Retinoids consist of natural and synthetic derivatives of vitamin A that can be found in both prescription medications and over the counter cosmeceuticals.
Retinoic acid increases cell turnover and stimulates collagen and elastin production.
Therefore, it can treat pigmentation, cystic acne and wrinkles.
RA is thought to reduce mottled hyperpigmentation by enhancing epidermal cell turnover.
It reduces fine lines and wrinkles by increasing the capacity of the epidermis to hold water through stimulation of glycosaminoglycan (GAG) synthesis, and by stimulating collagen synthesis through increases in transforming growth factor (TGF-beta) and procollagen.
RA reduces skin roughness by modulating the expression of genes involved in cellular differentiation and proliferation, hence promoting epidermal cell turnover.
Surface roughness, mottled hyperpigmentation, and fine wrinkles demonstrate the most significant improvement with RA therapy.
Forms of retinoids:
The topical cosmeceutical retinoids include many different forms of vitamin A: Retinyl esters, Retinol, Retinaldehyde, and the group of Oxoretinoids.
Retinoic acid (RA) is the biologically active form of vitamin A.
It has been extensively studied and used as an effective topical treatment for photoaging, acne, and numerous other dermatological disorders.
Retinoic acid can, however, be irritating to the skin, limiting its use in some patients.
Retinol (ROL) and retinaldehyde (RAL) are gentler yet still effective topical alternatives to Retinoic acid (RA).
In the skin, ROL is oxidized into RAL, which in turn needs to be oxidized into RA before it will be biologically active.
The other cosmeceutical retinoids, retinyl palmitate and retinyl-acetate, are retinoid esters and are NOT considered effective against photoaging.
While ROL and RAL containing cosmeceuticals have not been shown to produce the magnitude of clinical results obtained with the prescription products that are approved and used to treat photoaging (such as tretinoin, tazarotene), many consumers are pleased with their cosmetic results.
Cosmeceutical retinols – which need to be converted into retinoic acid before the skin can use it – use around 10 times more retinol content than prescription retinol.
When to start:
It is best to start using retinoids at age mid-20s, when the first signs of ageing are about to occur.
Any Retinoid products can cause dryness, redness and flaking of the skin. These side effects usually last for the first 2 weeks of use and then resolve.
Side effects can be minimised by using the product just once or twice a week, gradually increasing frequency as tolerated.
A common way to use retinoids is for 3 months, then with a 3 month break. This is due to research suggesting that this is just as effective as continuous use; cell turnover is no longer increased after 3 months of use.
Once skin cells have adapted to the strength of the retinoid being applied, any irritation generally stops. Skin is unlikely to flare up again unless the retinoid is switched to a stronger version.
When to apply:
Retinoid products are thought to cause sensitivity to UV rays, although there is conflicting evidence on this.
They are known to break down in sunlight, which is why they will not come in a clear bottle, and why they should be applied at night rather than in the morning.
A good sunblock is essential regardless of retinol use, to reduce the risk of skin cancer and photoageing.
Who should not use retinoids:
Rosacea, eczema or psoriasis can be worsened by retinoids, as they can make the skin more vascular.
It can be unsuitable for sensitive skin, and can cause worsening inflammation if the skin is prone to this.
It can be unsuitable for those with dry skin, as retinoids are drying.
What strength to use:
This depends on the product – and where on the pathway it is in the process of being converted to the active molecule retinoic acid.
The below list reads from weakest to strongest product:
Retinyl palmitate has to be converted 3 times within the skin to become active – to retinol, then retinaldehyde, then retinoic acid.
It is the lightest and most gentle form of vitamin A.
It is typically used for people who cannot tolerate retinol due to sensitive skin.
Retinol is the next step up – and is the over-the-counter standard.
There are a lot of over the counter products with a low percentage of retinol – from 0.01 to 0.03%.
Moderate strength products contain 0.1% to 0.3%
Higher strength would be 0.5% to 2% retinol.
Retinaldehyde is the next step after retinol – one step closer to the active molecule. It is the closest form to the active molecule available without a prescription.
A typical strength of retinaldehyde is 0.1%.
Tretinoin – is prescription only. It is also known as all-trans-retinoic-acid – are typically the mildest form of prescription retinoids. This is the active molecule.
The weakest tretinoin cream is 0.005%
Moderate strength would be 0.025 – 0.05%
The strongest available is usually 0.1%.
Synthetic retinoids: Developed to treat acne, but also having anti-ageing effects:
Isotretinoin (13-cis-retinoic acid). Trade name “Accutane” or “Roaccutane”.
Adapalene – “Differin” – this is a newer generation of synthetic retinoid that was developed to treat acne. It is more chemically stable than other retinoids.
Tazarotene – another new retinoid developed for acne, this binds to fewer receptors than other forms, making it less irritating to the skin.
Encapsulation is a wall surrounding an ingredient.
This can be composed of polymers, phospholipids, cyclodextrin, some surfactant type materials, waxes or combinations.
Encapsulation is used to delay the release, increase absorption, prevent penetration (keep it on top of the skin), stabilise or protect the ingredient from interacting with other molecules in the formula.
If encapsulated, the retinoid is housed in a carrier system, to protect its integrity and improve its ability to penetrate the skin effectively. Apolymer encapsulated retinol enhances stability and decreases irritation.
The encapsulated retinol is immobilised to drip feed Vitamin A into the skin over hours. This timed delivery to the skin results in less irritation.
What can be combined with Retinoids:
Niacinamide:Some formulations combine a retinoid with niacinamide (a form of vitamin B3). Niacinamide boosts ceramide production – making skin more robust and tolerant of irritants – and has anti-inflammatory properties. This means that the retinol may not cause as much irritation if combined with this. The retinol induced initial peeling (a sign that it is working) will not be affected however.
Vitamin E (Tocopherol):as this is moisturising, anti-inflammatory, and anti-oxidant, it can help to soothe the skin when combined with a retinoid.
Hyaluronic acid:This is a hydrating agent and so can negate the drying effect of retinoids.
Ceramides:These are lipids (fats) that are found naturally in the skin.
They soothe the skin and boost the efficacy of other skincare ingredients.
Ceramides can be found in certain retinoid skincare products.
Peptides:These are short chains of amino acids – i.e. fragments of proteins. They can have anti-oxidant and anti-inflammatory properties.
Azelaic acid:this is a naturally occurring acid found in grains such as barley, wheat and rye. It has anti-microbial and anti-inflammatory properties.
It can reduce skin blemishes and pigmentation.
Phenols (eg resveratrol):These have antioxidant and anti-inflammatory properties.
Omega-3 fatty acids:These are good moisturisers which can help with the drying effects f retinoids
Colloidal oatmeal:This is soothing and moisturising, so works well with skin care products such as retinoids that can irritate the skin.
What can sometimes be used with retinoids:
AHAs and BHAs:Retinol combined with either an Alpha hydroxy acid or beta hydroxy acid can improve the results obtained from both ingredients, and further fade hyperpigmentation in the skin.
Using both or all three together can however increase irritation to the skin.
Therefore, a typical anti-ageing skincare routine might be a daily retinoid, with an acid weekly or monthly to exfoliate.
Lactic acid or Glycolic acid: These are both members of the Alpha hydroxy acid (AHA) family.
They are moisturising forms of AHA.
Glycolic is derived from sugar cane and lactic acid from milk, but they both work in the same way.
They exfoliate the skin gently but moisturise as well.
Vitamin C: as this is unstable, layering it with other products can render it useless. Vitamin C can be used in the morning and retinol at night, but they shouldn’t be used at the same time.
If the retinoid formula is acidic, then the vitamin C will not be destabilised. Retinoids are not harmed by an acidic environment so a combination product is possible, but ONLY at the correct pH.
What should NOT be used with retinoids:
Benzoyl peroxide(BPO) for acne:
Using both creams together can deactivate the retinoid.
BPO is a very drying product, and can cause redness and irritation.
BPO and retinoid products can be used separately if needed, for example BPO in the morning and retinol at night, but this may not be tolerated due to these increased side effects.
How long until results are seen:
It takes an average of 12 weeks for retinoic acid to produce noticeable changes in the skin.
The stronger the formulation, and the more frequently it is used, the quicker results will be seen.
- Retinoids are an evidence based anti-aging ingredient.
- Retinoic acid increases cell turnover and stimulates collagen and elastin production. Therefore, it can treat pigmentation, cystic acne and wrinkles.
- Irritation, dryness, redness and peeling can occur, particularly in the first 2-3 weeks.
- It takes around 12 weeks for noticeable skin benefits to be seen
- Retinol is converted to retinaldehyde, which is then converted to retinoic acid – the active molecule. A product is stronger if it is further along this chain.
- Each of these is available in different strengths.
- It is sensible to start with a low potency product, building up gradually.
- Retinoid products should be applied at night
- Formulations can contain retinoids and other skin care ingredients, particularly soothing or moisturising ones.