Baby's 4-Month Checkup and Vaccines: What to Expect

16 October 2026

The 4-month well-child visit is your baby's second big round of vaccines, along with a check of growth, feeding, sleep and development. At this visit most babies receive the second doses of the vaccines they had at 2 months. Side effects are usually mild and short-lived, much like last time. This guide walks through what happens at the appointment, which vaccines are given, how to comfort your baby afterward, and when to call your pediatrician.

What Happens at the 4-Month Well-Child Visit?

The visit starts with measurements: weight, length and head circumference, plotted on your baby's growth chart so your pediatrician can see the trend since the last visit. A head-to-toe exam follows, including the heart, lungs, hips, eyes and skin, and a look at how your baby holds their head and moves their arms and legs. Expect questions about feeding, sleep, wet and dirty diapers, and how your baby is interacting with you. It is also a good time to review safe sleep, car seat use and what to expect over the next two months.

Which Vaccines Does a Baby Get at 4 Months?

Under the American Academy of Pediatrics (AAP) 2026 immunization schedule, babies usually receive their second doses of these vaccines at 4 months:

• DTaP, protecting against diphtheria, tetanus and whooping cough
• Hib, protecting against Haemophilus influenzae type b
• Polio (IPV)
• Pneumococcal conjugate vaccine (PCV)
• Rotavirus, given by mouth as drops rather than a shot

Several of these often come combined in one injection, so your baby may get fewer shots than the number of diseases covered. Some combination vaccines also include a dose of hepatitis B. Federal recommendations for a few childhood vaccines, including rotavirus, changed in 2026 and differ from the AAP schedule, so your pediatrician will go over exactly what is recommended for your baby and answer any questions. For the full picture by age, see our children's vaccine schedule.

Are 4-Month Vaccines Worse Than 2-Month Vaccines?

For most babies, no. Reactions after the 4-month shots tend to look a lot like reactions after the 2-month shots: some fussiness, extra sleepiness and a sore leg for a day or two. Some babies are a little fussier the second time and others barely notice. A strong reaction at 2 months does not mean the same will happen at 4 months, but do tell your pediatrician how your baby handled the last round so they can give you tailored advice. Our guide to side effects after the 2-month vaccines covers the same reactions in more detail.

Common Side Effects and How to Comfort Your Baby

The most common reactions in the first 24 to 48 hours are:

• Fussiness or more crying than usual
• Sleeping more than normal
• Redness, swelling or a small firm lump where the shot was given
• A low-grade fever
• Eating a little less for a feed or two

Comfort goes a long way. Offer feeds often, hold your baby skin to skin, and use a cool, clean, damp cloth on a sore spot. Dress your baby lightly and keep the rest of the day calm. At 4 months, acetaminophen can be used for discomfort or fever, but the dose depends on your baby's weight, so check with your pediatrician or pharmacist first. Ibuprofen is not for babies under 6 months. Giving medicine before the shots to prevent a fever is not recommended.

When to Call the Pediatrician After 4-Month Shots

Call your pediatrician if your baby:

• has a temperature of 104°F (40°C) or higher, or a fever that lasts more than 48 hours after the vaccines
• cries inconsolably for 3 hours or longer
• refuses several feeds in a row or has fewer wet diapers than usual
• has repeated forceful vomiting, bloody stool, or episodes of severe belly pain with pulling up of the legs, which can rarely follow the rotavirus vaccine
• has redness or swelling at the shot site that keeps spreading or gets worse after two days

Call 911 or go to the emergency room for trouble breathing, swelling of the face, lips or tongue, widespread hives, a seizure, or a baby who is limp or very hard to wake. For concerns that should not wait for a routine appointment, our same-day sick child visits are available.

Growth and Development Milestones Around 4 Months

Four months is a fun age. By now many babies:

• smile on their own to get your attention and may chuckle
• hold their head steady without support when held upright
• push up onto their elbows or forearms during tummy time
• bring their hands to their mouth and look at their hands with interest
• hold a toy when you place it in their hand
• make cooing sounds and turn toward your voice

Every baby develops at their own pace, so think of these as a guide rather than a test. If your baby does not seem to follow moving things with their eyes, does not hold their head steady, or does not smile at people, mention it at the visit. You can read more in our guide to child development milestones by age.

Feeding and Sleep at 4 Months

Breast milk or formula is still all your baby needs. The AAP recommends starting solid foods at about 6 months, and not before 4 months. Signs of readiness include good head control, sitting up with support, and showing interest in food. Never add cereal to a bottle, and skip water and juice for now. Many babies also go through a stretch of more frequent night waking around this age as their sleep patterns mature. Keep putting your baby to sleep on their back, on a firm flat surface with no pillows, bumpers or loose blankets, ideally in your room for the first months.

How to Prepare for the Appointment

A little preparation makes the visit smoother. Write down how your baby handled the 2-month shots and any questions about feeding, sleep or development. Dress your baby in clothes that make it easy to reach both thighs, where infant vaccines are usually given. Bring a favorite blanket or pacifier, plan to feed or hold your baby right after the shots, and keep the rest of the day light.

Frequently Asked Questions

Which vaccines does my baby get at 4 months?

Under the AAP 2026 schedule, the 4-month visit usually includes second doses of DTaP, Hib, polio, pneumococcal and rotavirus vaccines. Your pediatrician will confirm what is recommended for your baby.

Are side effects worse after the 4-month shots?

Usually not. Most babies react about the same as they did at 2 months, with mild fussiness, sleepiness or a sore leg for a day or two.

Can I give Tylenol before the 4-month vaccines?

Giving medicine ahead of time is not recommended. If your baby is uncomfortable or feverish afterward, ask your pediatrician for the right weight-based dose of acetaminophen.

What should my 4-month-old be doing?

Many 4-month-olds smile and coo, hold their head steady, push up during tummy time and bring their hands to their mouth. Babies vary, so share any concerns at the visit.

Can I start solid foods at 4 months?

The AAP recommends waiting until about 6 months and never starting before 4 months. Talk with your pediatrician about your baby's readiness signs first.

Talk to Your Pediatrician

The 4-month visit is a good chance to ask anything that has been on your mind. As a pediatrician in Christiansburg, VA, our team is here to keep your baby on track with checkups and vaccines. Request an appointment whenever you need us. This article is for general education and does not replace medical advice for your baby's individual needs.

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