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Penicillin V

Also called phenoxymethylpenicillin

Key points about penicillin V

Penicillin V is an antibiotic used to treat different infections caused by bacteria.
Penicillin V belongs to a group of antibiotics called penicillins.
Penicillin V is also called phenoxymethylpenicillin.
Find out how to take it safely and possible side effects.

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Penicillin V is an antibiotic used to treat bacterial infections (eg, infections of the throat and chest) and skin infections (eg, cellulitis). It's also given to prevent infection if you've had rheumatic fever, or if you have a weakened immune system (eg, if you have had your spleen removed). Penicillin V works by killing or stopping the growth of bacteria (bugs). Like all antibiotics, penicillin V is not effective against infections caused by viruses.

Allergy to penicillin

Penicillin V belongs to a group of antibiotics called penicillins.

Before taking Penicillin V: Tell your healthcare provider if you have had an allergic reaction to a medicine, especially a penicillin antibiotic. True penicillin allergy is rare – fewer than 5 out of 10,000 people are allergic to penicillin. Most people who think they have a penicillin allergy do not – read more about penicillins and penicillin allergy(external link).
After taking Penicillin V: If you develop signs of an allergic reaction such as skin rash, itching, swelling of your lips, face and mouth, or difficulty breathing, stop taking Penicillin V and seek immediate medical attention.

Dose

Always take your penicillin V exactly as your doctor has told you. The pharmacy label on your medicine will tell you how much to take, how often to take it, and any special instructions.

In Aotearoa New Zealand, penicillin V is available as capsules and liquid.
The dose of penicillin V will be different for different people depending on the type of infection and your age.
Adults: the usual dose is 500 mg 4 times a day. For a severe infection, you may need 1 gram 4 times a day.
Children: the dose for children will depend on their body weight. It is usually given 2 to 4 times a day.
Your doctor will advise you on how long to take penicillin V for. It is usually taken for 10 days, but some people require longer treatment.

How to take penicillin V

Penicillin V is best taken 1 or 2 hours before eating food. This is because your body may absorb less penicillin V after a meal, making it less effective.
Capsules: Swallow the capsule with a glass of water. Do not chew them.
Liquid: Shake the medicine well. Measure the right amount using an oral syringe or medicine spoon. You can get these from your pharmacy. Do not use a kitchen spoon as it will not give you the right amount. Read more: Tips on how to give medicines to babies and children.
Timing: Take penicillin V at the same times each day. Try to space your doses evenly throughout the day.
- Twice a day: This should be in the morning and in the evening.
- Three times a day: This should be in the morning, early afternoon and at bedtime.
- Four times a day: This should be about 4 hours apart, for example 7am, 11am, 3pm and 7pm.
Missed dose: If you forget to take your dose at the correct time, take it as soon as you remember. Try to take the correct number of doses each day. Don't take 2 doses at the same time to make up for a forgotten dose.
If you are sick: If you are sick (vomit) less than 30 minutes after having a dose of penicillin V, take the same dose again. But, if you are sick more than 30 minutes after taking your dose, you don't need to take another dose. Just take the next one when it's due. If you are vomiting and are worried, contact your doctor or call Healthline (0800 611 116) for advice.
Finish the course: It's best to take the whole course of antibiotics for the number of days your doctor has told you to. Don't stop taking it, even if you feel your infection has cleared up.

Here are some things to know when you're taking penicillin V. Other things may be important as well, so ask your healthcare provider what you should know about.

Taking other medicines and supplements

Penicillin V can interact with some medications, herbal supplements and rongoā Māori, so check with your doctor or pharmacist before starting penicillin V and before starting any new products.
If you're taking the contraceptive pill, 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 happens, ask your doctor or pharmacist for advice about contraception over the following few days.

Storage

Store your capsules in a cool, dry place, away from direct heat and light. If you have been given liquid medicine, this will have been made up by the pharmacy and you may need to keep it in the fridge – check the instructions on the bottle. Make sure the medicine doesn't freeze.

Like all medicines, penicillin V can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.

Side effects	What should I do?
Diarrhoea (runny poo), nausea (feeling sick)	These usually go away with time. Tell your doctor if they bother you.
Tummy upset	Try taking your dose with a small amount of food.
Fever, joint pain	Tell your doctor or ring Healthline 0800 611 116.
Vaginal itching, soreness or discharge (vaginal thrush)	Tell your doctor or pharmacist.
White or yellow spots or sores in the mouth, or red, painful gums (oral thrush)	Tell your doctor or pharmacist
Allergic reaction such as skin rash, itching, swelling of the lips, face, and mouth or difficulty breathing	Stop taking penicillin V. Tell your doctor immediately or ring Healthline 0800 611 116.