Newborns need very few things: milk, a small number of protective medical treatments given at birth, and in some cases a daily vitamin supplement. That’s essentially the complete list for the first several months of life. What they don’t need is just as important to understand, since giving a newborn the wrong thing, even plain water, can be dangerous.
Breast Milk or Formula Only
For the first six months, the only food or drink a newborn needs is breast milk, infant formula, or a combination of both. Nothing else should go into their stomach. Breast milk adapts its composition over the first days and weeks to match a baby’s nutritional needs, starting with colostrum, a thick, yellowish fluid packed with antibodies and nutrients. Formula provides a standardized alternative with added iron (typically 12 mg per liter) to prevent anemia.
A newborn’s stomach is remarkably small, which is why frequent, small feedings are normal. On day one, the stomach holds about 5 to 7 milliliters, roughly one teaspoon. By day three, capacity grows to about 22 to 27 milliliters (4 to 5 teaspoons). By the end of the first week, a baby can take in 45 to 60 milliliters (1.5 to 2 ounces) per feeding. At one month, that increases to 80 to 150 milliliters (3 to 5 ounces) per feeding. These volumes explain why newborns eat so often, typically 8 to 12 times in 24 hours, and why spitting up after overfeeding is common.
Vitamin K at Birth
Within the first six hours after birth, newborns receive a single injection of vitamin K. Babies are born with very low levels of this vitamin, which is essential for blood clotting. Without it, they’re at risk for vitamin K deficiency bleeding, a condition that can cause dangerous internal bleeding, including in the brain. There are three forms: an early type within the first 24 hours, a classic type between days 2 and 7, and a late-onset type that can appear anywhere from 2 weeks to 6 months of age. The standard dose is 0.5 mg for babies weighing under about 3.3 pounds and 1.0 mg for larger newborns. A single injection is highly effective at preventing all three types.
Hepatitis B Vaccine
The first vaccine a newborn receives is for hepatitis B, given within 24 hours of birth for babies at a healthy birth weight. Babies born to mothers who test positive for hepatitis B receive the vaccine along with an additional protective treatment within 12 hours of birth. This is the beginning of a three-dose series that continues at 1 to 2 months and again at 6 to 18 months. The birth dose is important because hepatitis B transmitted from mother to child during delivery can lead to chronic liver disease, and the virus can spread through household contact in early life.
Vitamin D Drops for Breastfed Babies
Babies who are exclusively or partially breastfed need 400 IU of vitamin D every day, starting shortly after birth. Breast milk, despite its many advantages, contains very little vitamin D, and newborns don’t get enough sun exposure to make their own. Liquid vitamin D supplements designed for infants come with a dropper and are given directly into the mouth or mixed into a bottle of expressed milk. Formula-fed babies who consistently drink at least 32 ounces of formula per day generally get enough vitamin D from the formula itself, though most newborns aren’t consuming that volume yet.
Why You Should Never Give a Newborn Water
Plain water is dangerous for babies under six months. Their kidneys are too immature to process excess water, and even small amounts can dilute the sodium in their blood to dangerously low levels, a condition called hyponatremia. Symptoms include irritability, unusual sleepiness, low body temperature, swelling, and in severe cases, seizures. The rapid drop in sodium causes brain cells to swell, which is what makes this condition a medical emergency. Breast milk and formula already contain all the water a newborn needs, even in hot weather.
Medications to Avoid
Most over-the-counter medications are off-limits for newborns. Ibuprofen is not recommended for any infant under six months because of risks to the kidneys and gastrointestinal tract. Acetaminophen (the active ingredient in Tylenol) should not be given to newborns without specific guidance from a pediatrician, as dosing depends on exact weight and age, and the liquid concentrations vary between products in ways that can cause confusion and accidental overdose.
One product that is generally considered safe is simethicone gas drops. Because simethicone isn’t absorbed into the bloodstream, it poses essentially no systemic risk. However, clinical studies have not found it effective for treating colic, so while it won’t harm your baby, it may not help much either.
Pacifiers
Pacifiers are fine for newborns, but if you’re breastfeeding, both the American Academy of Pediatrics and the American Academy of Family Physicians recommend waiting until breastfeeding is well established before introducing one. This typically means waiting a few weeks until your baby has a reliable latch and your milk supply is consistent. For formula-fed babies, a pacifier can be offered from the start. Pacifier use during sleep is actually associated with a reduced risk of sudden infant death syndrome.
Eye Ointment at Birth
In many hospitals, a thin line of antibiotic ointment is applied to a newborn’s eyes within the first 24 hours. This prevents a type of eye infection that can be transmitted during delivery, most seriously from gonorrhea, which can cause rapid corneal scarring and vision loss. Chlamydia, which causes milder but still concerning eye infections, accounts for up to 40% of these cases. Whether this treatment is routine or selective depends on your region and local laws. In some areas, it’s required by law for all newborns. In others, it’s recommended primarily when certain risk factors are present.
What a Newborn Actually Needs From You
Beyond feeding and these few medical basics, newborns need skin-to-skin contact, warmth, sleep, and responsive care. They don’t need supplemental vitamins beyond vitamin D (if breastfed), herbal remedies, gripe water, cereal in their bottle, or juice. Keeping the list short protects their immature digestive system and kidneys. If you’re ever unsure whether something is safe to give your newborn, the simplest rule holds: if it isn’t breast milk, formula, or something specifically recommended by your pediatrician, it can wait.