How Do I Know If a Cosmetic Treatment Actually Works?
Unfortunately, you cannot tell from the marketing and therein lies the problem.
Confident language, striking photographs and the phrase "clinically proven" can all sit comfortably on top of a treatment that has in reality barely been studied.
There is no reason a patient should have to read the research themselves. But there are a handful of questions that reliably separate a treatment with real support behind it from one that is simply being sold well. None of them require any medical knowledge.
Why are before-and-after photos almost useless?
Because almost every variable that affects how a face looks in a photograph is under the photographer's control.
Lighting is the largest one. Overhead light in the first image and soft frontal light in the second will produce a visible improvement on its own, with no treatment involved at all.
Then there is head position, camera angle, distance from the lens, expression, makeup, and the time of day. Skin looks measurably different at nine in the morning than at five in the afternoon.
Beyond that, you are only ever shown the results that worked. A gallery of thirty excellent outcomes tells you nothing about how many people were treated in total.
Photographs mean something when the conditions are standardised and stated. On their own, as evidence that a treatment works, they are close to worthless.
What does "clinically proven" actually mean?
On its own, very little. It is almost meaningless.
It is a marketing phrase rather than a medically accepted standard. It could describe a study of just twelve people with no comparison or placebo group.
What does good evidence look like?
It looks like this:
Researchers in Queensland took 903 adults and randomly assigned some of them to use broad-spectrum sunscreen every day, and the rest to use it whenever they felt like it. They followed both groups for four and a half years, then measured skin ageing objectively. The daily users showed around a quarter less photoageing [2].
Three features make that study worth something.
People were assigned randomly to each group.
There was a comparison group, so the result means something.
The follow-up was long enough for the effect to be real rather than temporary.
It is worth sitting with the conclusion, because it is not the one the aesthetics industry would choose. The best-supported anti-ageing intervention available is a sunscreen you can buy in a supermarket. Nothing on any clinic price list has evidence behind it of that quality.
What exposes a weak claim?
Three things, and you can ask about all of them in a consultation.
Was there a comparison or placebo group?
Much of what is published in aesthetic medicine is a case series: a practitioner treated fifteen patients, they mostly seemed pleased, and it was written up.
Without a comparison group there is no way to separate the treatment from everything else that happened, and in this field that "everything else" is substantial. Expectation, attention and better skincare habits after a consultation all push results in a flattering direction.How long were people followed?
Results reported at twelve weeks tell you nothing about where you will be at eighteen months, which is usually what you actually want to know.Who funded the work?
This does not disqualify a study, but it should change how sceptically you read it. One analysis of randomised trials in dermatology found conflicts of interest in around seven out of ten, rising to almost every trial funded exclusively by industry [3].
Manufacturers fund most research into their own products because very little public money goes into cosmetic medicine, so the alternative is often no research at all. The reasonable response is to ask whether independent work has found the same thing.
What if there is no evidence yet?
Then a practitioner should say so, and instead reason from their understanding of the underlying science.
Reasoning from science while being open about uncertainty is legitimate. Absence of published evidence is not proof that something fails. What is not legitimate is presenting a plausible theory as though it were a demonstrated result, and the difference is usually audible in how a practitioner talks about it.
Does "it works" also mean "is it safe"?
It should. But a treatment that works well in the right hands can cause permanent harm in the wrong ones.
The most serious complication of dermal filler is vascular occlusion, where product enters an artery and cuts off the blood supply to skin or, at worst, to the eye. A review pooling ninety-three published cases found that loss of vision was the dominant serious outcome, and most of those patients never fully recovered their sight [4]. The authors concluded that anyone injecting facial fillers needs a proper working knowledge of vascular anatomy.
Facial arteries vary considerably between individuals and do not always sit where diagrams suggest. Someone who has studied that anatomy injects differently, chooses their depth deliberately, keeps the drug that dissolves filler on the premises, and recognises within seconds what unusual pain and blanching mean. Someone who has learned injection points on a short course knows where the needle goes but not why, and the "why" is what you need when something goes wrong.
What should I ask before I book?
Four questions, and the manner of the answer matters as much as the content.
How does this treatment work, and what is the evidence for it in my case?
Clear, specific answers are a good sign. Deflection into brand names and testimonials is not.How long until I see a result, and how long will it last?
Vague answers here usually mean nobody has measured it.What are the risks, and what happens if one occurs?
For injectables, expect a specific answer about vascular occlusion and what is kept on site to treat it.What happens if I decide not to go ahead?
A practitioner confident in their reasoning has no difficulty saying that a treatment is not indicated. Anyone who cannot say no is not really assessing you.
The short answer
Treatments with real support behind them tend to be described in careful, slightly boring language, with timescales, limits and uncertainty. The ones with least behind them are described most enthusiastically.
That is not a coincidence. When there is evidence, it can be explained. When there is not, something has to fill the gap.
We examine this whole topic further in the evidence problem in aesthetic medicine - why you should always read the small print.
References
Advertising Standards Authority / Committee of Advertising Practice. Beauty and Cosmetics: Botulinum toxin products, CAP Code rule 12.12. Underpinned by the Human Medicines Regulations 2012. Available at asa.org.uk
Hughes MCB, Williams GM, Baker P, Green AC. Sunscreen and prevention of skin aging: a randomized trial. Annals of Internal Medicine. 2013;158(11):781-790
How prevalent are financial conflicts of interest in dermatology randomized controlled trials? A cross-sectional study. Clinical and Experimental Dermatology. 2021;46(4):715. https://pubmed.ncbi.nlm.nih.gov/33548070/
Vascular complications after facial filler injection: a literature review and meta-analysis. The Journal of Clinical and Aesthetic Dermatology. 2019. Sito G. et al. Vascular Complications after Facial Filler Injection: A Literature Review and Meta-analysis. J Clin Aesthet Dermatol. 2019 Jun;12(6) https://pubmed.ncbi.nlm.nih.gov/31360292/