Retinol guide - how it works, side effects and correct use | Nordic Skin College

Few skincare ingredients are as well documented as retinol - and few are as misunderstood. Some swear by it as the closest thing we have to a miracle worker against fine lines and blemish-prone skin. Others have tried it once, ended up with red, flaking skin and shelved it for good.

The truth lies somewhere in between. Retinol works, and that is documented in decades of research. But it only works if you use it correctly: with the right strength, the right build-up and the right patience. Most bad retinol experiences are not down to the ingredient, but to the way it was introduced.

In this guide you get the full picture: how retinol works, what side effects to expect - including the notorious “retinol purge” - and how to build up without damaging your skin barrier along the way.

What is retinol?

Retinol is a form of vitamin A that is converted into retinoic acid in the skin. Retinoic acid binds to receptors in the skin cells and influences how the cells renew themselves: it increases cell turnover in the skin’s outer layers and stimulates collagen production in the dermis. Over time, the result is smoother, firmer and more even skin.

Retinol belongs to the retinoid family, which ranges from mild over-the-counter forms to prescription medication. What they all have in common is that they must be converted into retinoic acid before they take effect - and the fewer conversion steps, the stronger the effect and the greater the risk of irritation.

The retinoid forms in brief

• Retinyl esters (e.g. retinyl palmitate): The mildest form with the most conversion steps. Gentle, but also modest in effect.
• Retinol: The classic over-the-counter form and the best documented without a prescription. A good balance between effect and tolerance.
• Retinal (retinaldehyde): Only one conversion step away from retinoic acid. Faster results than retinol, but typically also more expensive.
• Retinoic acid (tretinoin): Prescription-only in Denmark and reserved for medical treatment, typically of acne. Prescribed by a doctor or dermatologist.

What can retinol be used for?

Retinol addresses several skin concerns at the same time, because it works with the skin’s fundamental renewal process rather than a single symptom.

The best-documented effects:

• Fine lines and wrinkles: Increased collagen production gives the skin more firmness and smooths fine lines over time.
• Blemish-prone skin and acne: The increased cell turnover prevents dead skin cells from clogging the pores - one of the central mechanisms behind breakouts.
• Pigmentation changes: Retinol speeds up the replacement of pigmented cells and gradually evens out skin tone.
• Rough texture and enlarged pores: A smoother surface and less visible pores, because the pores are kept clear of accumulated sebum and cells.

If you want to see how retinol works alongside niacinamide, vitamin C and acids in a complete routine, we have covered it in our guide to skincare ingredients that work.

The retinol purge - when the skin gets worse before it gets better

The retinol purge is a temporary worsening of the skin during the first weeks of retinol use. Because retinol accelerates cell turnover, impurities that were already sitting beneath the surface are pushed up faster. This can show as more breakouts, small bumps and flaking skin - typically in weeks 2 to 6.

The important thing to understand: a purge does not create new problems, it accelerates the ones that were already on the way. That is why it primarily affects the areas where you normally get breakouts.

How to tell a purge from genuine irritation:

• Purge: Breakouts in your usual problem areas, subsiding gradually after 4-6 weeks, with the skin otherwise calm.
• Irritation or reaction: Redness, stinging, a burning sensation or breakouts in places you never normally get them. Does not subside - or gets worse.

With a purge, the answer is to stay the course and possibly reduce the frequency slightly. With genuine irritation, you should take a break, rebuild the barrier with moisture and ceramides, and start again at a slower pace. If you are in doubt, or if the worsening lasts more than 6-8 weeks, seek guidance from a professional or your doctor.

How to build up correctly

Building up gradually is the whole secret behind a good retinol experience. The skin needs time to develop tolerance, and that happens gradually over weeks, not days.

A well-proven build-up plan:

1. Weeks 1-2: Start with a low concentration (0.3-0.5%) twice a week, always in the evening.
2. Weeks 3-4: Increase to three times a week if the skin is calm.
3. Weeks 5-8: Gradually increase to every other evening, then every evening if the skin allows it.
4. After that: Only consider a higher concentration once your skin has been stable on daily use for a couple of months.

Three techniques that make the build-up easier:

• The sandwich method: Apply moisturiser, then retinol, then moisturiser again. This slows absorption and reduces irritation - good for sensitive skin.
• A pea-sized amount: More product does not give better results, only more irritation. A pea-sized amount covers the entire face.
• Wait for dry skin: Apply retinol to completely dry skin. Damp skin increases absorption and with it the risk of stinging.

And the most important rule of them all: use sunscreen every morning. Retinol makes the skin more sensitive to light, and without SPF the sun undermines exactly the results you are working towards.

Side effects - what is normal, and what is not?

Mild side effects at the start are normal and to be expected: slight dryness, fine flaking, a little tightness and a touch of redness. This is called retinisation and is a sign that the skin is adapting. It typically subsides within 2-4 weeks.

What is not normal: severe stinging, burning redness, swelling or an eczema-like rash. Here you should stop, let the skin settle, and see a doctor if the reaction is severe or does not subside.

Avoid combining retinol with AHA/BHA acids on the same evening, and hold back on other exfoliation during the build-up period. Niacinamide, hyaluronic acid and ceramides, on the other hand, are good companions that support the barrier along the way.

Who should be careful with retinol?

Retinol is not the right choice for everyone - and for some, the timing is wrong.

• Pregnant and breastfeeding women: Prescription retinoids are advised against during pregnancy, and as a general rule it is also recommended to pause cosmetic retinol. Talk to your doctor, and choose alternatives such as peptides in the meantime.
• Very sensitive or reactive skin: Start extra low and slow, or consider milder alternatives first. With skin conditions such as rosacea or eczema, you should clarify your skincare with a doctor or dermatologist before introducing retinol.
• Skin with a damaged barrier: First rebuild the barrier with moisture and ceramides for a few weeks. Retinol on top of a weakened barrier is almost guaranteed to cause irritation.
• Before waxing and certain treatments: Pause retinol for a few days before waxing and stronger exfoliating treatments, and always mention your retinol use to your therapist.

Realistic expectations and timeline

Retinol rewards patience. The first visible improvements in the skin’s glow and texture typically come after 8-12 weeks of consistent use, while the effect on fine lines and pigmentation takes 3-6 months or more. It is not a quick fix, it is a long-term investment in the skin’s renewal.

Consistency beats strength every time. A low concentration used faithfully for a year gives markedly better results than a high concentration you give up on after three weeks because your skin protested.

Unsure whether retinol is right for you?

The right skincare starts with understanding your skin. At Nordic Skin College’s student clinic at Kongens Nytorv, you can book a personal skin analysis and consultation, where we assess your skin type and condition and give you concrete guidance - including whether retinol fits into your routine, and how to get off to a good start.

And if you dream of being able to advise on the skin’s biology at a professional level yourself, take a look at our cosmetology and skin therapy programme. Here you learn not just to use the ingredients, but to understand why they work.