October 2020

The world of skincare is ever growing and there seems to be a new product every other week on the market claiming to make you look younger. Packaging a cream in a small round container and labelling it ‘eye cream’, seems to increase the price exponentially! But does it work?

I think it’s great that we have such a wide choice of products, however it’s not always easy to decipher which products work and which do not. In this blog post I look at the evidence base for the most common cosmeceutical products and ingredients, providing you with my opinion on their effectiveness.

What is a Cosmeceutical?

The FDA (Food and Drug Authority in the USA) does not recognise the term cosmeceutical and under the law the word has no meaning. However, the cosmetic industry uses this term to describe ingredients that have medicine like properties.

Like cosmetics they are available over the counter. Cosmeceuticals are not classed as medicines; this means that some companies producing such products can get away with minimal research and often products have not been through the rigorous testing and safety protocols that medicines go through.

Topical Vitamin C


  • Photo-protective
  • Reduced pigmentation

Vitamin C is not produced endogenously and so needs to be part of our diet. However, there has been significant interest in the anti-ageing and protective effect of vitamin C when topically applied to the skin.  

The active form of vitamin C is L-Ascorbic acid and can be bought in various strengths, often 10% or 15%. Vitamin C is an antioxidant and a tyrosinase inhibitor, (over activity of tyrosinase can result in increased pigmentation) it also plays a role in collagen synthesis (collagen is a protein that gives skin its supple and firm appearance). Vitamin C however is very unstable and becomes inactive when exposed to light. It also tends to have poor penetration into the skin. One way around this is by reducing the pH to below 3.5 and the addition of ferulic acid which helps with stability (1). L-Ascorbic acid should always come in an opaque bottle, as light will inactivate the product.  There are many products with vitamin C and manufacturers will use a variety of methods claiming it stabilises the product. However, there is no strong evidence as to which method works the best.

Interesting Fact

A deficiency in vitamin C can lead to conditions such as scurvy, fortunately in current times this is extremely rare. Ascorbus means “no scurvy”.

Does it work?

There are well structured randomised placebo controlled and double blind studies that have shown vitamin C improves pigmentation as a result of chronic sun exposure and also provides a photo protective element. (8) (9)


Photo-protective - yes
Reduced pigmentation - yes



  • Reduction of UV induced photoaging.
  • Reduced pigmentation
  • Anti-inflammatory

B3 or niacin is found in many foods such as eggs, red meat and legumes. A deficiency in vitamin B3 can lead to a condition known as pellagra. This is a rare condition but can be seen in cases of chronic alcoholism or chronic diarrhoea.

Niacinamide is a vitamin B3 derivative and can be bought over the counter as a topical application. The percentages in OTC products vary from 10% to 30%. Most studies have shown that a minimum 4% is required to have the desired effect.  However, one study has shown that percentages as low as 2% can lower oil production in the skin. (2) Niacinamide is a pre-cursor to nicotinamide adenine dinucleotide (NAD). This molecule has a function in repairing DNA damage that has been caused by the sun.

Interesting fact

A large trial (3) showed that taking oral vitamin B3 (500mg BD) reduced the risk of non-melanoma skin cancers.

NB topical niacinamide will not have this effect.

Does it Work?

There is a reasonable amount of research-based evidence that niacinamide has an impact of reducing pigmentation (although in one study the pigmentation recurred after stopping) (9) and has a degree of anti-inflammatory effect on the skin. One study also demonstrated its effects on reducing UV induced redness (10). It is well tolerated with minimal side effects.


Reduction of UV induced photo-ageing - yes
Reduced pigmentation - yes
Anti-inflammatory - yes

Hydroxy acids


  • Reduced pigmentation
  • Exfoliation
  • Reduction in acne

There are two main groups of hydroxy acids:

1. Alpha hydroxy acids: (AHA) These a plant derived acids and are used in multiple skin care products, including toners, creams and serums. They are water soluble.

Popular AHAs are (among others)

  • citric acid (from citrus fruits)
  • glycolic acid (from sugar cane)
  • lactic acid (from lactose or other carbohydrates)

Glycolic acid is the best studied AHA, it is touted as being a good exfoliator and a good humectant thereby hydrating the skin.

2. Beta hydroxy acids: (BHA) These are lipid soluble acids which means they are better at penetrating the skin.  The most common BHA is salicylic acid. BHAs are also thought to have anti-inflammatory properties and an impact on oily, acne prone skin.

Interesting fact

BHAs are derived from plants, mostly the leaves and bark of the willow trees. It is a derivative of aspirin (acetylsalicylic acid). It has been used for centuries and archaeologists have found traces of salicylic acid on 7th century pottery fragments in Colorado. (13)

Do they work?

There have been many studies on both glycolic acid (AHA) and salicylic acid (BHA).

A randomized, double‐blind study evaluated 4% glycolic acid, and 8% glycolic / 2% citric acid (11). The 4% glycolic acid group showed improved fine lines at 8 weeks. The 8% glycolic / 2% citric acid group reported improved hyperpigmentation and roughness.

Salicylic acid is often found in the 2% strength in various over the counter products. At this concentration it is unlikely to have much of an impact on acne.

Salicylic acid is often better tolerated than glycolic acid which can often produce a burning or stinging sensation and is also reported to increase photosensitivity (12).


Reduced pigmentation - yes
Exfoliation - yes
Reduction in acne - possibly



  • Anti-ageing- reducing fine lines and wrinkles
  • Reduced pigmentation
  • Improved skin elasticity
  • Improved skin texture and tone
  • Reduces acne

Retinol is a vitamin A derived topical application. There are a few different types that are available. I will be discussing the effects of the OTC products. The prescription products have known and proven benefits. However, the data on OTC products may not be as robust.

Vitamin A derivatives

Natural vs Synthetic


OTC vs Prescription

Retinol esters

Retinyl palmitate

Retinyl acetate

Retinyl linoleate

Retinyl Propionate








Retinaldehyde (Retinal)




Tretinoin (Retin A, Retinoic acid)












Vitamin A derivatives go through a variety of conversions before they become active in the skin. The stages are as follows.

Retinyl esters → Retinol → Retinal →Retinoic acid

The conversion occurs at a cellular level in the skin therefore, with each conversion you will be getting less retinoic acid (which is the active product).

Do OTC retinols work?

Studies have shown Retinol esters tend not to work for the effects they claim to help with.

There are some studies showing that retinols however do have an impact. A small study looked at comparing OTC retinol vs prescription strength retinoic acid. (4) After 12 weeks of application of OTC retinol (0.1%) a reduction in facial wrinkles was seen, this was of a lesser degree to what one would see with application of retinoic acid.

Another study in 2015 (5) showed retinol had improved crow's feet fine lines by 44%, and mottled pigmentation by 84%.

Interesting fact

Retin A was co-invented by Professor Kligman in 1969. It is claimed that he carried out many of his experiments for various other products on numerous inmates at a prison in Philadelphia. Kligman also coined the term ‘cosmeceutical’ in 1970.

Do they Work?

OTC retinols definitely do work, but they will have less of an impact than prescription retinoids and it will take you longer to achieve the desired results. However, the upside is that they cause less irritation than a prescribed retinoid. The main downside is the expense; some OTC retinols cost over £170. There probably isn’t much of a difference between a cheap and expensive retinol, except for the packaging and possibly texture of the application.


Anti-ageing- reducing fine lines and wrinkles - yes
Reduced pigmentation - yes
Improved skin elasticity - yes
Improved skin texture and tone - yes
Reduces acne - yes

Hyaluronic acid


  • Moisturiser
  • Anti-ageing
  • Reduces Wrinkles

Hyaluronic acid (HA) is found in many cosmetic products. HA is a natural substance that is found in the dermis of the skin and it is secreted by cells known as fibroblasts. Over time the production of HA is reduced, this is owing to factors that damage the skin including smoking, sun exposure and of course age will also play its role. HA is a very powerful humectant and 1g of HA can absorb or bind up to 1000g of water, meaning it’s an excellent moisturiser. HA can be found as creams, serums and in many injectable fillers. HA cream and serums however tend to remain in the epidermis (the outer layer of skin) and do not penetrate into the dermis (deeper layer).

The moisturising effect of HA can also be dependent on the climactic conditions you live in. So, if you are living in a region of high humidity, the HA can draw water in from the environment and use it to moisturise the skin. However, in drier climates it will take water from the skin and this will give you a temporary plumping effect but may dry the skin.

Interesting fact

in 1934, two scientists isolated HA from bovine vitreous humour- the eyeball! The first pharmaceutical-grade HA was produced in 1979 by Balazs, and is currently used in intraocular lenses, wound healing, treatment of joint and of course skin conditions.

Does it work?

As a moisturiser HA works very well. However, as an anti-ageing product, due to the fact that it does not absorb into the deeper layer of the skin, it will not have a long-term benefit.


Moisturiser - yes
Anti-ageing - no
Reduces wrinkles - temporarily

Vitamin E


  • Improves under eye dark circles
  • Anti-inflammatory
  • Scar reduction
  • Wound healing
  • Burn healing

Vitamin E is an important fat-soluble vitamin synthesised by plants. The biologically active form is α‐tocopherol.  It is an important ingredient in many cosmetic products and most of the over-the-counter anti-ageing creams contain 0.5%–1% of vitamin E.

Does it Work?

A number of studies that have looked into the claim of scar reduction, wound healing and burn healing have been disappointing and show no clear evidence of benefit (6). A study in 2004 looked at the effect of a gel containing phytonadione, (Vitamin K1), retinol and vitamin C & E on under eye dark circles and found that there was no clear evidence of a reduction of pigmentation in the 57 patients. They saw a slight reduction in wrinkles (likely secondary to the effects of the Retinol or vitamin C) (7). More studies are required to evaluate the effect of topical Vitamin E.

Interesting fact

Vitamin E has been known to cause contact allergy on the skin after application. Although this is rare in some cases it has resulted in eczema, urticarial (hives) and erythema multiforme (a severe drug like rash).


Improves under eye dark circles - no
Anti-inflammatory - no
Scar reduction - inconclusive
Wound healing - inconclusive
Burn healing - inconclusive



  • Provide collagen for the skin
  • Increase body’s collagen production
  • Anti-ageing

Collagen – responsible for strength and elasticity – is a protein synthesised by fibroblasts in the skin. Its main function is to provide support to the structures of the skin, however, with age collagen production naturally reduces. There are now a variety of products on the market that contain collagen, claiming they help to boost the skin’s own collagen production and ‘plump’ up the skin.

Interesting fact

More recently oral collagen supplements have become extremely popular as a mechanism to improve skin elasticity and slow down the ageing process. However, to date there is no convincing data to show that oral collagen has any benefit at all.

Does it Work?

Collagen is a large and complex molecule. The size of the molecule means that it does not penetrate the epidermis, let alone the dermis where most of the collagen is formed. There are no large clinical studies that evaluate the effect of topical collagen. At best it acts as a nice moisturiser.


Provide collagen for the skin - no
Increase body’s collagen production - no
Anti-ageing - no

Final thoughts

If you feel one of the above products works well for you even though there is minimal evidence, then I would suggest that you continue using it. All the products above are relatively safe to use and although you may not see much benefit, it is extremely unlikely they will cause any harm.

Dr Adil Sheraz
Consultant Dermatologist

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  2. Draelos ZD, Matsubara A, Smiles K. The effect of 2% niacinamide on facial sebum production. J Cosmet Laser Ther. 2006 Jun;8(2):96-101. doi: 10.1080/14764170600717704. PMID: 16766489.

  3. Chen, Andrew C, et al. A phase 3 randomized trial of nicotinamide for skin-cancer chemoprevention. The New England Journal of Medicine. [Online] 22 October 2015. [Cited: 19 May 2019.] 

  4. Kong R, Cui Y, Fisher GJ, Wang X, Chen Y, Schneider LM, Majmudar G. A comparative study of the effects of retinol and retinoic acid on histological, molecular, and clinical properties of human skin. J Cosmet Dermatol. 2016 Mar;15(1):49-57. doi: 10.1111/jocd.12193. Epub 2015 Nov 18. PMID: 26578346.

  5. Randhawa M, Rossetti D, Leyden JJ, Fantasia J, Zeichner J, Cula GO, Southall M, Tucker-Samaras S. One-year topical stabilized retinol treatment improves photodamaged skin in a double-blind, vehicle-controlled trial. J Drugs Dermatol. 2015 Mar;14(3):271-80. PMID: 25738849.

  6. Topical vitamins, minerals and botanical ingredients as modulators of environmental and chronological skin damage.Chiu A, Kimball ABBr J Dermatol. 2003 Oct; 149(4):681-91.

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  11. Mekas MChwalek JMacGregor Jet alAn Evaluation of Efficacy and Tolerability of Novel Enzyme Exfoliation Versus Glycolic Acid in Photodamage TreatmentJ Drugs Dermatol20151413061319.

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  13. "1,300-Year-Old Pottery Found in Colorado Contains Ancient 'Natural Aspirin'"Archived from the original on 2014-08-13. Retrieved 2014-08-13.