Flip over a shampoo bottle and you are faced with a wall of unpronounceable names. Some of the "toxic ingredient" claims circulating online are overblown. Some are worth genuinely paying attention to. Very little of what you will read online tells you which is which.
Here is a clear breakdown of what to actually watch for on an Australian shampoo label — including where the evidence is strong, where it is unresolved, and where the internet has got ahead of itself.
First, the good news about Australian labels
This is the part most ingredient guides miss, because most of them are written for a US audience.
In Australia, cosmetic products sold to consumers must carry a full ingredient list, using standardised INCI names, in descending order of mass or volume. Ingredients present at under 1% can be listed in any order after that. This is required under the Cosmetics Information Standard, which the ACCC administers.
Separately, the chemicals themselves are assessed by AICIS — the Australian Industrial Chemicals Introduction Scheme, which replaced NICNAS in July 2020 under the Industrial Chemicals Act 2019. AICIS evaluates chemical safety before introduction. It does not, however, regulate cosmetic labelling or advertising. That sits with the ACCC.
Two practical consequences:
- You can actually check. Unlike in some markets, a full list is not optional. If a brand is vague about what is in the bottle, that is a choice, not a regulatory limitation.
- The order tells you a lot. An ingredient near the top is present in meaningful quantity. The same ingredient in the last three positions is at under 1%. "Contains argan oil" means very little if the argan oil is listed after the preservative.
The one significant gap is fragrance, which we will come to.
Sulphates (Sodium Lauryl Sulphate / Sodium Laureth Sulphate)
Sulphates are powerful cleansing agents, which is exactly the problem — they are often too effective. They strip the scalp's natural oils along with dirt and product build-up, which can leave hair dry, frizzy and, over time, more prone to damage. On colour-treated hair they are the single biggest cause of fast fade.
They are not "toxic" in the scare-headline sense. Sodium lauryl sulphate is a well-studied irritant at high concentration, not a systemic health risk. But for dry, colour-treated or sensitive scalps, this is the first ingredient worth cutting.
On SLES specifically: the ethoxylation process it goes through can leave trace 1,4-dioxane, which the International Agency for Research on Cancer classifies as Group 2B — possibly carcinogenic to humans. Reputable manufacturers vacuum-strip it out, and levels in finished products are regulated. The honest position is that this is a manufacturing-quality question you cannot resolve from the label, which is a reasonable argument for avoiding the ingredient class rather than trying to assess individual suppliers.
Methylisothiazolinone and Methylchloroisothiazolinone (MI / MCI)
This is the ingredient missing from almost every "avoid" list, and dermatologically it is the most defensible one on this page.
MI and MCI are preservatives that became widespread as brands moved away from parabens. The result was an increase in allergic contact dermatitis significant enough that dermatologists described it as an epidemic, and the American Contact Dermatitis Society named methylisothiazolinone its Contact Allergen of the Year in 2013.
The EU response was decisive: MI has been banned from leave-on cosmetics since 2017, and the permitted concentration in rinse-off products such as shampoo was cut from 100 ppm to 15 ppm.
Shampoo is a rinse-off product, which reduces but does not eliminate exposure — documented cases of allergic contact dermatitis from rinse-off products exist, and MI is volatile enough to cause airborne contact reactions in some people.
If your scalp itches, flakes or reddens and you cannot work out why, this is the first ingredient to look for. Watch for: Methylisothiazolinone, Methylchloroisothiazolinone, and the blend often listed as MCI/MI.
Formaldehyde and formaldehyde-releasing preservatives
Worth genuine caution, with an important piece of context.
Some preservatives do not contain formaldehyde directly but slowly release small amounts to keep a product microbe-free. Look for: DMDM Hydantoin, Quaternium-15, Imidazolidinyl Urea, Diazolidinyl Urea, and Bronopol(2-Bromo-2-Nitropropane-1,3-Diol).
Formaldehyde is classified by IARC as a Group 1 carcinogen. That classification is important to understand properly: it is based primarily on evidence from occupational inhalation exposure — industrial workers breathing formaldehyde over long periods — not on cosmetic use. Regulators cap the concentration permitted in cosmetics precisely because of that hazard profile.
The stronger everyday argument is simpler: formaldehyde is a recognised skin irritant and contact allergen, and Quaternium-15 in particular is a common cause of contact dermatitis. If you have sensitive skin or a known allergy, avoid the group.
Parabens (Methylparaben, Propylparaben, Butylparaben)
Genuinely one of the more debated ingredients in cosmetics, and worth being fair about.
Regulatory bodies including the EU's Scientific Committee on Consumer Safety and the US FDA have reviewed parabens repeatedly and continue to consider them safe within set limits. The study that started the public concern — a 2004 paper finding parabens in breast tissue samples — never established that parabens caused the tissue changes, and it has been widely misrepresented since.
That said, parabens can weakly mimic oestrogen, which is why the EU restricts the longer-chain ones such as butylparaben and propylparaben more tightly, and banned several others outright in 2014.
The honest summary: the evidence against parabens is better described as unresolved than proven. If you would rather not take the chance, that is a reasonable personal choice — just make it with the actual state of the science in front of you rather than a headline.
Phthalates
Used to make fragrance last longer, and classified as endocrine disruptors, with research linking exposure to hormonal and developmental effects.
The problem is disclosure. In many markets phthalates do not have to be individually named when they form part of a fragrance blend, because fragrance formulations are protected as trade secrets. Australia's full-ingredient-list requirement helps, but "parfum" or "fragrance" still functions as a single entry covering many components.
The only reliable ways to avoid them: choose products stating phthalate-free, or products scented with named essential oils rather than a generic fragrance blend.
Synthetic fragrance ("Fragrance" / "Parfum")
Following directly from the above — this single word is the biggest blind spot on any otherwise readable label. A generic fragrance listing can legally represent dozens of undisclosed components.
This is where phthalates, allergens and irritants most often sit. It is also the most common trigger in fragrance-related contact dermatitis, which is why dermatologists routinely recommend fragrance-free products for reactive skin.
A shampoo scented with named essential oils — lemon myrtle, lavender, rosemary — tells you exactly what is on your scalp. Note that essential oils are not automatically hypoallergenic; some, such as limonene and linalool, are recognised allergens in their own right and must be declared in some markets. But named is always more useful than unnamed.
Silicones (Dimethicone and related "-cone" / "-conol" ingredients)
Not a health hazard. A hair-quality one.
Silicones coat the hair shaft to create instant smoothness and shine. With repeat use they build into a film that blocks moisture from penetrating. Over time hair can look glossy on the surface but feel dry, dull or weighed down underneath.
There is a specific catch for colour-treated hair: removing silicone build-up usually requires a clarifying shampoo, and clarifying shampoos strip colour. You end up in a cycle where the product creating the problem requires the treatment that undoes your colour.
Phenoxyethanol
The most common paraben alternative, and generally considered lower-risk. It is permitted in Australia and the EU up to 1%.
It is still flagged in some assessments as a moderate concern for skin irritation and sensitivity, particularly at higher concentrations or on reactive skin. Not a panic ingredient — but worth knowing it is not automatically "safer" simply because it is marketed as a paraben alternative.
DEA compounds (Cocamide DEA, MEA, TEA)
Foam boosters and thickeners. Individually low-risk, but they can react with nitrosating agents in a formula to form nitrosamines, several of which IARC classifies as probably or possibly carcinogenic. IARC has separately classified cocamide DEA itself as Group 2B.
Not emergency-level, and easy to avoid — plant-based foam boosters do the same job.
Four more worth knowing about
- PEG compounds (PEG-40, PEG-100 and similar). Like SLES, these are ethoxylated and can carry trace 1,4-dioxane. Same manufacturing-quality caveat.
- Alcohol denat. / SD Alcohol high in the list. Drying on hair and scalp. Fatty alcohols — cetyl, cetearyl, stearyl — are entirely different and are conditioning, not drying. Do not confuse the two.
- Sodium chloride (salt), used as a cheap thickener. Harmless, but a sign of a thin formula bulked out, and it can accelerate fade on keratin-treated hair.
- Synthetic colours (CI numbers, FD&C or D&C dyes). Purely cosmetic — they colour the shampoo, not your hair. No benefit to you whatsoever, and a possible irritant.
How to read a shampoo label in thirty seconds
- Read the first five ingredients. After water, these are the bulk of the formula. If a sulphate is second, it is a sulphate shampoo regardless of the front-of-pack messaging.
- Scan for "parfum" or "fragrance." Present with no essential oils named? That is your biggest unknown.
- Check for the preservative. Every water-containing product needs one. What matters is which: look for MI/MCI and the formaldehyde releasers.
- Look for "-cone" and "-conol" endings. Silicones.
- Notice where the good stuff sits. Hero botanicals listed after the preservative are present at under 1% and are doing more for the marketing than for your hair.
The Pure Earth approach
Our natural shampoo is made without sulphates, silicones, parabens, phthalates, synthetic fragrance, phenoxyethanol, artificial colours, animal derivatives or formaldehyde releasers — using plant-derived cleansers and naturally derived preservation.
What we use instead is named on the label: Australian natives including lemon myrtle and emu apple, plus rosemary, in our Extra Hydrating range, and lavender and chamomile in our Extra Gentle formula. No fragrance catch-all, no guesswork.
It is made in Australia, vegan and cruelty-free, and packaged in infinitely recyclable aluminium rather than plastic.
Don't take our word for it — scan it
Everything above is a brand telling you about itself, which is exactly the sort of claim this article has been arguing you should check rather than accept.
So check it. Pure Earth holds an "Excellent" rating on Yuka, the independent ingredient-scanning app.
Two things make that worth something. First, brands cannot pay Yuka for a score — it is calculated from the ingredient list, not bought, and we have no say in the result. Second, the way the scoring works sets a genuinely high bar: Yuka assigns every ingredient a risk level, and a single moderate-risk ingredient caps a product at 49 out of 100, while a single high-risk ingredient caps it at 24. To land in the Excellent band of 75–100, every ingredient in the formula has to come back risk-free or low-risk.
Scan any bottle in your bathroom with it. That is a more useful exercise than reading another brand's marketing — including ours.
Worth knowing about the methodology: Yuka scores on ingredient hazard, not concentration, so it does not account for the dose an ingredient is used at. It is a fast, independent screen rather than a full toxicological assessment — useful for exactly what this article is about, which is reading a label quickly and knowing what to question.
Shop sulphate-free shampoo and conditioner → · Read our full ingredient list →
Frequently asked questions
Is sulphate-free shampoo actually better? For dry, curly, colour-treated or sensitive scalps, generally yes — it cleans without stripping natural oils. For very oily hair or heavy product build-up, sulphate-free shampoo may feel less effective at first, and it often lathers less. Lather is a marketing expectation, not a measure of cleaning.
Why does my hair feel strange after switching to natural shampoo? Most people go through a short adjustment period, typically two to six weeks, particularly when coming off silicone-heavy products. Your hair is shedding accumulated coating and your scalp is rebalancing oil production after being repeatedly stripped. It settles.
Which shampoo ingredient causes scalp irritation most often? Fragrance and the preservatives MI/MCI are the two most common culprits in contact dermatitis from hair products. If your scalp reacts and you cannot identify why, check for those first.
Does Australia regulate shampoo ingredients? Yes. Chemicals are assessed by AICIS under the Industrial Chemicals Act 2019, and consumer labelling — including the requirement for a full ingredient list in descending order of concentration — is administered by the ACCC under the Cosmetics Information Standard.
Are natural preservatives safe? Every water-based product needs preservation, or it grows bacteria and mould — an unpreserved shampoo is a genuine safety risk, not a purer one. The question is never whether a product is preserved, but which preservative system it uses.
What is a good Yuka score for shampoo? Yuka rates cosmetics from 0 to 100 based on ingredient risk: 75–100 is Excellent, 50–74 Good, 25–49 Poor, 0–24 Bad. The bands are not evenly weighted — one moderate-risk ingredient caps a product at 49, and one high-risk ingredient caps it at 24. So an Excellent score means every ingredient in the formula came back risk-free or low-risk. Pure Earth's haircare is rated Excellent.
Are essential oils safer than synthetic fragrance? More transparent, not automatically safer. Some essential oil components are recognised allergens. The advantage is that you can see exactly what is there and avoid a specific one if you react to it.
