The Definitive Guide to Retinoids

Retinoids are the most researched and effective group of ingredients in skincare. They range from gentle over-the-counter serums, creams or gels to potent prescription products. The reason retinoids are so popular is because of their broad range of actions including treating acne, fading hyperpigmentation and softening the fine lines and texture changes of ageing skin. The only catch is that there are so many different types of retinoids and they vary enormously in strength. In fact, choosing the wrong one for your skin is all too common and usually the reason people either see no results or give up due to irritation. This guide explains what retinoids are, how they work and their uses. We compare the different types of retinoids in terms of strength and what they treat. Learn how to choose between them and how to get prescription retinoids in the UK.

What are Retinoids?

Retinoids are a family of compounds derived from vitamin A. They all do broadly the same job in the skin, but they differ in potency and how many steps it takes them to work. This affects their effectiveness, side effect profile and whether you need a prescription. It helps to split retinoids into two groups:

• Over-the-counter retinoids: These are ones can buy without a prescription. They include the retinyl esters (such as retinyl palmitate), retinol and retinaldehyde. You can easily find them as serums, creams, gels and sometimes even toners.
• Prescription retinoids: These are more potent compounds that you can only access by prescription from a doctor or other prescriber. Topical prescription retinoids include tretinoin (the topical gold standard), adapalene, tazarotene and aklief. They normally come in cream or gel formulas. The only oral retinoid for skincare is isotretinoin which is available by prescription for severe acne.

One thing to clarify is that all too often when people say “retinoid” they often mean the prescription kind. When they say “retinol” they usually mean the milder over-the-counter kind. However, this isn’t actually the case. Retinol is just the basic form of Vitamin A and is the most commonly available over-the-counter. All retinoids are derivatives of Vitamin A. So everything else that isn’t Retinol is a retinoid.

How Do Retinoids Work for Skin?

Every retinoid ultimately works by turning into the same thing; retinoic acid (aka tretinoin). This is the only form the skin can actually use directly. Retinoic acid binds to receptors in your skin cells and changes how they behave. It speeds up skin cell turnover, stimulates collagen production and helps unclog pores. This is what makes the whole family effective across acne, pigmentation and ageing.

The difference between the retinoids comes down to how far each one sits from that active form. The weaker, over-the-counter retinoids have to be converted by the skin in a series of steps before they can work. Each step loses some potency along the way, which is why a retinyl ester (three steps away) is far weaker than retinaldehyde (one step away). Prescription tretinoin skips the queue entirely, because it is already retinoic acid. Adapalene and tazarotene are synthetic retinoids that also bind the receptors directly without needing conversion. This is the single most useful thing to understand about retinoids. The fewer conversion steps, the more potent and faster-acting the retinoid. However, it also makes it more likely to irritate the skin.

The Retinoid Strength Ladder

The retinoid conversion pathway runs in a fixed order. Retinyl esters convert to retinol, retinol converts to retinaldehyde and retinaldehyde converts to retinoic acid. Because potency tracks so closely with how close each retinoid is to retinoic acid, the family forms a clear ladder from gentlest to strongest. The strength tiers (from lowest to highest) are:

• Retinyl esters (gentlest): Over-the-counter. These include retinyl palmitate, retinyl acetate and retinyl propionate. They are the most stable and best tolerated but the weakest. This is because they sit three conversion steps from the active form. Roughly speaking, 1% retinyl palmitate is about equivalent to 0.2% retinol.
• Retinol: Over-the-counter and the most widely used and studied over-the-counter retinoid. It sits two steps from retinoic acid, so it is a sensible starting point for most people new to retinoids. Strengths typically range from 0.025% up to 1%.
• Retinaldehyde (retinal): Over-the-counter and the most potent retinoid you can buy without a prescription. It is only one conversion step away from retinoic acid, which makes it stronger than retinol but better tolerated than tretinoin.
• Adapalene: This is a synthetic retinoid that binds the retinoic acid receptors directly. It is best known for treating acne and is often better tolerated than tretinoin, which makes it a good option for sensitive skin.
• Tretinoin (the benchmark): As pure retinoic acid, this needs no conversion and has over forty years of clinical evidence behind it for acne and photoageing. It is the standard against which every other retinoid is measured and our tretinoin guide covers it in full.
• Tazarotene (strongest topical): Prescription only and the most potent topical retinoid, roughly two to five times stronger than tretinoin. It is highly effective but carries the highest irritation risk. This is why it is used selectively.

Aklief is also a newer prescription retinoid which probably sits somehwere between adapalene and tretinoin. It is the only topical retinoid licensed for acne use on the body. Sitting outside this topical ladder is isotretinoin (the active in Accutane and Roaccutane). It is a prescription oral retinoid reserved for severe or treatment-resistant acne. Isotretinoin works throughout the body rather than just on the skin and has a number of serious possible side effects. It requires close monitoring throughout treatment.

What Do Retinoids Treat?

The reason retinoids are so widely prescribed is because they increase turn-over of skin cells which stimulates collagen building, smooths texture and unclogs pores. This mechanism of action can help address several of the most common skin concerns at once. Retinoids are useful treatments for:

• Acne: Retinoids unclog pores and reduce inflammation. This clears existing breakouts and prevents new ones. Topical retinoids are a first-line acne treatment whilst oral isotretinoin is reserved for severe cases.
• Hyperpigmentation & melasma: By speeding up cell turnover, retinoids fade hyperpigmentation, sun damage, melasma and post-inflammatory marks. They are often combined with pigment suppressors like hydroquinone for stubborn hyperpigmentation.
• Fine lines, wrinkles & skin ageing: Retinoids stimulate collagen, which softens fine lines and wrinkles and improves the firmness of ageing skin.
• Skin texture & tone: Even outside a specific condition, regular use refines pores, smooths roughness and gives skin a brighter more even appearance.
• Hair & beard growth (as an adjunct): Topical tretinoin is sometimes added to hair loss and beard formulas. This is not a standalone treatment but can help improve how well actives like minoxidil work. We cover this in more detail in our post on tretinoin for hair growth.

At City Skin Clinic, retinoids (and tretinoin in particular) are among the ingredients we prescribe most often. They form the backbone of many of our custom acne, hyperpigmentation, melasma and anti-ageing treatments.

Which Retinoid is Right for You?

With so many options, the right retinoid depends on three things. These are your skin’s sensitivity, the concern you are treating and your goals. As a general approach these are our top tips for choosing which retinoid to start on:

• If you are new to retinoids or have sensitive skin: Start low on the ladder. An over-the-counter retinol, retinyl ester ore retinaldehyde (if you want something stronger but still gentle), lets your skin build tolerance. Our post on retinoids for sensitive skin goes into this.
• If your main concern is acne: A prescription retinoid is usually more effective for moderate to severe acne. Adapalene is well tolerated and a common starting point, with tretinoin and tazarotene for more stubborn cases.
• If your main concern is ageing or hyperpigmentation: Tretinoin has the strongest evidence, which is why it is the benchmark. However, many people (especially with sensitive skin) often work up to it from a gentler retinoid.
• If you cannot tolerate retinoids at all: Bakuchiol is a plant-derived alternative that can help with general skin brightening and smoothing (for more check out our post on bakuchiol versus retinol). There are also other retinoid-free routes to anti-ageing and for treating acne without retinoids.

The most common mistake is jumping straight to the strongest retinoid available. A retinoid you can actually tolerate and use consistently will always beat a stronger one that irritates the skin. This can cause skin barrier damage, post-inflammatory hyperpigmentation and even drive you to give up.

How to Use Retinoids & the Retinisation Period

Retinoids reward patience and consistency and they punish impatience with irritation. Whichever one you use, the principles are the same. Start on the lowest strength that makes sense for your skin, apply it only two or three times a week at first, and build up the frequency as your skin adjusts. Use a pea-sized amount for the whole face at night, and always follow with a daily broad-spectrum sunscreen. This is because all retinoids make the skin more sensitive to UV damage.

The first few weeks are where most people struggle. As the retinoid speeds up cell turnover, it can trigger a period of dryness, redness, flaking and sometimes a temporary increase in breakouts. This adjustment period is called retinisation and the breakout part is skin purging. These are common things people can encounter and not a sign that the treatment is failing. This period usually settles within 4 to 6 weeks, and it is worth knowing how to tell purging from a genuine reaction. Supporting your skin barrier with a good moisturiser through this phase makes a real difference, and some people prefer to apply moisturiser before the retinoid to buffer it and reduce irritation. If you are still struggling with adapting after a couple of months, our post on why your retinoid might not be working covers the usual reasons.

Also, a word on combining retinoids with other actives. Retinoids pair well with some ingredients and clash with others, so it is worth knowing what to mix and what to avoid before layering them with acids or other treatments.

Retinoid Side Effects & Safety

Retinoids are powerful, and most people experience some side effects, especially early on. The good news is that the common ones are manageable and tend to ease as the skin builds tolerance. The typical side effects are:

• Skin irritation: Redness, dryness, peeling and stinging are the most common effects particularly during retinisation. They are usually worse with the stronger retinoids and settle with a gentle routine and a good moisturiser.
• Sun sensitivity: All retinoids make the skin more vulnerable to UV damage. This is why daily sunscreen is non-negotiable.
• Purging: A temporary increase in breakouts in the first few weeks as underlying spots surface faster.
• Allergic reactions: Rare but possible, and more serious. Patch test any new product and contact your prescriber if you suspect an allergy.

There is also a persistent myth worth addressing. The strength of a retinoid does not determine its results so much as your ability to use it consistently. This is also why retinol was the subject of new EU concentration limits rather than an outright ban.

Who Cannot Use Retinoids?

Generally speaking, retinoids suit most people with proper and approriate use. However, as with anything in life, they’re not for everyone. Below are some of the situations where you should either avoid or be more cautious:

• Pregnancy & breastfeeding: Retinoids are not recommended in pregnancy or for anyone trying to conceive, because of potential risks to the baby. This applies most strictly to oral isotretinoin, which is strongly teratogenic, but you should also not use any topical retinoids (even the weakest ones) as a precaution. It is best to avoid retinoids whilst breastfeeding too. Our pregnancy skincare guidance covers safer alternatives.
• Very sensitive skin, eczema or rosacea: People with eczema or rosacea may find retinoids too irritating. They can still be use them but the type, strength and frequency need careful calibration.
• Sunburnt or broken skin: Never apply a retinoid to sunburnt skin, open wounds or an active eczema flare.
• Anyone on interacting medication: Some medicines and treatments, including certain in-clinic procedures like lasers or microneedling may require stopping retinoids for a period. Always tell your prescriber what else you use.

How to Get Prescription Retinoids in the UK

Over-the-counter retinoids like retinyl esters, retinol and retinaldehyde are freely available in cosmetic products throughout the UK. However, prescription retinoids are a different matter. You can only get them through a doctor or other qualified prescriber who has assessed your skin and decided they are safe and appropriate for you. Any website or clinic selling prescription retinoids without a consultation is not a legitimate source. Historically this meant an in-person dermatology appointment. Now you can also get prescription retinoids like tretinoin online in the UK through a number of telehealth clinics which offer online consultations and treatment if appropriate.

At City Skin Clinic, we believe skincare should be personal. We use topical retinoids like tretinoin alongside other actives where appropriate following an online consultation with one of our doctors. They will review your skin, concerns and medical history to create a bespoke treatment plan suitable for your needs. You can read more about our treatments for acne, hyperpigmentation, melasma and skin ageing, or book a consultation to start your journey to great skin today.

This article is for general information and does not constitute medical advice. Prescription retinoids are prescription-only medicines and should be used only under the supervision of a qualified prescriber. Always read the patient information leaflet and report any suspected side effects to the MHRA via the Yellow Card scheme.