Tretinoin is one of the most extensively studied topical treatments in dermatology. Starting it correctly — at the right strength, frequency, and with appropriate skin preparation — significantly affects both tolerability and long-term outcomes. This guide covers what to expect, how to manage the adjustment period, and when to contact your prescriber.

Tretinoin is a prescription-only medicine in the UK. This article is for educational purposes only and does not replace the advice of your prescribing clinician. Always follow your prescriber's specific instructions.

What is tretinoin and how does it work?

Tretinoin (all-trans retinoic acid) is a vitamin A derivative that binds directly to retinoic acid receptors in the skin. Unlike over-the-counter retinol, which requires two conversion steps before becoming active, tretinoin is already in its active form — which is why it acts faster and more potently.

Its primary mechanisms include accelerating epidermal cell turnover, stimulating collagen synthesis in the dermis, normalising follicular keratinisation (relevant to acne), and inhibiting melanogenesis (relevant to pigmentation). These mechanisms underpin its clinical use across acne, photoageing, hyperpigmentation, and melasma.

Before you start: preparing your skin

Two weeks before beginning tretinoin, simplify your routine. Remove exfoliating acids (AHAs, BHAs), vitamin C serums, benzoyl peroxide (unless co-prescribed), and any other active ingredients. Use only a gentle cleanser, a fragrance-free moisturiser, and a broad-spectrum SPF 50.

This allows the skin barrier to stabilise before tretinoin is introduced. Starting on a compromised barrier significantly increases the risk of excessive irritation and early discontinuation.

For guidance on how to reintroduce other actives once you are established on tretinoin, see our skincare layering guide.

Understanding tretinoin strengths

Tretinoin is available in three main strengths: 0.025%, 0.05%, and 0.1%. Your prescriber will determine the appropriate starting strength based on your skin type, the condition being treated, and your prior experience with retinoids. Most prescribers recommend beginning at 0.025% or 0.05% regardless of the target concern, as tolerance is built gradually.

For a detailed comparison of what each strength is typically used for and how to progress, see our guide to tretinoin 0.025% vs 0.05% vs 0.1%.

How to apply tretinoin: step by step

1. Cleanse with a gentle, non-active cleanser. Pat skin dry.
2. Wait 20–30 minutes. Skin must be completely dry before application. Applying to damp skin significantly increases penetration and irritation.
3. Protect sensitive areas. Apply a thin layer of a bland occlusive (e.g. Vaseline) to the corners of the nose, mouth, and under-eye area before applying tretinoin.
4. Apply a pea-sized amount to the entire face. Dot onto forehead, cheeks, nose, and chin, then spread gently. Avoid the eyelids, lips, and nostrils.
5. Wait 20–30 minutes (optional), then apply a generous layer of fragrance-free moisturiser.

Using more than a pea-sized amount does not improve results and increases irritation. Your prescriber may give specific guidance on quantity.

Buffering for sensitive skin

If your prescriber recommends a gentler introduction, apply moisturiser first, wait 20 minutes, then apply tretinoin over it. This reduces intensity and is a reasonable starting strategy for reactive skin, to be phased out as tolerance develops.

What to expect in the first 12 weeks

Weeks 1–2

Minimal irritation is typical. Skin may feel slightly tight or dry. Some users notice a subtle improvement in texture early on.

Weeks 3–6: the adjustment period

This is when most users experience dryness, flaking, redness, and increased sensitivity. A temporary increase in breakouts (the tretinoin purge) is common during this phase. For a full explanation of what the purge is, how long it lasts, and how to manage it, see our dedicated article on the tretinoin purge.

Weeks 6–12: stabilisation

Irritation typically begins to subside. Flaking reduces, skin starts to smooth, and purging slows. Your prescriber may advise gradually increasing application frequency during this phase if tolerance allows.

Week 12 onwards

Visible improvements in texture, tone, and clarity become more apparent. Acne, pigmentation, and fine lines typically show meaningful improvement by 3–6 months of consistent use.

Managing side effects

Dryness and flaking

Apply moisturiser generously and frequently. A hyaluronic acid serum underneath moisturiser can help. Do not use physical exfoliants to remove flakes — allow them to shed naturally. If dryness is severe, contact your prescriber about temporarily reducing application frequency.

Redness and sensitivity

Reduce application frequency temporarily if needed, with your prescriber's guidance. Buffering with moisturiser before tretinoin can help. Avoid other potential irritants — hot environments, exfoliating products, and harsh cleansers.

Stinging or burning

Ensure skin is completely dry before application and that you are not using too much product. Mild tingling can be normal; persistent burning, pain, or blistering is not — contact your prescriber promptly if this occurs.

Sun exposure and SPF

Tretinoin increases photosensitivity by thinning the stratum corneum and accelerating cell turnover. Daily broad-spectrum SPF 50 is essential throughout treatment — not just in summer. The idea that tretinoin should be paused during summer months is a common misconception. See our article on using tretinoin in summer for a full explanation.

When to contact your prescriber

Contact your prescribing clinician if you experience:

• Severe or persistent irritation that does not improve with reduced frequency
• Signs of allergic reaction (urticaria, swelling, difficulty breathing)
• Worsening acne after 12 weeks of consistent use
• New breakouts in areas where you do not typically break out, after 8+ weeks
• Blistering, severe peeling, or skin that feels burned
• Any uncertainty about whether to continue or adjust your treatment

Long-term use

Tretinoin is safe for long-term use under medical supervision. Once results are achieved, many prescribers recommend a maintenance frequency (typically 3–5 nights per week) rather than nightly use. Regular follow-ups allow your prescriber to monitor progress and adjust treatment as needed.

Frequently asked questions

How long does it take for tretinoin to work?

Improvements in skin texture and tone typically become noticeable within 8–12 weeks. Significant results for acne, pigmentation, and fine lines usually require 3–6 months of consistent use. Full benefits accumulate over 12+ months.

What is the tretinoin purge and how long does it last?

The purge is a temporary increase in breakouts caused by accelerated cell turnover bringing existing congestion to the surface faster. It typically begins within 2–6 weeks of starting tretinoin and resolves within 6–12 weeks. It occurs in areas where you normally break out. See our full guide to the tretinoin purge for more detail.

Can I use tretinoin every night from the start?

Most prescribers recommend starting at 2–3 nights per week to allow the skin to build tolerance, increasing frequency gradually over several weeks. Starting nightly immediately significantly increases the risk of excessive irritation and early discontinuation. Follow your prescriber's specific instructions.

What strength of tretinoin should I start with?

This is determined by your prescriber based on your skin type, the condition being treated, and your prior retinoid experience. Most users begin at 0.025% or 0.05%. See our tretinoin strength comparison for a detailed breakdown.

Can I use tretinoin if I have sensitive skin?

Yes, but a more cautious approach is needed — a lower starting strength, less frequent initial application, and robust barrier support. Buffering (applying moisturiser before tretinoin) can reduce initial irritation. Discuss the appropriate protocol with your prescriber.

Should I stop tretinoin in summer?

No. Stopping tretinoin in summer means losing months of progress unnecessarily. Tretinoin does increase photosensitivity, but this is managed by applying it at night and using broad-spectrum SPF 50 every morning — which should be part of any skincare routine regardless. See our article on tretinoin in summer for more detail.

Can tretinoin be used during pregnancy or breastfeeding?

No. Tretinoin is contraindicated during pregnancy and breastfeeding. If you become pregnant while using tretinoin, stop immediately and contact your healthcare provider. Effective contraception is essential during treatment.

Can I use other active ingredients alongside tretinoin?

During the first 12 weeks, it is generally advisable to avoid other actives — including AHAs, BHAs, and vitamin C — to minimise irritation and allow the skin to adjust. After this period, reintroduction should be gradual and guided by your prescriber. See our skincare layering guide for more detail.