Antibiotics. How do antibiotics work? What are they for? Side effects

Antibiotics, sometimes known as antibacterials, are drugs used to treat infections caused by bacteria. These are tiny organisms, too small to see with the naked eye, that sometimes cause illness in humans. Well-known illnesses caused by bacteria include tuberculosis, salmonella, syphilis and some forms of meningitis. However many types of bacteria do not cause illness and live harmlessly on, and in, the human body. Our immune systems, with their antibodies and special white blood cells, can usually kill harmful bacteria before they multiply enough to cause symptoms. And even when symptoms do occur, the body can often fight off the infection. But sometimes the body is overwhelmed by a bacterial infection and needs help to get rid of it. This is where antibiotics come in. The very first antibiotic was penicillin and along with a family of related antibiotics (such as ampicillin, amoxicllin and benzylpenicillin) it is still widely used to treat many common infections. Now there are several other different kinds of antibiotics. All of them are only available on prescription. HOW DO ANTIBIOTICS WORK? Some antibiotics, such as the penicillins, are 'bactericidal', meaning that they work by killing bacteria. They do this by interfering with the formation of the cell walls or cell contents of the bacteria. Other antibiotics are 'bacteriostatic', meaning that they work by stopping bacteria multiplying. WHAT ARE ANTIBIOTICS FOR? Antibiotics are usually used to treat infections caused by bacteria. They do not work against other organisms such as viruses or fungi. It's important to bear this in mind if you think you have some sort of infection, because many common illnesses, particularly of the upper respiratory tract such as the common cold and sore throats, are usually caused by viruses. Overuse of antibiotics can lead to bacteria becoming resistant to them so it's important to only take them when necessary. Some antibiotics can be used to treat a wide range of infections and are known as 'broad-spectrum' antibiotics. Others are only effective against a few types of bacteria and are called 'narrow-spectrum' antibiotics. Some antibiotics work against aerobic bacteria, that is organisms that need oxygen to live, while others work against anaerobic bacteria, organisms that don't need oxygen. Sometimes antibiotics are given to prevent an infection occurring, for example, before certain operations. This is known as prophylactic use of antibiotics and is common before orthopaedic and bowel surgery. SIDE EFFECTS OF ANTIBIOTICSThe most common side effects with antibiotic drugs are diarrhoea, feeling sick and being sick. Fungal infections of the mouth, digestive tract and vagina can also occur with antibiotics because they destroy the protective 'good' bacteria in the body (which help prevent overgrowth of any one organism), as well as the 'bad' ones, responsible for the infection being treated. Rare, but more serious side effects, include the formation of kidney stones with the sulphonamides, abnormal blood clotting with some of the cephalosporins, increased sensitivity to the sun with the tetracyclines, blood disorders with trimethoprim, and deafness with erythromycin and the aminoglycosides. Sometimes, particularly in older people, antibiotic treatment can cause a type of colitis (inflamed bowel) leading to severe diarrhoea. Penicillins, cephalosporins and erythromycin can all cause this problem but it is most common with clindamycin, an antibiotic usually reserved for serious infections. If you develop diarrhoea while taking an antibiotic, immediately contact your doctor. Some people are allergic to antibiotics, particularly penicillins, and can develop Side effects such as a rash, swelling of the face and tongue, and difficulty breathing when they take them. Always tell your doctor or pharmacist if you have had an allergic reaction to an antibiotic; sometimes the reaction can be serious or even fatal. This is called an anaphylactic reaction. USE ANTIBIOTICS WITH CARE IF ... You should use an antibiotic with care if you have reduced liver or kidney function. You should avoid using any antibiotic to which you have previously had an allergic reaction. TELL YOUR DOCTOR OR PHARMACIST IF YOU ARE PREGNANT OR BREASTFEEDING BEFORE TAKING ANY ANTIBIOTIC. INTERACTIONS WITH OTHER MEDICINESDo not take any other medicines or herbal remedies with an antibiotic, including those you have bought without a prescription, before talking to your doctor or pharmacist. -- Certain antibiotics (e.g. penicillins, cephalosporins) can reduce the effectiveness of oral contraceptives. If you have diarrhoea or vomiting while taking an antibiotic, the absorption of the pill can be disrupted. In either case, you should take additional contraceptive precautions while you are taking the antibiotic. -- There are a number of important interactions between antibiotics and other medicines so it's important to tell which your doctor or pharmacist about any other medicines you are taking. HOW TO USE AN ANTIBIOTICAntibiotics are usually taken orally but can also be given by injection, or applied to the affected part of the body such as the skin, eyes or ears. The drugs begin to tackle most infections within a few hours. It is vital to take the whole course of treatment to prevent recurrence of the infection. Sometimes bacteria become 'resistant' to an antibiotic you have been taking, meaning that the drug will no longer work. Resistance tends to occur when the bacterial infection responsible for the symptoms is not completely cured, even if the symptoms have cleared up. Some of the residual bacteria, having been exposed to, but not killed by, the antibiotic are more likely to grow into an infection that can survive that particular antibiotic. This explains why finishing the course of antibiotics, even if you feel better, is important. Certain antibiotics should not be taken with certain foods and drinks. Some antibiotics are best taken when there is no food in your stomach, usually an hour before meals or two hours after - make sure you follow the instructions on the dispensing label. Do not drink alcohol if you are taking metronidazole. Do not take tetracyclines with dairy products, as these can reduce the absorption of this type of antibiotic.