Ingredient glossary
Methylisothiazolinone
On your shelf ✓What Methylisothiazolinone does for your skin, who it suits, and what to watch for.
INCI: Methylisothiazolinone · Also: MI
In short: Methylisothiazolinone delivers preservation, suits most skin types, and the evidence behind it is strong. One thing to know: can irritate, ease in slowly.
- What it does
- Preservation
- Best for
- Most skin types
- Watch out
- Can irritate, ease in slowly
- Evidence
- Strong
The molecule
The Glow take
Quiet, essential, and nothing to fear.
Methylisothiazolinone keeps a product safe to use from the first pump to the last, at tiny amounts. Not something you pay a premium for.
— Maya
What it does
- preservation
strong evidenceEpidemiologic data from large patch-test series show methylisothiazolinone sensitization rates reaching six to seven percent with facial and hand dermatitis from cosmetics and paints prompting regulatory restriction.
Who it's for, and who should skip it
Tends to suit
- all
Approach with care
- very sensitive
- eczema
- formaldehyde allergy
- Clogs poresLow
- Irritation riskHigh
How it fits each skin type
- DrySuits
- CombinationSuits
- OilySuits
- SensitiveTake care
Take extra care if any of these apply to you: eczema, formaldehyde allergy.
Where it fits in your routine
Plays well with
- alternative preservatives
Methylisothiazolinone, answered
Is Methylisothiazolinone safe during pregnancy?
Yes. Methylisothiazolinone is considered safe to use during pregnancy and breastfeeding. As with anything, if you are unsure it is worth a quick word with your doctor or midwife.
Who should avoid Methylisothiazolinone?
Approach Methylisothiazolinone with care if any of these apply to you: very sensitive, eczema, and formaldehyde allergy. Its irritation risk is high, so introduce it slowly and patch test first.
What concentration of Methylisothiazolinone actually works?
Its concentration is rarely printed on the label, so use the ingredient list as your clue: near the top third it is likely doing real work, near the bottom it is more of a sprinkle.
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