The latest beauty fad to be doing the rounds in the celebrity circuit is the Hollywood EGF facial, or what Cate Blanchett and Sandra Bullock refer to as “the penis facial”.

First of all, it’s not what you’re probably thinking: no dicks are directly involved (or harmed) in the process. The treatment is so-nicknamed because it involves the application of an epidermal growth factor (EGF) serum developed from the progenitor cells of the human fibroblast taken from Korean new-born baby foreskin, which sounds bizarre enough in itself.

But you can breathe a sigh of relief – the cells that are actually added to the serum are, in fact, just clones of the original foreskin cells. Georgia Louise, beautician and penis facial originator, assured readers of as much in an interview with People magazine, saying: “I am always very mindful to explain radical serums and potions that I carry in my back bar so I always explain that EGF is derived from newborn baby foreskin, from which cells were taken and then cloned in a laboratory.”

But it still begs the question, why are people going around slapping on a serum made from the cells of baby foreskin?

It comes down to a substance called growth factors, which are extracted from stem cells – in this case, the stem cells derived from the foreskin. Why foreskins and why, specifically, Korean baby foreskins? Compared to other stem cells, foreskins are generally easier to obtain and utilize: When we are babies, our skin is at its best and the growth factors are at their most efficient (they decline in number and slow down as we age), and in South Korea, circumcision is near universal.

Back to growth factors. These are a group of amino acids or polypeptides first discovered in the eighties when it earned Rita Levi-Montalcini and Stanley Cohen a Nobel Prize in Physiology or Medicine. There are several types, including nerve growth factors, but epidermal growth factors (EGFs) are the ones most associated with the cosmetics industry and skin regeneration (though most companies use stem cells from plant-based sources).

EGFs are found naturally in the human body in several tissues, such as urine and saliva, and they are involved in various cellular processes, one of which is cell replication. EGFs stimulate the growth of cells including fibroblasts, which are responsible for the production of collagen.

Many in the cosmetics industry claim products containing EGFs help to replenish the aging body's diminishing supply. Applying EGF-filled serum or moisturizer topically, so they say, stimulates the body's own skin cells to multiply and regenerate, giving the applier a youthful complexion. Add in some more beauty industry lingo like renewal, skin elasticity, and radiance, and you get the idea. 

While stem cells are being used to treat skin wounds and burns, the science appears less certain when it comes to EGF-based cosmetics on aging but otherwise healthy skin. Many of the studies – including one in 2007, another in 2009, and this one in 2016 – that have shown positive results are at least partially funded and researched by people with ties to the skincare industry, so could skew a little biased. 

There has also been concern about EGF's link to cancer. While, ultimately, it didn't get very far because the association between the two is hard to prove, a lawsuit was made against a skincare brand selling EGF products because they failed to mention the cancer risks of applying said products to the skin.

Even dermatologists can't make up their mind when it comes to growth hormones.

Dr Amy Taub from Chicago, Illinois, told the Cosmetic Industry Forum: “I believe the growth factor story represents a significant step forward in our understanding of the biology of the skin and our attempts to modulate it to our advantage.” And, yes, she regularly recommends EGF serums to her patients.

Dr Matt Zirwas disagrees and said he feels "growth factors in skin care products are good for marketing, and totally worthless when it comes to actual results. Growth factors are proteins. Topically applied proteins cannot penetrate through intact stratum corneum to the living epidermis, hence cannot stimulate growth or the production of anything. Now, growth factors used in conjunction with microneedling, resurfacing, fractional resurfacing or injection are certainly effective.”

Which takes us back to the Hollywood EGF facial. As well as the application of EGF serum, the treatment involves a cleanse, an intensive TCA peel, micro-needling, and an electrifying mask – processes that, even without the serum, are bound to make your skin look younger, brighter, and more radiant at least temporarily. 

However, if it's less its effectiveness and more the ingredients in the serum that are concerning you, you might not want to know all the other strange things you can find in beauty products. Think snail secretion and placenta.