What we consider “fringe” or “mainstream” changes over time. That applies to health and medicine too.

For instance, massage was once considered a fringe therapy but in the 19th century it morphed into what we know today as physiotherapy.

Likewise, Swiss doctor Maximilian Bircher-Benner wasn’t taken seriously when he said we should eat oats and fruit for breakfast. But he was onto something: he invented muesli.

There has also been traffic in the other direction. Legitimate medical therapies have turned up in the weird health borderland of beauty and “wellness”.

When untrained or barely trained people use these therapies, they can do real harm.

Here are five examples of wellness trends that borrow from mainstream medicine.

1. Ozone therapy

Ozone (O₃) is a form of oxygen. Ordinary oxygen (O₂), sometimes with ozone added, can be applied to wounds via a bag or sealed chamber to help them heal. It does this by helping the body fight infection and form collagen.

But “ozone therapy” – the weird, unlicensed version – puts ozone, or ozone and oxygen, directly into the person’s body. It can go in via the lungs, or via intravenous injection, or it can be pumped into the rectum or vagina.

Practitioners claim it can reduce inflammation, or even treat cancer or HIV/AIDS, despite no evidence for such health benefits.

It can also cause fatal air embolisms – bubbles of gas in the bloodstream that can block blood flow to vital organs.

2. Vitamin drips

If you don’t get enough of a certain vitamin or mineral through your diet, you can take a supplement. But if that doesn’t work, in some cases, you might need to go to hospital or a doctor’s surgery to get a medically supervised infusion that’s delivered into the vein (an IV infusion).

For instance, iron infusions help people with serious iron deficiencies.

But celebrity endorsements have helped fuel the rise of “vitamin drips” at wellness centres and therapy lounges. These drips promise all sorts of outcomes, from boosting your immune system, to treating pain or depression.

IV needles in untrained hands can be dangerous. They can cause phlebitis (inflammation of the vein) and infiltration (when the IV fluid or medication leaks into the surrounding areas). They can also lead to infection.

And unlike therapeutic vitamin IV infusions administered in hospital, these non-traditional treatments are not regulated by Australia’s Therapeutic Goods Administration. So you might also not be getting the magic IV potion you’re paying for.

3. Botox

The bacterium Clostridium botulinum produces a neurotoxin – a poison that affects nerves. For decades, it’s been used therapeutically to treat excess sweating and migraine, among other conditions. Today, we call this neurotoxin Botox.

Since about the 1990s, health professionals have been injecting it into people’s faces to temporarily paralyse the muscles that cause wrinkles.

It’s legal, it’s a registered product, and in trained hands it’s safe to use.

But as of September 2 this year, it’s been wrapped in an extra layer of regulation.

People who deliver any non-surgical cosmetic procedures – including Botox – will now be required to demonstrate higher skill levels under tougher policies.

This comes after several cases where nurses allegedly imported injectables from overseas. But these products weren’t registered for use in Australia and may not have been safe to use.

4. Apheresis

Apheresis is the process of separating blood into its component parts by spinning it at high speed in a special machine.

Clinicians use this process to separate out and remove specific molecules or antibodies in some diseases – what’s called “selective apheresis”.

For example, if a person has very high cholesterol that doesn’t respond to normal treatments, they can undergo lipid apheresis to “wash out” harmful lipoproteins from their blood.

It’s easy to see how the idea of “washing” your blood could be misunderstood and misapplied.

English actor Orlando Bloom announced earlier this year that he’d undergone apheresis to remove microplastics from his blood.

Microplastics in the body are a cause for concern – but there’s no evidence to suggest apheresis can cleanse human blood of them.

5. Hyperbaric therapy

When a diver gets “the bends” from too much nitrogen forming in their body, they can be treated in a hyperbaric oxygen chamber, where they receive 100% oxygen in a pressurised chamber.

But hyperbaric therapy is also touted as a treatment for autism, Alzheimer’s disease, cancer, strokes, and post-traumatic stress disorder.

There isn’t enough good science to back up any of these claims. There also isn’t enough science to suggest it makes your skin look younger.

The key message?

The history of medicine is full of stories about when mainstream forms of medicine have harmed instead of healed.

Humans have also always wanted to manage their own health. This has been going on for centuries, with both risks and benefits.

But just because a therapy has been used in a hospital for one reason doesn’t necessarily mean it works in a wellness clinic for another.

People can be easily convinced by aggressively marketed wellness therapies, which can be magnified by social media and celebrity endorsements.

However these therapies can come with a lack of evidence to support their wider uses, and they may harm.

Caveat emptor – let the buyer beware.