Taking antibiotics as prevention

Antibiotics are the most common kind of medicine prescribed in the UK. They are a group of medicines that act against bacteria. Different types of antibiotics work in different ways, but they either kill off the bacteria or stop them growing and multiplying. They are mainly prescribed for a short ‘course’ to treat bacterial infections, often throat, chest or urine infections. Antibiotics can also be taken to prevent a bacterial infection developing.

For example, they are often prescribed to prevent frequent urinary tract infections (UTIs). Examples of antibiotics can include trimethoprim, co-trimoxazole, nitrofurantoin and cefalexin. Antibiotics do not work against viral or fungal infections and so should not be prescribed for these.

How are antibiotics given?

They are given by mouth in the form of a liquid or a tablet. You should give the dose to your child as stated on the label. If your child is taking antibiotics as prevention, the dose will need to be increased as your child grows. You will be asked to have your child weighed and measured at your family doctor (GP) surgery regularly and to report to your doctor.

Are there any side effects to antibiotics?

Antibiotics are very safe and have few side effects at the dosage given to prevent infection. The package insert will explain about possible side effects. If you are concerned, please talk to your doctor, nurse or pharmacist.

Common side effects

Upset tummy

Antibiotics can cause an upset tummy, but giving the medicine with or after food can reduce this.

Less common side effects

Alterations to the blood

Rarely, some antibiotics can alter the number of blood cells being produced, causing anaemia. If your child seems unusually tired, has bruising or bleeding, or any signs of infection, especially a high temperature, please tell your family doctor (GP).

Allergic reaction

Some children receiving antibiotics may have an allergic reaction. This reaction may be mild to severe. Signs of a mild allergic reaction include skin rashes and itching, high temperature, shivering, redness of the face, a feeling of dizziness or a headache. If you see any of these signs, please report them to a doctor or nurse.

Signs of a severe allergic reaction include any of the above, as well as shortness of breath or chest pain. If you are in hospital and your child shows signs of a severe allergic reaction, call a doctor or nurse immediately. If you are at home and your child shows signs of a severe allergic reaction, call an ambulance immediately. If your child has a severe reaction to a particular antibiotic, subsequent treatment will be changed.

Sensitivity to sunlight

While your child is taking some antibiotics, his or her skin may burn more easily than usual. You should avoid your child being exposed to sunlight or other forms of ultraviolet light. If your child does go out in the sun, always use a good sun block of SPF 25 or higher and ensure that they wear a sun hat.

Important information about antibiotics

  • Ask your pharmacist about storing the medicine. Some need to be kept in the fridge but others only need to be kept out of direct sunlight. Always store medicines in a safe place where children cannot reach them.
  • If your child has any allergies to food, medicines, preservatives or colouring, please tell us.
  • While your child is taking medicines, it is important that you tell your doctor, nurse or pharmacist about any other medicines your child is taking. This includes medicines on a prescription from your GP, medicines bought from a chemist or any homeopathic or herbal medicines.
  • Your child should continue to take the antibiotics until advised otherwise.
  • If you forget to give your child their dose, give it as soon as you remember but if the next dose is due, do not give him or her the missed dose and keep to your child’s regular schedule.
  • In certain circumstances, medicines may be prescribed for a child outside the age range recommended by the manufacturer. Medicines are often used ‘off licence’ in children because trial data is not available for a specific use, for example, in children of a certain age. If you have any concerns about this, please discuss with your doctor.
  • Some antibiotics can cause damage to the unborn baby. If your daughter is ten years old or older, we will ask her about her periods and any possibility that she could be pregnant. If your daughter is sexually active, she must use a reliable form of contraception, as antibiotics can reduce the effectiveness of the contraceptive pill.
  • Always check that you have enough medicine and remember to order a new prescription in plenty of time.
  • Check the expiry date on the medicine before giving it to your child. If it passes its expiry date or your child stops using it, please return it to your pharmacist. Do not flush it down the toilet or throw it away.
Compiled by: 
The Pharmacy department in collaboration with the Child and Family Information Group, GOSH.
Last review date: 
July 2013


Please read this information sheet from GOSH alongside the patient information leaflet (PIL) provided by the manufacturer. If you do not have a copy of the manufacturer’s patient information leaflet please talk to your pharmacist. A few products do not have a marketing authorisation (licence) as a medicine and therefore there is no PIL.

For children in particular, there may be conflicts of information between the manufacturer’s patient information leaflet (PIL) and guidance provided by GOSH and other healthcare providers. For example, some manufacturers may recommend, in the patient information leaflet, that a medicine is not given to children aged under 12 years. In most cases, this is because the manufacturer will recruit adults to clinical trials in the first instance and therefore the initial marketing authorisation (licence) only covers adults and older children.  

For new medicines, the manufacturer then has to recruit children and newborns into trials (unless the medicine is not going to be used in children and newborns) and subsequently amend the PIL with the approved information. Older medicines may have been used effectively for many years in children without problems but the manufacturer has not been required to collect data and amend the licence. This does not mean that it is unsafe for children and young people to be prescribed such a medicine ‘off-licence/off-label’. However, if you are concerned about any conflicts of information, please discuss with your doctor, nurse or pharmacist.