This post is also available in: Svenska
Sometimes children need penicillin such as Penicillin VK (phenoxymethylpenicillin), Floxapen (flucloxacillin) or Amoxil (amoxicillin). Penicillin is a class of antibiotics which treat bacterial infections such as otitis, pneumonia, tonsillitis, urinary tract infection and impetigo. But they also fight against dangerous infections such as septicemia and meningitis. Penicillin is completely ineffective against viral infections, such as colds, RS-virus infection, gastroenteritis, hand-foot-and-mouth and chickenpox.
In life-threatening infections, penicillin can be lifesaving. For minor infections, it can shorten the duration of the disease or reduce the risk of complications. If your child has been prescribed antibiotics, ensure that the doctor is treating your child’s infection specifically.
Different antibiotics for different bacteria
Different antibiotic varieties are active against different bacteria. Sometimes doctors choose antibiotics after a bacterial cultural response, where they have tested which antibiotics are active against the particular bacteria that is causing the infection in your child. However, the test takes a day or two to get a response. So usually children are given antibiotics that commonly work for the bacteria which commonly causes the infection.
Narrow- and broad-spectrum antibiotics
Narrow-spectrum antibiotics are only effective against a specific bacterial group while broad-spectrum antibiotics are effective against a wide-range of disease-causing bacteria. The more serious the infection, the more fragile the patient and the more unclear it is which bacteria is causing the infection. That’s when the broader antibiotics are chosen. The problem with many broad antibiotic varieties is that bacteria develop resistance to them. Thus they eventually become ineffective against certain bacteria.
Penicillin VK (phenoxymethylpenicillin) – perfect for most respiratory infections
Penicillin VK (phenoxymethylpenicillin) is a narrow-spectrum antibiotic. It has a fast and powerful effect against the most common and dangerous respiratory bacteria. When treating otitis, the most important bacteria involved is streptococcus. This bacteria is also a common respiratory bacteria that can cause serious otitis, blood poisonings, pneumonias and throat infections. Penicillin VK is super effective against streptococcus, there is nothing better!
Read more about streptococcus in children
Other bacteria such as Hemofilus influenzae and Moraxella catharralis can also cause otitis. But they are not nearly as aggressive, and generally do not cause any complications in otherwise healthy children. Therefore, our priority is to treat the streptococcus.
Read more about otitis in children
Penicillin VK is also beneficial from a resistance and side effect point of view. There is a low risk that the child will develop resistant bacteria after a Penicillin VK treatment compared to other broader spectrum antibiotics.
Penicillin VK (phenoxymethylpenicillin) is very effective, even against skin manifestations of borrelia.
Read more about lyme disease in children
But Penicillin VK tastes so bad…
Unfortunately, it does. We can all agree on that. Penicillin is extracted from a mold fungus and the taste of the mold does not go away. And in liquid form, it is not possible to hide the taste, no matter what flavors you add. It’s good to know though, that liquid Penicillin VK is available in different concentrations, and the more concentrated it is, the less you have to give.

This is an example I give to parents in Sweden. So if you have been given a prescription for 10 ml of Kåvepenin fruit (Penicillin VK 50 mg/ml) daily, you can ask for a prescription for Kåvepenin oral drops (Penicillin VK 250 mg/ml), of which you only need to give 2 ml for the same effect.
Read more about how to give children medicine
Floxapen (flucloxacillin) – narrow spectrum and good for skin infections
Many skin infections are caused by the bacteria Staphylococcus aureus, the yellow staphylococcus. Staphylococcus aureus can break Penicillin VK down, which renders the antibiotic ineffective. Therefore, Penicillin VK is a bad option against most skin infections, while Floxapen (flucloxacillin) works.
Read more about impetigo in children
Unfortunately, though, it does taste as bad as Penicillin VK, if not worse. And it is not available in different strengths, but in very small tablets that even small children are usually able to take. In Sweden, Penicillin VK is also available in equally small tablets. The tablets can be crushed, but some of its flavor is released. Ask your pharmacist or doctor for advice.
Amoxil (amoxicillin) – sometimes an alternative to Penicillin VK
Amoxil (amoxicillin) is effective against more bacteria than Penicillin VK, and is usually used when Penicillin VK has not helped against, for example, otitis. Luckily for us, Amoxil tastes good, and most children like it. The reason why you don’t give Amoxil to everyone is that it is “broader” than Penicillin VK which means that it runs the risk of developing bacterial resistance.
Erythrocin (erythromycin) – for pertussis, mycoplasma or used in case of genuine allergy to penicillin
Erythrocin (erythromycin) is a completely different class of antibiotic compared to Penicillin VK. It works against certain bacteria which Penicillin VK is completely ineffective against. Erythrocin works against whooping cough, mycoplasma infections and more, in addition to the usual streptococcus and what Penicillin VK works against.
The problem with Erythrocin is that it has a direct impact on intestinal motility and thus causes stomach aches, diarrhea and nausea. These problems are less likely to happen when the medicine is given in capsule form instead of liquid form. You can open the capsule and give the small granules directly if you want.
In the case of genuine severe penicillin allergy, Erythrocin may be the best option. But suspected penicillin allergy should always be investigated with blood tests, prick tests and almost always under supervision to see what happens. Most suspected penicillin allergies are not genuine allergies. Thus it would be unnecessary to give Erythrocin with all its side effects.
Penicillin is good when necessary, otherwise refrain
The next time your child is prescribed an antibiotic treatment, ask your doctor how important is it really. What are the risks of abstaining? Can you wait a few days and see if the child can cope with the infection without antibiotics? In many cases (but not all), you can avoid taking penicillin as long as you are vigilant with how the child is feeling and if you are able to seek medical care again in case of deterioration. But always agree on it with the doctor! And if the child has started an antibiotic, complete the course to avoid a relapse or to reduce the risk of developing a resistance.
Read more about antibiotic resistance here
Read more:
Streptococcus in children – tonsillitis, perianal strep, scarlet fever
Otitis in children – symptoms and treatment
Lyme disease in children – symptoms & treatment
Impetigo in children – infection and treatment
Tips for giving children medicine