Tretinoin
Prescription retinoic acid — the most potent topical retinoid, a near-guaranteed irritant, and strictly off-limits in pregnancy
INCITretinoin
- Category
- Retinoid
- Risk level
- medium
- What it is
- Active retinoic acid — binds retinoid receptors directly, no conversion needed; far more potent than OTC retinoids
- Reaction type
- Irritation ("retinoid dermatitis"), dose-dependent — not an allergy
- Prescription-only
- Requires a prescription in essentially all markets (e.g. Retin-A)
- Pregnancy
- Teratogenic class — strictly avoided in pregnancy and breastfeeding
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Possible reactions
- Significant dryness and flaking ("retinoid dermatitis")
- Redness and erythema at the application site
- Burning and stinging
- Increased UV sensitivity
- Eczema flares in atopic-prone skin
What is tretinoin?
Tretinoin (all-trans retinoic acid; brand Retin-A) is the active form of vitamin A that skin cells use directly, with no conversion needed. While OTC retinoids (retinol, retinaldehyde, retinyl palmitate) must be converted in the skin, tretinoin binds retinoid receptors immediately — which is why it's dramatically more potent, and why it's prescription-only in essentially every market.
It's one of the most evidence-backed ingredients in dermatology, prescribed for acne, photoaging, fine lines, and hyperpigmentation, and it's a component of the classic "Kligman" melasma combination (tretinoin + hydroquinone + a mild steroid).
Why it irritates — and why that's not allergy
Tretinoin's irritation is inherent to its mechanism, not a formulation flaw. Accelerating cell turnover transiently disrupts the barrier, producing "retinoid dermatitis":
- Dryness and flaking as turnover outpaces smooth shedding (worst in weeks 4–8)
- Redness from mild inflammation and increased vascularity
- Burning/stinging as the disrupted barrier lowers the irritation threshold
- Photosensitivity — sunscreen becomes mandatory
- Eczema flares — the barrier disruption can set off atopic dermatitis, so it's generally avoided during active eczema
This is irritation, not allergy, and it's dose-dependent — higher strength (0.1% vs 0.025%) and daily use cause more. "Low and slow" (0.025%, two nights a week, building up) is standard practice.
- Pregnancy: tretinoin is teratogenic — strictly avoided in pregnancy and breastfeeding. 2) Unregulated combination creams: the tretinoin + hydroquinone + steroid "triple combination" is powerful but, when used unsupervised or bought from unregulated sources, causes steroid-thinned skin, rebound pigmentation, and damage. Use only what a dermatologist prescribes and monitors.
How to use it well (under a prescriber)
- Start low and slow — 0.025%, two nights a week, increasing as tolerated.
- Dry skin, at night — apply ~15 minutes after washing.
- Sandwich method for sensitive/eczema-prone skin (moisturiser → tretinoin → moisturiser).
- Daily SPF — non-negotiable.
- Don't combine with benzoyl peroxide in the same application.
Gentler alternatives
- Milder retinoid: adapalene (often OTC) or OTC retinol/retinaldehyde.
- Eczema-prone or sensitive: azelaic acid (acne + pigment, far gentler).
- Pregnancy: bakuchiol, azelaic acid, niacinamide.
The bottom line
Tretinoin is the most powerful topical retinoid — and its irritation is the price of that potency, not an allergy. Used carefully under a dermatologist (low-and-slow, buffered, with sunscreen) it's transformative; the absolute lines are no pregnancy and no unregulated combination creams.
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