Tretinoin & Retinoids

Important information about tretinoin in the UK

Tretinoin is a prescription-only medicine in the UK. The formulations referenced on this page require individual medical assessment and prescription when clinically appropriate. This page provides factual information about tretinoin, its clinical uses, available concentrations, formulation types and principal safety considerations. It is not a guide to selecting a product, brand or strength.

What is tretinoin?

Tretinoin, also known as all-trans retinoic acid or retinoic acid, is a topical retinoid derived from vitamin A. It is used in dermatology for acne and may also be considered under medical supervision in certain photoageing and pigmentation treatment plans.

Unlike cosmetic retinol and retinal, tretinoin does not require conversion within the skin before becoming retinoic acid. It interacts directly with retinoic acid receptors in skin cells. This difference affects its biological activity, tolerability and prescription status.

Topical tretinoin should not be confused with oral tretinoin, which is a separate medicine used in specialist haematology settings.

How does topical tretinoin work?

Tretinoin binds to nuclear retinoic acid receptors within skin cells. This affects gene expression involved in cell differentiation, keratinisation, inflammation and extracellular matrix regulation.

Its principal effects include:

• Normalising the way cells develop and separate within the follicle

• Reducing the formation of microcomedones that can develop into blocked pores

• Influencing epidermal cell turnover and the distribution of pigment

• Supporting changes in dermal collagen associated with long-term treatment

• Improving aspects of skin structure affected by cumulative ultraviolet exposure

Tretinoin is sometimes described simply as an exfoliant, but this is incomplete. It does not work in the same way as an alpha-hydroxy or beta-hydroxy acid. Its effects arise primarily from retinoid-receptor activity and changes in cellular behaviour.

Clinical uses of tretinoin

Acne

Topical tretinoin is an established treatment for acne. It helps prevent the development of comedones by normalising follicular keratinisation and reducing obstruction within the pilosebaceous unit.

It may be considered for comedonal acne and for treatment plans involving inflammatory lesions. Acne management sometimes combines a topical retinoid with another medicine, but the suitability and compatibility of any combination must be assessed individually.

Visible response develops over time. An initial increase in dryness, irritation or inflammatory lesions does not necessarily establish treatment failure, but significant or persistent worsening requires clinical review.

Photoageing and sun-damaged skin

Tretinoin has been extensively studied in relation to photoaged skin. Under medical supervision, it may be considered for features including fine lines, rough surface texture, mottled pigmentation and other changes associated with cumulative ultraviolet exposure.

Clinical changes develop gradually and depend on concentration, formulation, treatment consistency, tolerance and photoprotection. Tretinoin does not reverse every structural effect of ageing or ultraviolet damage.

New, changing or irregularly pigmented lesions require appropriate assessment and should not be treated as ordinary sun spots without a diagnosis.

Hyperpigmentation

Tretinoin may be used within clinician-directed treatment plans for certain forms of hyperpigmentation, including post-inflammatory hyperpigmentation and melasma.

It can affect epidermal turnover, pigment distribution and the penetration of other topical ingredients. However, excessive irritation may aggravate post-inflammatory pigmentation, particularly in skin that is prone to pigmentary change.

Tretinoin may sometimes be prescribed alongside hydroquinone or other pigmentation treatments. Combining active ingredients can increase irritation and should only follow the individual treatment plan.

Skin texture

Changes in epidermal organisation and longer-term effects on dermal structure may improve the appearance of rough or uneven skin texture. Response varies and should not be assumed solely from the stated tretinoin concentration.

Tretinoin and the retinoid family

“Retinoid” is a broad term covering natural and synthetic substances related to vitamin A. Tretinoin, retinol, retinal, adapalene and tazarotene are all retinoids, but they are not interchangeable.

Tretinoin

Tretinoin is retinoic acid in its active form. Topical tretinoin is prescription-only in the UK.

Retinol

Retinol is used in non-prescription cosmetic skincare. It must undergo conversion within the skin before retinoic acid is produced. Its activity depends partly on the formulation and the efficiency of these conversion steps.

Retinal

Retinal, also called retinaldehyde, is another cosmetic retinoid. It requires one principal conversion step to become retinoic acid.

Adapalene

Adapalene is a synthetic topical retinoid used principally in acne treatment. It has a different receptor-binding and stability profile from tretinoin.

Tazarotene

Tazarotene is a synthetic prescription retinoid used for particular dermatological indications in some countries. It is not the same medicine as tretinoin and has a distinct potency, tolerability and prescribing profile.

Tretinoin concentrations

The formulations referenced on this page contain tretinoin at 0.025%, 0.05% or 0.1%.

The percentage represents the concentration of tretinoin in the complete formulation:

• 0.025% contains 0.25 mg of tretinoin per gram

• 0.05% contains 0.5 mg of tretinoin per gram

• 0.1% contains 1 mg of tretinoin per gram

A higher percentage means a greater concentration of tretinoin, but it does not automatically mean that the formulation will be more appropriate or produce a better overall outcome.

Concentration must be considered alongside:

• Cream or gel vehicle

• Complete formulation and inactive ingredients

• Skin condition and treatment indication

• Previous retinoid exposure

• Skin-barrier condition and sensitivity

• Application frequency

• Other topical or systemic treatments

• Degree of irritation that can be tolerated safely

Different products containing the same tretinoin concentration should not automatically be treated as interchangeable.

Further information is available in How tretinoin 0.025%, 0.05% and 0.1% concentrations differ.

Tretinoin cream and gel formulations

Tretinoin is available in different topical vehicles. The vehicle can affect texture, application, drug delivery, stability and tolerability.

Cream formulations

Cream formulations contain a mixture of water, emollients, emulsifiers and other supporting ingredients. Individual cream bases differ, so two tretinoin creams at the same concentration may not feel or behave identically.

Gel formulations

Gel formulations generally have a lighter vehicle and may differ from creams in their solvent content, absorption and irritation profile. A gel should not automatically be assumed to be stronger, weaker or more suitable for a particular skin type solely because it is a gel.

The complete formulation and individual clinical circumstances matter alongside the tretinoin percentage.

The tretinoin adjustment period

Dryness, redness, scaling, tightness, stinging and increased sensitivity can occur when topical tretinoin is introduced. These effects are commonly described as retinoid irritation or retinoid dermatitis.

Some people also experience a temporary increase in visible acne lesions. The informal term “tretinoin purge” is frequently used for this response, although not every breakout after starting tretinoin is caused by accelerated comedonal turnover.

Persistent inflammation can compromise the skin barrier and may worsen post-inflammatory pigmentation. Significant burning, swelling, blistering, crusting or prolonged irritation requires medical advice.

Further information is available in Tretinoin adjustment and temporary acne changes.

Principal safety considerations

Important considerations associated with topical tretinoin include:

• Dryness, redness, peeling, stinging and skin irritation

• Increased sensitivity when combined with exfoliating or irritating products

• Avoiding contact with the eyes, lips, nostrils and mucous membranes

• Avoiding application to broken, acutely inflamed or severely irritated skin unless specifically directed

• Following the prescribed application area, frequency and duration

• Using appropriate broad-spectrum sun protection

• Reporting severe or persistent reactions to the prescribing clinician

• Following the storage instructions supplied with the particular formulation

Suitability may require additional consideration where eczema, rosacea, perioral dermatitis or another active inflammatory skin condition is present.

Tretinoin and pregnancy

Topical retinoids, including tretinoin, are contraindicated during pregnancy as a precaution. They should also not be used when planning a pregnancy.

Anyone who becomes pregnant while using topical tretinoin should stop treatment and contact the prescribing clinician. Breastfeeding suitability requires individual medical advice, including consideration of the intended application area and the possibility of direct infant contact.

Tretinoin and sun exposure

Ultraviolet exposure contributes to inflammation, pigmentation and photoageing. Irritated skin may also be less tolerant of environmental exposure.

Broad-spectrum sun protection is therefore an important part of most tretinoin treatment plans. This remains relevant throughout the year and is not limited to hot or sunny weather.

Tretinoin itself can also be sensitive to light, although photostability differs between formulations. Product-specific storage and application instructions should be followed.

Further information is available in Tretinoin, retinoids and seasonal sun exposure.

Tretinoin with other active ingredients

Compatibility depends on the formulation, treatment indication and individual tolerance.

Benzoyl peroxide can affect the stability of some conventional tretinoin formulations, although compatibility differs between products and formulation technologies. Acids, exfoliants and other retinoids may increase irritation. Hydroquinone and tretinoin may be prescribed within the same pigmentation protocol in selected cases.

Products should not be combined or separated according to a general rule without considering the prescribed treatment plan.

Further information is available in Tretinoin and hydroquinone: should they be used together?.

Frequently asked questions

Is tretinoin the same as retinol?

No. Both belong to the retinoid family, but tretinoin is retinoic acid in its active form. Retinol must be converted within the skin before retinoic acid is produced. Tretinoin is prescription-only in the UK, whereas retinol is used in cosmetic products.

Is Retin-A the same as tretinoin?

Retin-A is a brand name associated with topical formulations containing tretinoin. Tretinoin is the active ingredient. Other branded and generic formulations can contain the same active ingredient but may differ in concentration and vehicle.

Is Ketrel the same as tretinoin?

Ketrel is a brand of topical cream containing tretinoin 0.05%. Its active ingredient is tretinoin, but its complete cream formulation is specific to that product.

Is tretinoin available in the UK?

Tretinoin is a prescription-only medicine in the UK. The individual formulations referenced on this page require medical assessment and prescription when considered clinically appropriate.

Further information is available in Tretinoin prescription status and access in the UK.

What strengths of tretinoin are available?

The topical formulations referenced here contain tretinoin at 0.025%, 0.05% or 0.1%. Other concentrations and combination formulations exist internationally. The appropriate concentration cannot be established from percentage alone.

Is 0.1% tretinoin better than 0.025%?

Not automatically. A higher concentration can increase biological exposure but may also increase irritation. Overall response depends on the formulation, indication, consistency, tolerance and clinical plan.

What is the difference between tretinoin cream and gel?

Both can contain the same active ingredient, but their formulation vehicles differ. This can affect texture, delivery, stability and tolerability. Neither vehicle is universally preferable.

Does tretinoin thin the skin?

Tretinoin can initially cause dryness, scaling and changes in the outermost skin layer, which may create a sensation of fragility. This should not be confused with permanent thinning of the skin. Longer-term tretinoin treatment has been associated with changes in epidermal organisation and dermal collagen.

How quickly does tretinoin work?

Response depends on the treatment indication, concentration, formulation, application pattern, tolerance and consistency. Acne response is generally assessed over weeks, while structural changes associated with photoageing may require a longer treatment period. A guaranteed timetable cannot be applied to every person.

Who may not be suitable for tretinoin?

Pregnancy and planned pregnancy are important contraindications. Active inflammatory skin conditions, impaired skin barrier, previous severe retinoid reactions and interacting treatments may also affect suitability. Individual assessment is required.

Further information is available in When tretinoin may not be suitable.

Related clinical information

• How tretinoin 0.025%, 0.05% and 0.1% concentrations differ

• Starting tretinoin: clinical and practical considerations

• Tretinoin adjustment and temporary acne changes

• Tretinoin prescription status and access in the UK

• Tretinoin and hydroquinone: should they be used together?

Last updated: September 2026.