NAMED FRAGRANCE ALLERGEN
Alpha-Isomethyl Ionone
- named fragrance allergen
A violet-like fragrance component named separately as a recognised allergen.
- products in our library
- 592
- of researched products
- 9%
- on the label, in our leave-ins
- usually #28
- most common in
- Leave-in
- in water
- Oil-soluble
At a glance
Four things worth knowing about how this ingredient behaves on hair.
How much of it is left on hair between washes.
What it takes to get it off the hair again.
How specifically the label has to name it.
Where it sits on the labels we have, in the category it appears in most.
| Property | Level | Out of |
|---|---|---|
| Buildup risk | Needs a cleanser | 4 of 5 |
| Rinse-out behaviour | Rinses with a cleanser | 2 of 5 |
| Declaration | Named allergen | 5 of 5 |
| Prominence | Secondary | 2 of 5 |
What it does for a formula
What Alpha-Isomethyl Ionone does
The general function first, then how the role changes by product type where we have researched it.
A declared blend: the individual components are not named unless rules require it.
EU rules require this one to be listed by name rather than inside "fragrance".
It takes a surfactant to remove, which matters on a low-detergent routine.
Charge
Charge is not recorded for this ingredient.
Solubility
Needs a surfactant to remove. On a low-detergent routine it can build up over time.
Where it appears
Where it appears
One row per product category in our library: how many products list it, what share of that category that is, and where it typically sits on the label.
| Product type | How common | Typical position on label ? |
|---|---|---|
Leave-in
89 products
|
secondary · #28 | |
Shampoo
79 products
|
secondary · #28 | |
Conditioner
58 products
|
secondary · #26 | |
Mask / treatment
46 products
|
secondary · #29 | |
Heat protectant
35 products
|
secondary · #23 | |
Finisher: oil
31 products
|
secondary · #17 | |
Styler: curl cream
30 products
|
secondary · #29 | |
Styler: paste
30 products
|
secondary · #20 | |
Styler: hairspray
29 products
|
secondary · #17 | |
Styler: gel
26 products
|
secondary · #21 |
14 more product types
| Product type | How common | Typical position on label ? |
|---|---|---|
Styler: mousse
23 products
|
secondary · #23 | |
Finisher: serum
18 products
|
secondary · #16 | |
Dry shampoo
17 products
|
secondary · #19 | |
Styler: volumizer
15 products
|
secondary · #27 | |
Styler: texture spray
14 products
|
secondary · #17 | |
Styler: smoothing cream
12 products
|
secondary · #32 | |
Scalp treatment
11 products
|
secondary · #31 | |
Finisher: shine spray
9 products
|
secondary · #16 | |
Finisher: anti frizz finish
6 products
|
secondary · #27 | |
Co-wash
4 products
|
secondary · #29 | |
Styler: lotion
4 products
|
secondary · #26 | |
Styler: refresh spray
3 products
|
secondary · #15 | |
Styler: edge control
2 products
|
secondary · #23 | |
Finisher: end oil
1 product
|
supporting · #5 |
| Product type | Products | Share of category | Median position | Earliest position | Band |
|---|---|---|---|---|---|
| Leave-in | 89 | 13% | 28 | 7 | secondary |
| Shampoo | 79 | 5% | 28 | 14 | secondary |
| Conditioner | 58 | 5% | 26 | 1 | secondary |
| Mask / treatment | 46 | 8% | 29 | 14 | secondary |
| Heat protectant | 35 | 17% | 23 | 12 | secondary |
| Finisher: oil | 31 | 11% | 17 | 9 | secondary |
| Styler: curl cream | 30 | 13% | 29 | 13 | secondary |
| Styler: paste | 30 | 15% | 20 | 11 | secondary |
| Styler: hairspray | 29 | 12% | 17 | 6 | secondary |
| Styler: gel | 26 | 10% | 21 | 13 | secondary |
| Styler: mousse | 23 | 11% | 23 | 14 | secondary |
| Finisher: serum | 18 | 13% | 16 | 8 | secondary |
| Dry shampoo | 17 | 13% | 19 | 9 | secondary |
| Styler: volumizer | 15 | 10% | 27 | 9 | secondary |
| Styler: texture spray | 14 | 14% | 17 | 8 | secondary |
| Styler: smoothing cream | 12 | 15% | 32 | 15 | secondary |
| Scalp treatment | 11 | 4% | 31 | 10 | secondary |
| Finisher: shine spray | 9 | 9% | 16 | 6 | secondary |
| Finisher: anti frizz finish | 6 | 19% | 27 | 7 | secondary |
| Co-wash | 4 | 4% | 29 | 23 | secondary |
| Styler: lotion | 4 | 11% | 26 | 13 | secondary |
| Styler: refresh spray | 3 | 9% | 15 | 14 | secondary |
| Styler: edge control | 2 | 5% | 23 | 15 | secondary |
| Finisher: end oil | 1 | 13% | 5 | 5 | supporting |
We have not researched differences by product type yet. The reading below comes from where it sits on the labels in our library.
Position footprint
Every listing in our library, by position on the label.
| Positions | Zone | Listings |
|---|---|---|
| 1-3 | Leading | 1 |
| 4-8 | Supporting | 10 |
| 9-15 | Secondary | 90 |
| 16-25 | Lower | 220 |
| 26+ | Trace | 271 |
How to read this
US labelling rules put ingredients above 1% in descending order of amount; below 1% they may be listed in any order.
So position tells you about relative amount only above that line, and we never convert a position into a percentage.
Who should pay attention
Formulation guidance for specific hair conditions, limited to the label positions where it applies. It is not a conclusion about any finished product, or about you.
One of the 26 scent components the EU requires to be named individually above a threshold. It is named because it is a known contact allergen, not because it is unusual.
Read from this ingredient’s chemical class. Where we have researched the ingredient itself, that reading replaces the class one.
Why it matters to shoppers
What seeing this ingredient tells you, what it does not, and the limits of our own method.
- a scented product
- scent components named individually
- something that lasts through the day
- an exact safety score (we do not publish one for any ingredient)
- how a finished product performs, which depends on the whole formula, not one line of it
- the exact percentage in a bottle, because label position never converts into a number
- a secondary fragrance, listed below the main ingredients in our leave-ins
- it was on the printed ingredient list of every product we counted (we read labels, not marketing copy)
- that the product will suit you if you react to scent
- that it is riskier than the unnamed components of a fragrance blend
- that a product is right or wrong for you
We do not publish safety scores or hazard grades. Where a regulator has published a restriction or a use condition, we state it and cite it; otherwise we describe what the ingredient does and stop.
Commonly paired with
The ingredients that most often appear alongside this one in our library. We leave out the near-universal ones, because they pair with everything and tell you nothing.
- Hexyl Cinnamal · 328
- Citronellol · 301
- Benzyl Salicylate · 223
- Benzyl Alcohol · 221
- Geraniol · 206
- Coumarin · 176
- Hydroxycitronellal · 174
- Ethylhexylglycerin · 174
- Cetrimonium Chloride · 154
- Propylene Glycol · 152
The number beside a name is how many products in our library list both.
These ingredients tend to appear together to give it a scent, carry the formula and let it dry, and soften the strand.
Found in these products
The most prominent placements first. The badge is the position on that product’s own ingredient list.
Schwarzkopf Professional · Conditioner
BC Bonacure Moisture Kick Conditioner
#1 on the label · $2.03/oz
Hask · Finisher
Repair Series Weightless Repair Oil Mist
#5 on the label · $3.17/oz
Dove · Styler
Gloss & Control Non-Aerosol Hairspray
#6 on the label · $0.86/oz
TRESemme · Finisher
Keratin Smooth Blowout Hair Shine Spray
#6 on the label · $1.83/oz
Marc Anthony · Leave-in
Maximum Moisture Hydra Lock Instant Moisture Recharge Hair Mist
#7 on the label · $3.06/oz
TRESemme · Finisher
Lamellar Gloss Hydrating and Detangling Cream Serum
#7 on the label · $1.31/oz
TRESemme · Finisher
Lamellar Shine Spray Gloss
#7 on the label · $1.23/oz
BioSilk · Finisher
Silk Therapy Original
#8 on the label · $6.59/oz
Redken · Styler
Root Tease Backcombing Texture Spray
#8 on the label · $3.28/oz
Suave · Styler
Max Hold Non-Aerosol Hairspray
#8 on the label · $0.36/oz
TRESemme · Finisher
Lamellar Gloss Finishing Oil
#8 on the label · $2.42/oz
Design Essentials · Finisher
Silk Essentials Thermal Strengthening Serum
#9 on the label · $5.63/oz
See all 592 products in the library that list Alpha-Isomethyl Ionone
Identity
What this entry is, and what our references call it.
Alpha-Isomethyl Ionone
- CAS 127-51-5
- PubChem 5372174
- fragrance
- alpha isomethyl ionone
- alpha-isomethyl ionone
- alpha-isomethyl-ionone
- alpha-isomethylionone
- alphaisomethyl ionone
For your hair?
Whether Alpha-Isomethyl Ionone matters for your hair depends on your hair.
592 products in our library list itWhat this ingredient does, and where it sits on the labels we have researched.
A verdict on any product that contains it, and never a safety grade.
We do not physically test your hair. Everything above comes from the ingredient lists in our library and from published references. The consultation is what turns it into a plan.
References
Sourced Backed by a manufacturer or regulatory source.
This ingredient
- Manufacturer or regulatory PubChem : Compound identity: CID 5372174, CAS 127-51-5, C14H22O · accessed 2026-08-28
How this page was made
- Every number above is counted from the ingredient lists in our own product library: 592 of 6816 researched products list this ingredient. Nothing on this page is written per ingredient.
- The dots are levels, not scores. Each one comes from what kind of ingredient it is (its chemical class, charge and solubility) or from where it sits on the labels we have.
- US labelling rules put ingredients above 1% in descending order of amount; below 1% they may be listed in any order. Position tells you about relative amount only above that line, and we never convert a position into a percentage.
- The prominence bands (leading, supporting, secondary) are the same ones the product pages use to read a single label, applied here to the median position across a category.
- We do not publish safety scores or hazard grades. Where a regulator has published a restriction or a use condition, we state it and cite it; otherwise we describe what the ingredient does and stop.
- Identifiers and references appear only when a published source is attached to this entry. Without one, we leave the row out rather than fill it in.
- This is cosmetic information, not medical advice, and nothing here diagnoses or treats a health condition.
- Entry last updated 2026-09-22. Product-page methodology: the product library.
