Hesperian Health Guides

Newborn Babies and Breastfeeding: Medicines

Newborn Babies and Breastfeeding: Medicines

Antibiotics Fight Infection

Ampicillin and amoxicillin

Ampicillin and amoxicillin are broad-spectrum penicillins, which means they kill many kinds of bacteria. The two are often interchangeable. When you see a recommendation for ampicillin, you will often be able to use amoxicillin in its place, in the correct dose (see below).

Ampicillin and amoxicillin are very safe and are especially useful for babies and small children. They are both useful in treating pneumonia or ear infections. Ampicillin is also useful in treating meningitis and other severe infections in newborns.

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Both these medicines, but especially ampicillin, tend to cause nausea and diarrhea. Avoid giving them to children who already have diarrhea if you can give another antibiotic instead.

The other common side effect is rash. But raised, itchy bumps that come and go in a few hours are probably a sign of penicillin allergy. Stop giving the medicine right away and do not give the child a penicillin medicine again. Future allergic reactions may be more severe and even life-threatening. For some problems erythromycin can be used instead. A flat rash that looks like measles, and usually appears a week after starting the medicine and takes days to go away, is not necessarily an allergy. But it is impossible to know for sure if the rash is from an allergy or not, so it is usually better to stop taking the medicine.


Resistance to these medicines is growing more common. Depending on where you live, they may not work any more against staphylococcus, shigella, or other infections.

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Ampicillin and amoxicillin work well when taken by mouth. To give tablets or capsules to a baby, crush the pills or empty the capsules and divide the powder to get the amount you need. Then mix it into a little breast milk. Feed the milk and medicine to the baby with a cup or spoon. Ampicillin can also be given by injection, but should only be injected for severe illnesses such as meningitis, or when the person is vomiting or cannot swallow.

As with other antibiotics, always give these medicines for at least the shorter number of days shown here. If the person still has signs of infection, have her continue taking the same amount every day until all signs of infection have been gone for at least 24 hours. If the person has taken the medicine for the maximum number of days and is still sick, stop giving the antibiotic and get medical help. For people with HIV, always give the medicine for the maximum number of days listed.

Likewise the amount of antibiotic to take depends on the age or weight of the person and the severity of the infection. In general, give the smaller amount for a thinner person or for a less severe infection, and the larger amount for a heavier person or a more severe infection.

For most newborn infections
Give 62 mg, 3 times a day for 3 to 7 days. Each dose is:
¼ of a 250 mg capsule OR
½ teaspoon (2.5 ml) of 125 mg/5 ml syrup OR
¼ teaspoon (1.25 ml) of 250 mg/5 ml syrup.

For most newborn infections
Give 125 mg, 3 times a day for 3 to 7 days. Each dose is:
½ of a 250 mg capsule OR
1 tsp (5 ml) of 125 mg/5 ml syrup.

For severe infections in newborns such as meningitis
Inject a combination of ampicillin and gentamicin in the side of the thigh muscle. See Medicines, Tests, and Treatments (in development) for how to inject.

Dilute a 500 mg vial of ampicillin with 2.1 ml sterile water. This makes a concentration of 500 mg per 2.5 ml.

Use an undiluted 2 ml vial of gentamicin at 40 mg per ml.


Gentamicin is a very strong antibiotic of the aminoglycoside family. It can only be given by injection or IV (in the vein). This drug can damage the kidneys and the hearing, and therefore should only be used in emergencies on the way to get medical help. If the baby is dehydrated, also give breast milk and rehydration drink immediately.

For a baby less than 1 week old
AMPICILLIN: Inject 50 mg per kg, 2 times a day for at least 5 days,
GENTAMICIN: Inject 5 mg per kg, once a day for at least 5 days.
Do not give for more than 10 days.
For a baby 1 week to 1 month old
AMPICILLIN: Inject 50 mg per kg, 3 times a day for at least 5 days,
GENTAMICIN: Inject 7.5 mg per kg, once a day for at least 5 days.
Do not give for more than 10 days.


Erythromycin works against many of the same infections as penicillin and can be used by those who are allergic to penicillins. For many infections it can also be used in place of tetracycline. It can also be used for diphtheria and pertussis (whooping cough).

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Erythromycin often causes nausea and diarrhea, especially in children. Do not use for more than 2 weeks as it may cause jaundice.

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For newborns to 1 month old
Give 30 to 50 mg per kg each day, divided into 3 doses a day. Give for 7 to 10 days.
For an average-sized newborn of about 3 kg, each dose should be:
0.75 ml (this is a bit more than ⅛ teaspoon) of 250 mg/5 ml erythromycin syrup, OR
62 mg. (¼ of a 250 mg tablet) ground up in a little breast milk or water.
For breast infection (mastitis) in a breastfeeding mother
Give 250 to 500 mg (1 or 2 tablets of 250 mg), 4 times a day for 10 days.


Ceftriaxone is in the cephalosporin antibiotic family. Cephalosporins are antibiotics that work against many kinds of bacteria. They are often expensive and not widely available. However, they generally have fewer risks and side effects than many other antibiotics and can be useful in treating certain serious diseases, including sepsis and meningitis, and for infections resistant to penicillin. Only use ceftriaxone to treat the specific infections for which it is recommended in your area. This will help prevent resistance and keep this drug useful.

Ceftriaxone is especially useful for gonorrhea, including gonorrhea infection of the newborn’s eyes but otherwise should not be given to newborns under 1 week old and should be avoided in babies under 1 month old.


Do not give ceftriaxone to a baby less than 1 week old. Avoid in babies who were born early or especially small (if there is a chance that they may have been early). Do not give if there is jaundice.

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Ceftriaxone can only be given by injection in the thigh muscle or IV (in the vein). It can be painful to inject. Mix with 1% lidocaine if you know how.

For gonorrhea eye infection in the newborn 7 days or older
Inject 50 mg per kg, one time only. Do not give more than 125 mg.
For severe infection when other antibiotics are not available, in a baby or child older than 7 days
Inject 75 mg per kg, once a day for 7 to 10 days. So:
For a newborn of 3 kg, inject 225 mg once a day.
For an older baby of 6 kg, inject 450 mg once a day.

This page was updated:05 Jan 2024