becoming resistant to them. This means that some antibiotics will not work when they are really needed.
See the separate leaflet called Treating Your Infection (Public Health England).
You may feel unwell for several days or more until a viral infection clears. Treatment aims to ease symptoms. Treatments that are commonly advised for viral infections include the following:
- Paracetamol or ibuprofen to reduce a high temperature (fever) and to ease aches, pains and headaches.
- Making sure you drink enough to prevent mild loss of water from the body (dehydration). Dehydration may develop if you have a high temperature and it can make a headache and tiredness much worse.
- Do not wrap up, but try to cool down if you have a high temperature. This is particularly important in children. If a child has a high temperature then take their clothes off (in a warm, but not hot, room) and consider giving some paracetamol or ibuprofen.
- Other advice may be given for specific symptoms. For example, decongestants for a blocked nose, etc. Ask a pharmacist for advice.
What about bacterial infections?
The immune system can clear most infections caused by germs called bacteria. For example, antibiotic medicines usually do little to speed up recovery of bronchitis, or most ear, nose and throat infections that are caused by bacteria. However, you do need antibiotics if you have certain serious infections caused by bacteria, such as meningitis or pneumonia. When you are ill, doctors are skilled at checking you over to rule out serious illness and to advise if an antibiotic is needed.
If evidence and guidelines suggest that an infection will get better without an antibiotic, it is best not to use one unnecessarily. Excessive use of antibiotics results in the bacteria becoming used to them and adapting. If this happens, bacteria have become "resistant", which means the antibiotic no longer works against them. When this happens it means that doctors may have no useful treatment for infections which are serious and life-threatening
What if symptoms change?
Occasionally, mild infections caused by germs (viral or bacterial) develop into more serious infections. See a doctor to review the situation if the illness appears to change, becomes worse, does not go after a few days, or if you are worried about any new symptom that develops. If your illness has worsened, or if you have developed complications, it may be that you now do need an antibiotic. If this is the case, your doctor will prescribe an antibiotic if it is needed.
Occasionally you may be given a "back-up" prescription for an antibiotic to take if your condition gets worse. If this is the case, your doctor will give you instructions so you know in what situation you should start taking the medication. If you are not sure, call or see your doctor for advice.
Further reading & references
- Antimicrobial stewardship: systems and processes for effective antimicrobial medicine use; NICE Guidelines (August 2015)
- Antibiotic awareness resources: key messages on antibiotic use; Public Health England (PHE)
- Respiratory tract infections – antibiotic prescribing: Prescribing of antibiotics for self-limiting respiratory tract infections in adults and children in primary care; NICE Clinical Guideline (July 2008)
- Antimicrobial resistance. World Health Organization (WHO); Fact Sheet, April 2015
- Antimicrobial Resistance; European Centre for Disease Prevention and Control
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.
Dr Tim Kenny
Dr Mary Harding
Prof Cathy Jackson