Why is the pre-school arm swelling sometimes so large?

Repeated doses of the diphtheria and tetanus components can produce a bigger local reaction, so this booster often causes more swelling than the infant doses did. It is uncomfortable rather than dangerous and settles within a few days, but any spreading redness with fever should be seen by a doctor.

Is this the same as the six in one vaccine?

No. The six in one (Hexavalent) adds Hib and hepatitis B and is given to babies. The four in one is the pre-school booster and leaves those two out, because the infant doses already covered them.

Vaccinecombination

DTaP/IPV

The pre-school booster combining diphtheria, tetanus, whooping cough and polio.

Reviewed by TinyDose editorial teamLast reviewed June 2026

Also known as: Four in one pre-school booster · DTaP/IPV · Infanrix-IPV

Protects against

Diphtheria, Tetanus, Whooping cough, Polio

How given

Single injection in the upper arm.

Doses

A single pre-school booster, between three and six years depending on the country.

Reactions

Moderate

DTaP/IPV combines four vaccines in one injection and is used as the pre-school booster in the UK, Australia and the Philippines. In the UK it is known as the four in one booster and given at three years four months; Australia gives it at four years. It tops up the protection built in infancy, before a child starts school and mixes with many more children.

What it protects against

Disease

Diphtheria

A bacterial infection that can block breathing and damage the heart.

Learn about Diphtheria →Disease

Tetanus

A serious infection caused by bacteria entering through wounds.

Learn about Tetanus →Disease

Whooping cough

A highly contagious cough that is especially dangerous for young babies.

Learn about Whooping cough →Disease

Polio

A viral infection that can cause permanent paralysis in young children.

Learn about Polio →

When it's given

3 years 4 months · Booster

Ages follow India schedules. Your pediatrician may adjust timing for your child.

How it's given

Single injection in the upper arm. This vaccine covers multiple infections in a single dose, reducing the number of separate injections needed at each visit.

Side effects & safety

A sore or swollen arm is common and can look more dramatic than it is, sometimes covering a good part of the upper arm before settling over a few days. A mild fever can follow.

How babies usually reactModerate

A mild fever or fussiness is fairly common for a day or two. This is a sign the immune system is responding normally.

When to call your doctor: if fever exceeds 40°C, lasts more than 2 days, or your child seems unusually unwell.

Alternatives & related vaccines

DTaPProtects against diphtheria, tetanus and whooping cough.HexavalentA single shot protecting against six infections, including polio and hepatitis B.PentavalentA single shot protecting against five infections, including hepatitis B and Hib.

Common questions

Sources

The complete routine immunisation schedule · UK Health Security Agency, 2026.

Information on this page is compiled from authoritative public health sources and written in TinyDose's own voice. It is intended for general understanding only. Always follow your pediatrician's guidance.

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Other vaccines

BCG OPV IPV DTwP All vaccines →

From the blog

All guides →

This information is provided by TinyDose for general understanding only and is not medical advice. Vaccine names, ages and doses can vary by country, brand and individual circumstances. Always follow the guidance of your pediatrician or local health authority for your child’s vaccination schedule.