Make sure you tell your doctor if you are allergic to penicillin. Ampicillin is a type of penicillin - do not take it if you are allergic to penicillin.
Space your doses out evenly over the day and complete the full course of the antibiotic, even if you feel your infection has cleared up. You should take ampicillin when your stomach is empty of food (so an hour before you eat, or two hours afterwards).
If you have an allergic reaction (such as any swelling around your mouth, any difficulties breathing or a red rash) contact a doctor straightaway.
|Type of medicine||A penicillin antibiotic|
|Used for||Infections (in adults and children)|
In combination with flucloxacillin: co-fluampicil
|Available as||Capsules, oral liquid medicine and injection|
Ampicillin is given to treat a bacterial infection. It is mainly prescribed for sinus and chest infections, urine infections, and ear infections. It is a penicillin antibiotic which treats infection by killing the germs (bacteria) responsible for the infection.
Ampicillin is also available in combination with another penicillin antibiotic called flucloxacillin. The combination is called co-fluampicil.
Before taking ampicillin
Some medicines are not suitable for people with certain conditions, and sometimes a medicine can only be used if extra care is taken. For these reasons, before you start taking ampicillin it is important that your doctor knows:
- If you suspect you may have glandular fever (the symptoms are high temperature (fever), sore throat, swollen glands).
- If you have an allergic condition, or if you have ever had an allergic reaction to a medicine. This is especially important if you have ever had a bad reaction to any penicillin antibiotic.
- If you have any problems with the way your kidneys work.
- If you are pregnant or breastfeeding. Ampicillin is not known to be harmful to babies; however, it is still important that you tell your doctor if you are expecting or breastfeeding a baby.
- If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.
How to take ampicillin
- Before you start the treatment, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about ampicillin and will provide you with a full list of the side-effects which you may experience from taking it.
- Take ampicillin exactly as your doctor tells you to. It is usually taken four times a day, every six hours. Your doctor or pharmacist will tell you how you should take the medication, and this information will be printed on the label of the pack to remind you. It is important that you space out the doses evenly during the day. Swallow the capsules with a drink of water.
- You should take ampicillin when your stomach is empty, which means taking your doses one hour before you eat any food, or waiting until two hours afterwards. This is because your body absorbs less ampicillin after a meal, which means the medicine is less effective.
- If you have been given liquid medicine for a child, read the directions carefully to make sure you measure out the correct amount of medicine.
- If you forget to take a dose, take one as soon as you remember. Try to take the correct number of doses each day, but do not take two doses at the same time to make up for a forgotten dose.
Getting the most from your treatment
- Even if you feel your infection has cleared up, keep taking the antibiotic until the course is finished (unless a doctor tells you to stop). This is to prevent the infection from coming back.
- Antibiotics are prescribed in short courses of treatment. Your doctor will tell you how long your course of treatment will last - this is not usually for longer than 14 days. If you still feel unwell after finishing the course, go back to see your doctor.
- Some people develop redness and itching in the mouth or vagina (thrush) after taking a course of antibiotics. If this happens to you, speak with your doctor or pharmacist for advice.
- If you are taking the contraceptive 'pill' at the same time as this antibiotic, the effectiveness of the 'pill' can be reduced if you have a bout of being sick (vomiting) or diarrhoea which lasts for more than 24 hours. If this should happen, ask your doctor or pharmacist for advice about what additional contraceptive precautions to use over the next few days. There is no need to use additional precautions for any bouts of sickness or diarrhoea which last for less than 24 hours.
- Ampicillin can stop the oral typhoid vaccine from working. If you are due to have any vaccinations, make sure the person treating you knows that you are taking this antibiotic.
Can ampicillin cause problems?
Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with ampicillin. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.
|Common ampicillin side-effects (these affect fewer than 1 in 10 people)||What can I do if I experience this?|
|Feeling sick (nausea) or being sick (vomiting)||Stick to simple foods|
|Diarrhoea||Drink plenty of water to replace any lost fluids. If the diarrhoea continues, becomes severe, or contains blood, let your doctor know straightaway|
|Redness and itching in the mouth or vagina (thrush)||Speak with a pharmacist or your doctor for advice about treatment|
|Skin rash||Let your doctor know as soon as possible as your treatment will need to be changed|
Important: if you develop an itchy rash, swollen face or mouth, or have difficulty breathing, these may be signs that you are allergic to a penicillin antibiotic. Do not take any more ampicillin and speak with your doctor or go to your local accident and emergency department straightaway.
If you experience any other symptoms which you think may be due to the antibiotic, speak with your doctor or pharmacist for further advice.
How to store ampicillin
- Keep all medicines out of the reach and sight of children.
- Store in a cool, dry place, away from direct heat and light.
- If you have been given liquid medicine, store it in a refrigerator. It will have been made up by the pharmacy and lasts for seven days, so check the expiry date on the bottle and do not use it after this date.
Important information about all medicines
Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital at once. Take the container with you, even if it is empty.
This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.
If you buy any medicines, check with a pharmacist that they are safe to take with your other medicines.
If you are having an operation or any dental treatment, tell the person carrying out the treatment which medicines you are taking.
Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.
If you have any questions about this medicine ask your pharmacist.
Further reading and references
Manufacturer's information for healthcare professionals (SPC), Penbritin (Ampicillin) 250 mg capsules; Chemidex Pharma Ltd, The electronic Medicines Compendium. Dated October 2015.
British National Formulary, 83rd Edition (Mar 2022); British Medical Association and Royal Pharmaceutical Society of Great Britain, London.