Antibiotics attack bacteria, which are germs responsible for many different infections. There are many different bacteria and many different antibiotics. Each antibiotic attacks different types of bacteria and will be useful for treating particular infections. Some are broad spectrum, affecting a wide range of bacteria – and some are narrow spectrum, affecting only a few types. Antibiotics can be life-saving in the case of serious infections, but they can also have harmful side effects. Overuse of antibiotics can lead to antibiotic resistance, making them less effective in the future.
Antibiotics don’t kill virusesNot all infections are due to bacteria. Many, such as the common cold, flu, glandular fever and chickenpox, are due to viruses. Antibiotics do not affect viruses and are of no use in treating viral infections. Most simple coughs and colds do not need antibiotic treatment. It is sometimes not possible to be certain if an infection has a bacterial or viral cause. In these circumstances, your doctor’s experience and findings after examining you, and possibly testing for the cause of infection, will determine if antibiotics are needed.
Common infections and antibioticsMany infections will clear up by themselves without the need for antibiotics. And many infections are caused by viruses – so antibiotics won’t work. Your doctor weighs these things up when they decide whether or not to prescribe antibiotics for your infection. You may wonder why not prescribe anyway, ‘just in case’? But there are consequences to inappropriate prescribing of antibiotics:
- bacteria develop resistance to antibiotics, making the drugs ineffective
- you may suffer an adverse reaction to the antibiotics.
Do I need a prescription for antibiotics?In Australia, antibiotics need to be prescribed by a doctor. But in Queensland, there are some very specific uses (antibiotics for urinary tract infections), where a pharmacist may dispense antibiotics without a prescription.
Do I have to finish the course or not?When you are prescribed a course of antibiotics, it is important to take the full course as directed by your doctor, even if you start feeling better after a day or 2. This way, the bacteria will be fully exterminated, and the risk of recurrence reduced. If you stop before the course is finished, there is a risk of the bacteria becoming resistant to the antibiotic. Antibiotics can take the form of tablets, capsules, creams, injections or be given intravenously. Some antibiotics should be taken with food, and others need to be taken on an empty stomach. Always check the instructions on the pack or ask your pharmacist.
What if I miss a dose?Ideally, your doses of antibiotics should be as evenly spaced out as possible to maintain the concentration of drug in your body. If you miss a dose of your antibiotics or accidentally take 2 doses, your pharmacist will be able to advise what you should do, or the Consumer Medicines Information leaflet in the pack may have instructions.
Side effectsAlthough antibiotics are generally very safe medicines, side-effects can sometimes occur. These are usually mild. The side effects that may be experienced with the antibiotic you are taking will be explained in the Consumer Medicines Information leaflet in the pack. If you have any concerns about side effects, talk to your pharmacist or doctor. Common side effects of antibiotics include:
- mild stomach upset
- vaginal thrush in women, and
Do antibiotics affect the oral contraceptive pill?Some antibiotics, such as rifampicin, may affect the oral contraceptive pill, making it less effective. The Consumer Medicines Information leaflet that comes with your antibiotics will have a warning if this is the case, or your pharmacist or doctor will be able to advise. You may need to use additional contraception, such as condoms, while this is the case or use a different method of contraception. If the antibiotics have caused you to vomit or have diarrhoea, as a side effect, then your contraceptive pill may not have been absorbed by your body and won’t be effective at protecting you from getting pregnant.
Allergic reactionsSome people are allergic to certain antibiotics. This can result in a rash such as hives, and occasionally swelling of the lips or tongue developing soon after taking the antibiotic (usually within one hour). Very rarely, an allergic reaction to antibiotics results in a severe reaction with collapse and breathing difficulties – anaphylaxis. Rashes that appear after taking an antibiotic are not always due to allergy – they may be due to the illness itself. If you develop a rash after taking an antibiotic, talk to your doctor. If any reaction is rapid and severe, call 000 for an ambulance. Penicillin allergy can cause rash, itching and hives, as well as more severe reactions, including anaphylaxis. These reactions normally happen within an hour of taking the drug. But also, like other antibiotics, penicillin can cause side effects that aren’t allergic reactions.
Antibiotics and alcoholDrinking alcohol when you’re unwell or taking medication is not generally a good idea. But, in addition, alcohol can cause a serious dangerous reaction if you drink it when you are taking certain antibiotics. Always read the warnings on your medicine label. Alcohol must not be used when you are taking some medicines, including:
- metronidazole (brand names include Flagyl, Metrogyl, Metronide) or
- tinidazole (brand names Fasigyn, Simplotan).