Antibiotics

Antibiotics are used to treat or prevent some types of bacterial infection. They kill bacteria or prevent them from reproducing and spreading.

Antibiotics aren't effective against viral infections. This includes the common cold, flu, most coughs and sore throats.

Antibiotics aren't routinely prescribed for mild bacterial infections. This is because the immune system can usually clear these on it's own.

When are antibiotics used?

Antibiotics may be used to treat bacterial infections that:

• are unlikely to clear up without antibiotics
• could infect others unless treated
• could take too long to clear without treatment
• carry a risk of more serious complications

Antibiotics to prevent infection

Antibiotics are sometimes given as a precaution to prevent an infection. This is known as antibiotic prophylaxis.

Surgery

Antibiotic prophylaxis is normally recommended if you're having surgery in a certain area. This is because there could be a higher risk of infection.

Your surgical team will be able to tell you if you need antibiotic prophylaxis.

People vulnerable to infection

Antibiotics may be recommended for people who are more vulnerable to infection. This includes:

• people aged over 75 years
• babies less than 72 hours old with a confirmed bacterial infection
• babies with a high risk of developing a bacterial infection
• people with heart failure
• people who have to take insulin to control their diabetes
• people with a weakened immune system

Bites or wounds

Antibiotic prophylaxis may be recommended for a wound that has a high chance of becoming infected. This could be an animal or human bite, for example, or a wound that has come into contact with soil or faeces.

Medical conditions

There are several medical conditions that make people particularly vulnerable to infection. This makes antibiotic prophylaxis necessary.

The spleen plays an important role in filtering out harmful bacteria from the blood. If your spleen doesn't work properly, this means antibiotics can help prevent infection.

People more vulnerable to infection include those:

• who've had their spleen removed
• having chemotherapy for cancer
• with the blood disorder sickle cell anaemia

Recurring infection

Antibiotic prophylaxis may also be recommended for a recurring infection, like:

• cellulitis
• a urinary tract infection
• genital herpes
• rheumatic fever

Types of antibiotics

There are many different types of antibiotic. Most can be put into 6 different groups.

Penicillins

These are widely used to treat a variety of infections, including:

• skin infections
• chest infections
• urinary tract infections

Cephalosporins

These can be used to treat a wide range of infections. Some are also effective for treating more serious infections, like:

• septicaemia
• meningitis

Aminoglycosides

These are usually used in hospital to treat very serious illnesses like septicaemia. This is because they can cause serious side effects like hearing loss and kidney damage.

Aminoglycosides are usually given by injection. They may also be given as drops for some ear or eye infections.

Tetracyclines

These can be used to treat a wide range of infections. They are commonly used to treat moderate to severe acne and rosacea.

Macrolides

These can be particularly useful for treating lung and chest infections.

Macrolides are used as an alternative for people with a penicillin allergy. They can also be used to treat penicillin-resistant strains of bacteria

Fluoroquinolones

These are broad-spectrum antibiotics that can be used to treat a wide range of infections.

Your GP or pharmacist will tell you how to take your antibiotics. You should also follow the instructions on the packet or patient information leaflet. The patient information leaflet comes in the packet with your medicine.

Antibiotics can be given in different ways, including:

• oral - tablets, capsules or liquids that treat most mild to moderate infections
• topical – creams, lotions, sprays or drops that treat skin infections
• injections – given directly into the blood or muscle for more serious infections

Missing a dose of antibiotics

If you forget to take a dose of your antibiotics, take that dose as soon as you remember. You should then continue to take your course of antibiotics as normal.

If it's almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Don't take a double dose to make up for a missed one.

There's an increased risk of side effects if you take 2 doses closer together than recommended.

Accidentally taking an extra dose

If you accidentally take one extra dose of your antibiotic it's unlikely to cause serious harm. However, it will increase your chances of side effects like:

• pain in your stomach
• diarrhoea
• feeling or being sick

Antibiotic resistance

Antibiotics are no longer routinely used to treat infections because:

• many infections are caused by viruses, so antibiotics aren't effective
• antibiotics are often unlikely to speed up the healing process
• antibiotics can cause side effects

The overuse of antibiotics in recent years also means they're becoming less effective. This has led to the emergence of "superbugs". These are strains of bacteria that have developed resistance to many different antibiotics. Superbugs include:

• methicillin-resistant Staphylococcus aureus (MRSA)
• Clostridium difficile (C. diff)
• the bacteria that cause multi-drug-resistant tuberculosis (MDR-TB)
• carbapenemase-producing Enterobacteriaceae (CPE)

These types of infections can be serious and challenging to treat.

The worry is that new strains of bacteria will develop that antibiotics won't be able to treat.

The most common side effects of antibiotics affect the digestive system. Symptoms can include:

• vomiting
• nausea (feeling sick)
• diarrhoea
• bloating
• indigestion
• abdominal pain
• loss of appetite

These side effects are usually mild and should pass once you finish your course of treatment.

If you experience any other side effects, contact your GP or the doctor in charge of your care for advice.

Antibiotic allergic reactions

Some people have an allergic reaction to antibiotics, especially penicillin and cephalosporins. In most cases, the allergic reaction is mild to moderate and can cause:

• a raised, itchy skin rash (urticaria, or hives)
• coughing
• wheezing
• tightness of the throat, which can cause breathing difficulties

Mild to moderate allergic reactions can usually be treated by taking antihistamines.

In rare cases, an antibiotic can cause anaphylaxis. This is a severe and potentially life-threatening allergic reaction. Anaphylaxis is a medical emergency and prompt treatment should be given.

Interactions

Some antibiotics can interact with other substances and medicines.

Alcohol

You should not drink alcohol while taking the antibiotics, especially metronidazole or tinidazole.

You shouldn't drink alcohol for 48 hours after stopping your antibiotics.

This combination can cause very unpleasant side effects, like:

• feeling and being sick
• stomach pain
• hot flushes
• headaches

Combined oral contraceptives

Some antibiotics can reduce the effectiveness of the combined oral contraceptive pill. This includes the antibiotics rifampicin and rifabutin.

If you're prescribed these antibiotics, you may need to use additional contraception like condoms. Speak to your GP, nurse or pharmacist for advice.

Medications

Antibiotics can sometimes interact with other medicines or substances. This means it can have an effect that is different from what you expected.

If you want to check that your medicines are safe to take with your antibiotics, ask your GP or local pharmacist.

Considerations

There are some important things to consider when taking antibiotics.