What Retinol Really Does: a Scientific Guide to Strengths, Side Effects and Resuts

Retinol (indeed, more accurately the retinoids) are a group of ingredients found in many skincare products that manage to be both wildly famous but deeply misunderstood.  Everyone’s heard of retinol, most people have dabbled, yet the myths swirl as thickly as the promise: it will either transform your skin into something poreless and incandescent, or leave you red, flaky and deeply regretful.

The truth of course is less dramatic and far more interesting.  Retinol a molecule with decades of clinical evidence behind it, not a passing fad like many ‘hero’ ingredients that come and go on TikTok; it works not by sanding away the surface like an exfoliant, but by changing the way your skin behaves at a much deeper cellular level.  That’s why dermatologists call it the gold standard of anti-ageing ingredients.  But (as with all powerfult things) the details matter: the form, the strength and how you introduce it will dictate whether you emerge glowing or grumpy.  Think of it as a long-term relationship; get it right, and your skin will thank you for years.

What is retinol and how does it work in skincare?

Retinol is part of the retinoid family (retinoids), derived from vitamin A (retinoic acid) and is one of the most scientifically validated ingredients we have in skincare.  When applied topically, retinol itself is not directly active as the skin must convert it first into retinaldehyde and then into retinoic acid (2 conversion steps), which is the biologically active form.  Retinoic acid is a fat soluble vitamin which can then diffuse across the cell membrane and bind to ‘retinoic acid receptors’ within the nucleus of skin cells.   This then causes switching on and off the expression of certain genes that regulate cell behaviour.  With retinoids in the skin, this leads to a faster turnover of keratinocytes in the epidermis, which sheds away dull, pigmented surface cells more efficiently and it stimulates fibroblasts in the dermis to increase production of collagen and elastin.  Another effect is on melanocyte cells (pigment cells) where retinoids act as tyrosinase inhibitors - meaning they interrupt the production of melanin in the skin, reducing the appearance of pigmentation.  The various effects of retinoids explain why retinol (or retinoids) are so useful in skincare - they improve both superficial tone and deeper structural integrity of the skin at multiple layers.

What are the benefits of using a retinol cream?

As a result of the cellular effects I mentioned, the benefits are extensive and wide ranging.  At the surface level retinol helps to smooth rough texture, refine pores and even out irregular pigmentation caused by UV damage or hormonal fluctuations.  Deeper within the skin retinolstimulates collagen and elastin production by activating genes in the fibroblast cells which reduce the appearance of fine lines and early wrinkles and can help to restore firmness that naturally reduces with age.  It also regulates how skin cells shed within the hair follicle, which is why it is effective against comedonal acne and can reduce breakouts.  Over the longer term regular retinoid use leaves the skin clearer, smoother and more resilient to environmental stressors.

When should you start using a retinol cream?

The right time to introduce retinol depends on individual skin concerns rather than age alone, though generally I recommend the mid-to-late twenties as a sensible starting point as a preventative measure.  By this stage, collagen production has already begun its natural decline and many people notice the first subtle signs of ageing or pigment change, particularly in paler skin types.  Those who suffer from acne may benefit from using retinolearlier under medical supervision, as it is an extremely effective therapy for managing both active breakouts and the post-inflammatory pigmentation that can follow.  Conversely, for people in their forties and beyond who have never used it, retinol is no less effective it can still bring significant improvements, particularly when introduced gradually and supported with a strong barrier focused routine.

What strength retinol should you use?

Strength is an area where caution and individualisation are important.  Strength is one of the most misunderstood aspects of retinoid use.  What matters is not only the percentage printed on the label, but also the form of vitamin A being used and how many conversion steps it must take before becoming biologically active as retinoic acid.  An additional consideration is the process of retinization (the period of adjustment when the skin first encounters retinoids and responds with dryness, peeling, redness or sensitivity as cell turnover accelerates and the barrier adapts).  This phase can last several weeks and is often the point at which people give up, mistaking it for an allergic reaction rather than a predictable biological response.  The choice of strength therefore has to balance efficacy with tolerability - if it’s too weak, and results will be slow; too strong, and the irritation of retinization can make it impossible to continue.  The goal is always to find a formulation and concentration that can be used consistently.

Retinyl esters (e.g. retinyl palmitate which often used in introductory products) need three conversions and are therefore the weakest and most gentle. Retinol, the most common form in over-the-counter (OTC) products, requires two conversions before becoming active as mentioned above, making it moderately effective but still well tolerated by most skin types.  Retinaldehyde sits just one step away from retinoic acid, meaning it is significantly stronger than retinol at the same percentage, though also more likely to cause irritation if introduced too quickly.  At the far end of the spectrum is tretinoin (retinoic acid itself), available only on prescription in the U.K., which acts immediately without conversion and is correspondingly powerful, but also prone to side effects if the skin is not acclimatised.

Because of this hierarchy, percentages are not directly comparable across the different forms. A cream containing 0.1% retinaldehyde, for example, is far stronger in practice than a 0.1% retinol formulation.  For beginners, I usually recommend starting with a low-strength retinol, often between 0.1% and 0.3%, used only a few nights a week at first.  As the skin develops tolerance, this can be increased to 0.5% or even 1% if required.  Those with acne or more significant photo-damage may benefit from retinaldehyde or prescription retinoic acid, but these are best introduced with medical guidance.  Ultimately, the best strength is the one you can use consistently over months and years, because the cumulative effect of steady use is far more valuable than chasing high concentrations that your skin cannot comfortably tolerate.

This being said, newer molecules like Granactive Retinoid (hydroxypinacolone retinoate, HPR) offer something unique to avoid the retinization effects.  Found in my Good Night cream at 0.2% and my new Stellar Eye Cream at a slightly lower but no less important strength, it binds directly to the skin’s retinoid receptors without needing conversion, so in effect it delivers the potency of a retinaldehyde-level system but with dramatically less irritation.  What makes my Good Night cream unusual is that the retinoid isn’t working in isolation as it’s combined with niacinamide, an Azelaic acid derivative, PHAs, peptides and humectants to further reduce the retinization effects.  Together, these actives buffer the potential for irritation, reduce redness, reinforce the barrier and even aid penetration, meaning the skin can tolerate a strength of retinoid that would normally be considered ‘advanced’ from the outset.  This allows people to access the benefits of a high-performing retinoid (improved tone, reduced pigmentation, refined pores and collagen stimulation) without going through the uncomfortable phase of peeling, redness and sensitivity.  The end result is that you can start strong and stay consistent, which is the single most important factor in achieving results with retinoids.

How often should you apply

Frequency of application depends on both the strength of the formulation and your skin’s tolerance.  A gentle introduction might mean using a retinol cream twice weekly at first, then moving to alternate nights, and eventually to nightly application if the skin allows.  Retinolworks by stimulating a biological process that is ongoing, so more is not necessarily better; the goal is steady, regular use rather than aggressive dosing.  Many people find that their sweet spot is somewhere between three and five nights per week, combined with other active ingredients on the alternate days.

How long does it take to see results?

Like any skincare ingredient, patience is required as retinol works by changing cellular function rather than masking imperfections.  On average you may notice an improvement and refinement of texture within four to six weeks, but deeper benefits such as improved pigmentation and visible reduction of fine lines typically take three to six months of consistent use.  Collagen remodelling is a slow biological process and the most dramatic improvements are often seen after a year or more of regular use.  It’s important to view retinol as more of a long-term investment rather than a quick fix in your skin’s health.

What are the side effects and how do you avoid them?

As mentioned The most common side effects are dryness, redness, flaking and sometimes mild burning or stinging, particularly when first starting (the ‘retinization’ period’.  These are primarily caused by the accelerated rate of cell turnover, which temporarily disrupts the skin barrier.  To avoid this, the strategy is to start low and go slow: begin with a low concentration, limit frequency at first, and always pair with barrier-supportive products such as hydrating serums and moisturisers rich in ceramides or hyaluronic acid (these are pre-emptively included in my Good Night cream to automatically mitigate the retinization effects of the strong retinoid it contains!).Applying retinol on top of a thin layer of moisturiser, often called ‘sandwiching’, can also help to reduce irritation without significantly compromising efficacy. Daily sunscreen is a non-negotiable, as retinol makes the skin more sensitive to UV radiation.

Can retinol help with acne, dark spots, wrinkles or fine lines?

Retinol is one of the rare ingredients that is effective across multiple seemingly unrelated skin concerns.  For acne, it keeps the follicular opening clear of dead skin cells and reduces inflammation making it particularly helpful for blackheads and whiteheads.  For hyperpigmentation/dark spots, retinol regulates melanocyte activity by inhibiting the enzyme tyrosinase, which decreases melanin production, it also speeds up shedding of pigmented keratinocytes, leading to a gradual fading of all types of hyperpigmentation.  Wrinkles and fine lines are improved through stimulation of new collagen production and increased dermal thickness.  This breadth of action is why retinol is often described as a ‘universal corrective’.

How should you incorporate it into your routine?

Some retinoids are inactivated by UV light so they are usually best used at night, unless your product says it is one that isn’t.  The best way to introduce retinol is in the evening, on clean, dry skin, either alone (if it’s compounded with some hydrating ingredients) or followed by a nourishing moisturiser.  Because of its irritant potential, it should not be layered indiscriminately with other strong actives such as alpha-hydroxy acids unless the skin is tolerant or used to this.  A practical routine is to use retinol on one night for the first week, two or three nights per week for the second and third week, alternating with nights after that and eventually titrating to every night.  As mentioned, my Good Night is designed with other ingredients that reduce the necessity for this build up period, so in most it can be used every night immediately without worry.  In the morning, antioxidants such as vitamin C and always a high factor broad spectrum sunscreen will help to reinforce and protect the improvements that retinol is driving.

Can Retinol be used in eye creams?

Dark circles and sallowness around the eyes are notoriously difficult to treat because they are driven by several factors at once (pigment overproduction, sluggish circulation, thinning skin and loss of collagen support).  A standard retinol eye cream may address collagen but often at the expense of irritation (particularly in those with sensitive undereye skin) which may even worsens pigmentation and redness in this delicate zone.  Having experienced this with other retinoid eye creams, when I was developing my new Stellar eye cream, I looked for an alternative solution.  For this we chose Granactive Retinoid (HPR), the retinoid I have in my Good Night cream.  With this I wanted to harness the full corrective benefits of a high-performing retinoid (i.e. boosting collagen, regulating melanin activity and smoothing fine lines) while avoiding the inflammatory retinization response that undermines progress.  Paired with tetrahexyldecyl ascorbate (a lipid-soluble stablised form of vitamin C) and vitamin E, not only does it tackle oxidative stress but it has a potent effect on pigmentation in this area.   I’ve also added peptides and antioxidants to support microcirculation and barrier resilience.  The result is an eye treatment that provides these benefits but without the irritation or flaking that a less advanced retinoid would risk.

What ingredients does retinol pair well with?

Retinol pairs particularly well with hydrating and barrier-restoring anti-inflammatory ingredients, which help to mitigate its drying effects (again, my Good Night is unique in that it is a strong retinoid compounded with a number of other ingredients that reduce the risk of retinization).   Hyaluronic acid, Niacinamide, Azelaic acid, glycerin, squalane and ceramides are excellent companions.  Niacinamide in particular is a synergistic partner as it helps to reduce redness and strengthen the barrier, allowing skin to tolerate retinol more easily.  In the morning, vitamin C works well in complement, tackling oxidative stress and hyperpigmentation while retinol works overnight on cellular turnover and hyperpigmentation. 

What should be avoided are overly harsh combinations, such as using strong alpha hydroxy acids, salicylic acid or benzoyl peroxide alongside retinol, which can tip the balance from effective treatment to unnecessary irritation, particularly for new starters.

Final thoughts

Retinoids have earned their place as the backbone of intelligent skincare over many years due to the way they change skin behaviour over the long term. They coax sluggish cells into renewing more efficiently, remind fibroblasts how to make collagen and persuade melanocytes to be a little less overenthusiastic with pigment production. The problem, historically, has been that this sort of re-education often comes with a period of rebellion: the infamous retinization phase, when your face feels tight, flaky and slightly betrayed. Many abandon ship here, assuming they’ve developed an allergy or that retinoids are simply ‘not for them’. In reality, it’s a predictable, if deeply unglamorous, adjustment phase.

The newer generation of retinoid formulations show us that this purgatory isn’t inevitable.  Pairing potent vitamin A derivatives with ingredients that soothe, hydrate and stabilise the barrier, helps (in contemporary formulations) to achieve all of the cellular benefits without the irritation. This was the thinking behind my Good Night cream, which combines a direct-acting retinoid with niacinamide, azelaic acid and PHAs, and behind Stellar Eye Cream, which takes the same science and applies it to the most delicate area of all.  The principle is simple: strength doesn’t have to mean suffering.

If you’re considering adding a retinoid into your routine, the best place to start is with a formulation that respects your skin’s limits but still gives it something to work with.  Retinoids are a marathon, not a sprint and their true brilliance lies in what they do slowly, consistently, year after year.  Explore Good Night  and Stellar Eye Cream to see how retinoids can fit into your daily routine safely and effectively.

References

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Fisher, G.J., Datta, S.C., Talwar, H.S., Wang, Z.Q., Varani, J., Kang, S. and Voorhees, J.J. (1996) ‘Molecular basis of sun-induced premature skin ageing and retinoid antagonism’, Nature, 379(6563), pp. 335–339. Available at: https://www.nature.com/articles/379335a0 

Griffiths, C.E.M., Kang, S., Ellis, C.N., Kim, K.J., Finkel, L.J., Ortiz Ferrer, L.C., White, G.M., Hamilton, T.A. and Voorhees, J.J. (1995) ‘Two concentrations of topical tretinoin (retinoic acid) cause similar improvement of photoaging but different degrees of irritation: a double-blind, vehicle-controlled comparison of 0.1% and 0.025% tretinoin creams’, Archives of Dermatology, 131(9), pp. 1037–1044. Available at: https://pubmed.ncbi.nlm.nih.gov/7544967/ 

Kruger, L., Bambino, K., Schmalenberg, K. and Santhanam, U. (2025) ‘Efficacy of topical hydroxypinacolone retinoate-peptide product versus fractional CO₂ laser in facial ageing’, Journal of Cosmetic Dermatology, 24(1), pp. e1–e12. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC11743323/ 

Mukherjee, S., Date, A., Patravale, V., Korting, H.C., Roeder, A. and Weindl, G. (2006) ‘Retinoids in the treatment of skin aging: an overview of clinical efficacy and safety’, Clinical Interventions in Aging, 1(4), pp. 327–348. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC2699641/