6–14 Week Vaccines

Pentavalent Vaccine Side Effects in Babies

Fever, a sore swollen thigh and a grumpy, sleepy baby are the expected reactions to the 5-in-1 shot — they usually settle within a day or two.

🟢 Usually mild💉 Given: 6, 10 & 14 weeks⏳ Settles: 1–2 days⏱️ 7 min read🗓️ Updated 6 July 2026✅ 7 sources🩺 Medical review pending

Written and fact-checked by the ParentVibes editorial team against WHO, IAP, CDC and NHS immunisation guidance. Not yet reviewed by a named clinician.

Quick facts

Usually given: 6, 10 & 14 weeks, in the thigh
Protects against: 5 diseases in one shot
Typical reaction: Fever + sore, swollen thigh
Reaction starts: Within hours of the injection
Usually settles in: 1–2 days (up to 3)

The pentavalent vaccine is the workhorse of your baby's 6, 10 and 14 week visits — one injection into the thigh that guards against five serious infections: diphtheria, whooping cough, tetanus, Haemophilus influenzae type b (Hib) and hepatitis B. Rolling five vaccines into one means fewer needles for your baby, and it sits at the heart of India's National Immunization Schedule.

Because the version used in most Indian clinics contains whole-cell pertussis (the 'DTwP' component), pentavalent tends to cause more of a reaction than the gentler birth vaccines. A warm, grizzly baby with a tender thigh on vaccination evening is the rule rather than the exception here — and knowing that in advance turns an anxious night into an expected, manageable one.

What the pentavalent vaccine is

Pentavalent is an inactivated (non-live) combination vaccine — its full name is DTwP-HepB-Hib. It bundles the diphtheria, whole-cell pertussis and tetanus components (the classic DTwP) together with hepatitis B and Hib protection into one prefilled dose, given into the front-outer thigh muscle at 6, 10 and 14 weeks.

The whole-cell pertussis part is very good at building strong, lasting protection against whooping cough, but it is also the ingredient most responsible for the fever and local soreness families notice. This is a known trade-off — the reaction is a sign of a robust immune response, not of anything going wrong.

One shot, five diseases

Because the hepatitis B given here overlaps with the birth dose, and Hib and pertussis protection build over the three doses, completing all three visits on time matters — each dose strengthens the last.

Common pentavalent side effects

Most reactions appear within a few hours of the injection and centre on fever and the injected thigh. They are more noticeable than after the birth vaccines — and that is expected.

Fever

A raised temperature in the first 24 hours is one of the most common reactions to pentavalent. It is usually mild to moderate and settles within a day or so. A fever after this vaccine is expected and, on its own, is not a cause for alarm.

A sore, swollen, red thigh

The injection site often becomes tender, warm, red and a little swollen. The swelling can look surprisingly firm and lumpy, and your baby may cry when the leg is moved or during nappy changes — this settles over a few days.

Fussiness and crankiness

Many babies are unusually irritable, clingy or hard to please on vaccination evening. Extra holding, feeding and gentle rocking are the best comfort while it passes.

Sleepiness

It is common for babies to be drowsier than usual and to nap more in the day or two after the shot. A sleepy but rousable, feeding baby is behaving normally.

Reduced feeding

A temporary dip in appetite is common — your baby may take shorter or fewer feeds for a day. Offer feeds often; normal feeding usually returns within a day or two.

A small hard lump at the site

A firm, painless lump can linger under the skin at the injection spot for a week or two after the redness fades. As long as it is shrinking and not hot, it is harmless.

Ask about paracetamol

Because fever is so common with this vaccine, your paediatrician may advise paracetamol in the dose matched to your baby's weight. Follow their instructions exactly — never use aspirin for a child, and don't give ibuprofen to a baby under 3 months.

What's usually normal after pentavalent

The pentavalent reaction is stronger than the birth vaccines but follows a predictable path. These are all signs of a normal response:

A mild to moderate fever starting within a few hours and easing within a day or two.
A red, warm, swollen and tender thigh that looks worse before it looks better.
A cranky, clingy baby who wants more cuddles than usual on vaccination day.
Extra sleepiness and longer naps, with your baby still rousable for feeds.
Slightly reduced feeding for a day, returning to normal soon after.
A small firm lump at the site that slowly shrinks over a week or two.

Time after the shot	What you'll typically see
First few hours	Fussiness begins; thigh starts to feel sore
6–24 hours	Fever, redness and swelling at the site peak
1–2 days	Fever settles; fussiness and sleepiness ease
3–14 days	Redness fades; a small firm lump may linger, then goes

How long pentavalent side effects last

Fever: usually starts within hours and settles within 1–2 days.
Thigh soreness, redness and swelling: typically improve over 2–3 days.
Fussiness and sleepiness: usually gone by the second day.
Reduced feeding: normally back to normal within a day or two.
A small hard lump at the site: can take 1–2 weeks to fully disappear.

It repeats each dose

A reaction at the 6-week dose does not mean something is wrong — a similar fever and sore leg can follow the 10 and 14 week doses too. This is expected and safe; keep the schedule on track.

Home care after the pentavalent vaccine

The aim is simple comfort: ease the fever, soothe the leg, and keep feeds going.

Fever & comfort

Dress your baby in light clothing and keep the room comfortably cool — don't bundle a warm baby in blankets.
Offer feeds more often than usual; breast milk or formula also keeps your baby hydrated through a fever.
If your doctor has advised it, give paracetamol in the dose matched to your baby's weight — never aspirin, and no ibuprofen under 3 months.
Cuddles, skin-to-skin contact and gentle rocking genuinely help a fretful, feverish baby settle.

The sore thigh

Handle the leg gently during nappy changes and avoid pressing or rubbing the injection site.
A clean, cool (not icy) damp cloth held on the site for a few minutes can ease the soreness.
Gentle, natural movement of the leg is fine and helps — you don't need to keep it still.
Never massage the lump or apply oils, balms or hot compresses unless your doctor advises it.

Warning signs — see a doctor urgently

Everyday fever and fussiness are expected. These signs, however, need prompt medical attention:

Seek urgent medical care if your child has

A very high fever of 40°C (104°F) or above, or a fever that won't come down.
A fit or seizure — jerking, stiffening or staring with unresponsiveness (a febrile seizure is uncommon but frightening and needs review).
High-pitched, inconsolable crying that continues for more than 3 hours despite comforting.
A pale, floppy, limp or unusually unresponsive episode, or a baby who is very hard to wake.
Signs of a severe allergic reaction — difficulty breathing, swelling of the face or lips, or widespread hives, usually within minutes to an hour.
Injection-site swelling that spreads widely, becomes very hot and hard, or oozes pus.

Call your doctor immediately — or go straight to the nearest emergency department.

🩺 Find a paediatrician

If your baby has a seizure, is struggling to breathe, or becomes floppy and unresponsive, go to the nearest emergency department immediately — do not wait.

When to call your paediatrician

Not an emergency, but worth a call or a visit:

Fever that lasts beyond 48 hours or keeps returning after it seemed to settle.
The thigh swelling or lump grows, stays hot, or seems increasingly painful after a few days rather than easing.
Feeding stays noticeably reduced for more than a day, or wet nappies drop off.
Your baby remains very unsettled or 'not themselves' beyond the first day or two.
You're unsure whether what you're seeing is a normal reaction — a quick call for reassurance is always reasonable.

Frequently asked questions

Why does the pentavalent vaccine cause more fever than other vaccines?

The version used in most Indian clinics contains whole-cell pertussis (the DTwP part), which builds strong whooping-cough protection but also triggers more fever and soreness than gentler vaccines. A fever in the first day is expected — it shows the immune system responding, not that anything has gone wrong.

My baby's thigh is swollen and hard after the 5-in-1 shot. Is that normal?

Yes. A red, warm, swollen and firm thigh is one of the most common reactions and can look dramatic. It usually settles over 2–3 days. See a doctor if the swelling spreads widely, becomes very hot and hard, oozes pus, or your baby seems seriously unwell.

Can I give my baby paracetamol before the pentavalent vaccine?

Only if your paediatrician advises it. Because fever is common with this vaccine, some doctors recommend paracetamol in the dose matched to your baby's weight. Follow their instructions exactly — never give aspirin to a child, and do not give ibuprofen to a baby under 3 months.

My baby cried for hours after the injection. Should I worry?

Some crying and crankiness is expected on vaccination evening. But high-pitched, inconsolable crying that goes on for more than 3 hours despite comforting should be checked by a doctor, as should any fit, floppy episode or very high fever.

Will the same reaction happen at the next dose?

It can. A similar fever and sore leg may follow the 10 and 14 week doses. This is expected and safe, and is not a reason to skip or delay — completing all three doses on time gives your baby the fullest protection.

The vaccine is due but my baby has a mild cold. Can it still be given?

A mild cold without a significant fever is usually not a reason to postpone routine vaccines. Tell the vaccinator how your baby is, and they will decide — but minor sniffles rarely need the shot to be delayed.

Your next steps

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Related vaccine guides

DPT Vaccine side effects Rotavirus Vaccine side effects PCV (Pneumococcal Vaccine) side effects IPV (Injectable Polio Vaccine) side effects

→ See side effects for all childhood vaccines

Sources

Next review due: 6 January 2027.

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Medical disclaimer

This page is educational information about common vaccine reactions and is not a substitute for medical advice, diagnosis or treatment. Every child is different — always follow the guidance of your paediatrician or vaccination centre. If your child has trouble breathing, swelling of the face or throat, a fast heartbeat, hives all over, dizziness or weakness soon after a vaccine, or seems seriously unwell at any point, seek emergency medical care immediately. When in doubt, always get your child checked — it is never a waste of anyone's time.

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