Tretorin: What's In It and How It Works

Tretorin is Nolla’s renewal nighttime formula. It contains two active ingredients working together: tretinoin to drive cell turnover and unclog follicles, and niacinamide to manage inflammation and protect the skin barrier during the adjustment period. If this is in your prescription, your clinician has assessed that your acne is driven significantly by blocked follicles and that your skin will benefit from a retinoid-based approach.

What’s In Tretorin

Tretinoin is a vitamin A derivative (retinoid) and one of the most clinically substantiated topical ingredients in dermatology. It works by binding to retinoid receptors in skin cells and accelerating the rate at which cells turn over. In acne terms, this prevents dead cells from accumulating inside the follicle and forming the blockages that bacteria feed on. Over time, it also stimulates collagen production in the dermis, which improves skin texture and reduces the appearance of post-acne scarring. Tretinoin is a prescription-only ingredient because its potency requires calibration to your skin.

Niacinamide (vitamin B3) plays a supporting role specifically designed around the challenges of starting a retinoid. Tretinoin is effective but it’s also irritating, particularly in the first few weeks. Niacinamide soothes active inflammation, reinforces the skin barrier (which tretinoin temporarily disrupts), and inhibits the transfer of melanin - the pigment responsible for post-acne dark marks - between skin cells. The result is that the adjustment process is more manageable, and the formula addresses pigmentation at the same time it’s addressing the acne.

What To Expect - And When

Weeks 1–3: Purging is real with tretinoin and should be expected. Because tretinoin accelerates cell turnover, congestion that was sitting beneath the skin surface gets pushed up faster than it would naturally - leading to a temporary increase in breakouts. This is not a sign the treatment is making things worse. It typically lasts two to four weeks. You may also experience dryness, peeling, and redness.

Weeks 4–6: Purging should begin to settle. New breakouts should be less frequent. The skin’s barrier is adjusting and irritation typically reduces during this window.

Weeks 8–12: Follicle clearance, reduction in active acne, and early improvements in texture and post-acne marks are all typical outcomes with consistent use in this timeframe. Tretinoin’s full effects on texture and collagen continue to develop beyond 12 weeks.

How To Use It

Tretorin is a nighttime formula - apply it in the evening after cleansing and before any moisturizer. Tretinoin is photosensitive and degrades in UV light, so nighttime application is both more effective and safer.

• SPF the next morning, every morning. Tretinoin makes your skin significantly more sensitive to UV damage. Skipping SPF while using a retinoid actively undoes the repair work happening overnight.
• Start slow if your skin is new to retinoids. If you experience significant irritation in the first week, try applying every other night for the first two weeks before moving to nightly use.
• Moisturize after application. Apply a non-comedogenic moisturizer after Tretinoin to reduce irritation and support overnight barrier repair.
• Don’t layer other actives in the same routine. No AHAs, BHAs, vitamin C, or additional retinoids in the same evening routine.
• Avoid during pregnancy. Retinoids are contraindicated in pregnancy. Flag any change in circumstances through the app immediately.

Who Tretorin Is Designed For

Tretinoin is most appropriate for acne driven by comedones (clogged pores, whiteheads, blackheads) and where skin texture and post-acne marks are also a concern. It requires patience - but tretinoin has a stronger long-term evidence base than almost any other topical acne treatment.

The Bottom Line

• Tretinoin accelerates cell turnover to clear follicle blockages; niacinamide manages inflammation and barrier disruption during the adjustment period
• Purging in weeks 1–3 is expected - it’s existing congestion surfacing faster, not the formula making acne worse
• Meaningful improvement typically appears at weeks 8–12; effects on texture and scarring continue beyond that
• Daily SPF the morning after every application is essential - tretinoin significantly increases UV sensitivity
• Consistency over time is what makes tretinoin work