Toxins and side effects

What’s really in a vaccine?

It makes sense to look closely at the medicines and injections we give our children.

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Most of us didn’t study chemistry at university, so it’s understandable that we’ve got questions for the scientists.

Some people are concerned about the ingredients in vaccines. Words like formaldehyde, mercury and aluminium can sound worrying.

These chemicals are toxic to the human body at high levels.

toddler looking through microscope


baby receiving vaccination

But the amounts of chemicals found in vaccines are actually tiny.

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And careful research has proven that these amounts don’t cause any harm to people, even small babies.

So what’s the truth about these chemicals?

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It might surprise you to learn that formaldehyde is produced naturally by the body. In fact, there is far more formaldehyde present in a newborn’s body than in a single dose of vaccine.

Aluminium is also a naturally-occurring element, found in plants, air, food and water. Babies always have a small, safe amount of aluminium in their bloodstreams (about 5 nanograms). The amount of aluminium in a vaccine is so small it doesn’t cause any noticeable increase in this base amount, even immediately after an injection.

In the past, the preservative thiomersal was commonly used in vaccinations. Thiomersal contains the safer ethyl mercury, not the potent methyl mercury that is the cause of mercury poisoning. But as a precaution, thiomersal was removed from all routine childhood vaccines in 2000.


The most common preservative used in vaccines now is a tiny amount of alcohol.

It’s easy to see how information about vaccine ingredients can be distorted, sparking confusion and fear.

While it makes sense to protect your family from toxic levels of chemicals, it’s reassuring to remember that vaccines contain tiny amounts, much smaller than we’d encounter routinely in our everyday lives.

father taking child's temperature

What about the side effects of vaccines?

Any medicine we take has the potential to cause side effects.

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Usually, the doctor or pharmacist will explain these. And when we weigh up the benefits of taking this medicine against the low risk of side effects, many of us choose to take what’s prescribed to get well.

We can apply the same approach to vaccines.

The common side effects of vaccines are mild and temporary.

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Common reactions, like a mild fever or a sore, red spot at the injection site, are well documented.

But what about the rare side effects? And how do they compare to the worst symptoms of the disease they aim to protect us from?

Let’s consider measles as an example.

About 0.003% of people who get a measles vaccine develop a blood disorder (thrombocytopenia) that disappears in one to six months.

It can also cause immediate anaphylaxis in 0.0001% of people. That’s the same likelihood as naturally conceiving quadruplets! Your doctor will ask you to remain at the surgery for 15 minutes after the vaccination. In the unlikely event that you experience this side effect, it will be treated with an injection that provides quick recovery and no long-term effects.

Cases of measles are now being recorded in growing numbers. So what happens if you actually contract measles?

About 0.1% of children with measles develop a brain infection. Of those, at least 1 in 10 will die, and many who survive it have permanent brain damage.

So what do all these numbers mean? Well, it means the risk of developing a brain infection after contracting measles is 1000 times more likely than the risk of anaphylaxis resulting from the immunisation.

Compare the risks of other diseases and their vaccines here.

As a community, we’ve experienced living under the constant threat of deadly infectious diseases. COVID-19 is just the most recent example. Are the risks worth taking?

Get the real truth and make an informed decision…

Get the hard facts about the risks


Is there research we can rely on?


Get the hard facts about sources

Who can you trust? 

What’s true and what isn’t?

A University of Queensland initiative

This website answers the questions parents ask about vaccines. It’s clear and
easy to read, without any jargon or bias.

The University of Queensland is a world-class research and teaching institution.

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