Baby sleep after vaccinations: sleepiness, fever and red flags

A sleepy or unsettled day or two is one of the most common reactions to baby vaccinations. The NHS MenB vaccine page lists feeling tired or irritable, a high temperature and soreness where the injection was given, and says these side effects usually get better within 1 or 2 days. Some babies nap more than usual; others fuss, feed more often and wake more at night.

Extra feeds, cuddles and a calm, flexible day usually help. Keep every sleep safe while your baby recovers, and know the few signs that are never "just the vaccine": a high temperature in a young baby, a weak or high-pitched cry, floppiness or being hard to wake, signs of a severe allergic reaction, or a seizure.

For schedules by country and the full list of side effects, see baby vaccinations.

Is it normal for babies to be sleepy or unsettled after vaccinations?

Yes. Each of these sources lists sleep-related changes among the common, mild reactions:

The NHS 6-in-1 vaccine page lists feeling tired, irritability, loss of appetite and a high temperature as common side effects. The CDC's information statement on a child's first vaccines says fussiness, feeling tired and loss of appetite sometimes happen after the DTaP vaccine, and lists fussiness and feeling tired after the pneumococcal vaccine too.

Australia's healthdirect guide to immunization for your child lists pain, redness or swelling at the injection site, mild fever and being unsettled. The Better Health Channel in Victoria, Australia, says babies may be unsettled or sleepy.

In practice, you might see longer naps or a baby who dozes off early in the evening. You might also see the opposite: short naps, a baby who wants to be held, or more night wakings because the injection site is sore.

How long does sleepiness after vaccines usually last?

Usually 1 to 2 days. The NHS says MenB side effects usually get better within 1 or 2 days, the CDC says mild reactions go away within a day or two, and Better Health says side effects usually last 1 to 2 days. Australia's healthdirect says most mild side effects last only a few days.

Some vaccines can cause a reaction later. The NHS MMRV vaccine page says a measles-like rash, feeling unwell and a high temperature usually appear about 6 to 10 days after vaccination, and that common side effects usually last 2 to 3 days. So if your toddler's sleep goes off about a week after their MMRV vaccine, the vaccine may be part of the picture. The fever rules below still apply.

Healthdirect also mentions a small, pea-sized lump (nodule) at the injection site that can last for weeks or sometimes months. It usually goes away on its own and shouldn't bother your baby.

If sleep is still unsettled after a few days, look for another cause, such as a cold, teething or a developmental change. See sleep when your baby is sick, teething and sleep and sleep regression ages.

How can I comfort my baby and keep sleep safe after vaccines?

1. Offer extra feeds. Australia's healthdirect suggests you keep breastfeeding and cuddle your baby. The NHS fever page says to give plenty of fluids and, if your baby is breastfed, to keep breastfeeding as normal. Formula-fed babies can have their usual feeds, offered more often if they want them.
2. Cuddle, talk and sing. Healthdirect suggests a gentle, soothing voice, singing and cuddles. The CDC says hugs, cuddles and soft whispers can help soothe older babies after a needle.
3. Ease a sore leg or arm. Healthdirect suggests pressing something cool on the injection site, and Better Health suggests a cold, wet cloth.
4. Dress them lightly. The NHS says not to cover a child with a high temperature in too many clothes or bedclothes, and not to undress them or sponge them down. Better Health says not to overdress a baby who is hot. The Royal Children's Hospital Melbourne fever fact sheet says not to give a cold bath or shower.
5. Keep every sleep safe. Put your baby on their back in their own crib or bassinet, with their head and face uncovered and nothing soft in the crib. Australia's Red Nose's six safe sleep recommendations in Australia include a safe sleeping environment night and day, and your baby's own sleep space in your room for at least the first 6 months.
6. Hold them safely. A sleepy baby who wants to be held is common after vaccines. Contact naps are fine while you're awake; if you start to feel drowsy, put your baby down in their crib. The NHS SIDS page says never to sleep on a sofa or in an armchair with your baby. See contact napping.
7. Check on them, including overnight. The NHS says to check on a child with a high temperature regularly, including during the night.
8. Go easy on the routine. Many families let naps run a little longer and keep the evening calm for a day or two, then go back to their usual rhythm once their baby seems themselves again.

Don't add blankets, wedges or pillows to help an unsettled baby sleep. The safe sleep rules don't change when your baby is unwell. See safe sleep.

Should I give acetaminophen after the MenB vaccine?

In the UK, yes. The NHS MenB vaccine page recommends child's acetaminophen after the MenB vaccinations at 8 weeks and 12 weeks, to help prevent or treat a high temperature. It says to give 3 doses:

• the first as soon as possible after the vaccination
• the second 4 to 6 hours later
• the third 4 to 6 hours after that

The NHS adds that you should leave at least 4 hours between doses and give no more than 4 doses in 24 hours.

Use the MenB schedule, not the packet, for these doses. The UK Health Security Agency's guide to acetaminophen after MenB says to use infant acetaminophen suspension 120 mg/5 mL and give 2.5 mL (60 mg) for each of the 3 doses, measured with a syringe or the 2.5 mL end of the spoon. It explains that this differs from the patient information leaflet in the pack, which applies to fevers at other times. Junior acetaminophen (6 plus, 250 mg/5 mL) is stronger and must not be used in babies. Babies born before 32 weeks need acetaminophen prescribed by their doctor according to their weight. If your baby is asleep when a later dose is due, the guide says not to wake them.

Australian advice also recommends acetaminophen with MenB, but the timing differs. Australia's healthdirect says a child under 2 having the MenB vaccine should have 3 doses of acetaminophen: the first 30 minutes before the vaccination or as soon as possible after, then 6 hours later, and again 6 hours after that, even without a fever. Follow the advice your vaccination provider gives you.

For other vaccines, routine acetaminophen isn't recommended. Australia's healthdirect says there's no recommendation to give it before every vaccination "just in case", and Better Health says routine use after vaccination isn't recommended. Acetaminophen is for pain or a fever that's making your baby miserable, not a sleep aid. The NHS fever page says not to give acetaminophen to a child under 2 months, or ibuprofen to a baby under 3 months or under 5 kg. See fever in babies.

What temperature after vaccines needs urgent help?

A raised temperature is a common side effect, but the age rules for fever still apply straight after vaccines.

The NHS urgent-help guide lists 38°C or higher under 3 months, and 39°C or higher at 3 to 6 months, among reasons to call an ambulance or go to A&E. Its longer list of serious signs leaves out babies who have had a vaccine in the past 2 days, and the NHS MenB and 6-in-1 pages ask for an urgent doctor appointment or a call to the NHS advice line instead. Our guides use the stricter tier for both ages, even within 2 days of vaccines: call 911 or go straight to the nearest emergency room.

Because a high temperature is a common side effect of the UK's 8-week MenB vaccine, ask at the appointment what to expect, so you're not caught off guard. The RCH says there's no need to treat a fever if your child is otherwise comfortable and drinking.

Is it OK to vaccinate if my baby is already sleeping badly or has a cold?

Usually, yes. Australia's healthdirect says a child with a minor illness and no fever can be safely vaccinated, but a major illness or a fever of 38.5°C or higher is a reason to reschedule. Poor sleep on its own isn't among the reasons Australia's healthdirect gives for rescheduling.

A few things can make the day easier:

• Wait at the clinic for at least 15 minutes after the vaccines, as Australia's healthdirect and Better Health advise.
• Bring what you need to feed and settle your baby straight afterwards.
• Keep the rest of the day quiet, with naps at home in the crib where you can.

When should I get help after vaccinations?

Severe allergic reactions are very rare and usually happen within minutes, the NHS says, which is one reason to wait at the clinic for at least 15 minutes. The CDC notes that one could still happen after you leave.

Call 911 now if your baby:

• has swelling of the lips, tongue or throat, trouble breathing or swallowing, wheezing or noisy breathing, or hives with any of these (the NHS anaphylaxis page also lists a child who is limp, floppy or not responding like they normally do)
• is floppy, much sleepier than usual, hard to wake or can't be woken, or is too sleepy to feed
• has a weak, high-pitched or continuous cry; the CDC lists non-stop crying for 3 hours or more after DTaP as a less common, more serious reaction
• has a seizure (fit), however short
• is under 3 months with a temperature of 38°C or higher, or 3 to 6 months with 39°C or higher
• has blue, gray, pale or blotchy skin, lips or tongue, is breathing very fast or is struggling to breathe
• has a rash that doesn't fade when you press a glass on it, or hasn't had a pee for 12 hours

Get medical help today (a same-day doctor or your pediatrician's after-hours nurse line) if your baby:

• still has a high temperature more than 48 hours after a MenB vaccine
• is refusing feeds or feeding much less than usual, or has fewer wet diapers, but is alert
• in the week after a rotavirus dose, keeps being sick, has a swollen or painful tummy, or has blood in their poop or poop like redcurrant jelly; the NHS rotavirus vaccine page explains the very small risk of a bowel blockage. Call 911 if they're vomiting with a swollen, hard tummy, have more than a streak of blood in their poop, or are pale, floppy or very unwell
• seems unwell and you're worried

Talk to your doctor or pediatrician if a lump at the injection site worries you, sleep hasn't settled a few days after vaccines with no other signs, or you have questions about the next visit.

What's worth noting after vaccinations?

Write down the date and time of the vaccines, any temperature with the time you took it, any doses of acetaminophen with the time, and how your baby is feeding, sleeping and wetting diapers. A day or two of notes makes it easy to see whether things are settling, avoids doubling up on medicine, and gives a doctor a clear picture if you need one.