DMAE (dimethylaminoethanol) is a skin care ingredient enthusiastically touted by many skin care vendors. One of the reasons for its popularity is that it is one of the very few agents (perhaps even the only one) shown to produce some skin tightening and modestly reduce facial sag.
However, a 2007 study published in the British Journal of Dermatology raised safety concerns regarding topical DMAE. Dr. Morissette and colleagues, from the University of Quebec, studied the effect of DMAE in human skin cell cultures and rabbit skin.
The researchers found that adding DMAE to the cultures of fibroblasts (key type of skin cells) produced the effect known as vacuolization. Vacuolization is often observed in cells after various types of damage as cells try to encapsulate and excrete foreign agents and/or their own damaged components. Hence the researches concluded that the vacuolization induced by DMAE was suggestive of cell damage. They also observed that DMAE impaired the ability of fibroblasts to divide. Notably, the above adverse effects reversed after DMAE had been washed out of the culture following a short-term exposure. (Long-term exposure has not been studied.)
The application of 3% DMAE to the skin of rabbit ear resulted in the thickening of epidermis and the so-called perinuclear swelling (swelling of the area around the nucleus) in epidermal cells. This effect was an indirect indication (albeit not a proof) of vacuolization and cell damage.
What do these results mean for the common use of DMAE in skin care? Unfortunately, this is not an easy question to answer. Here are just some reasons why:
Almost any substance, including those known to be beneficial, can be toxic under certain condition, e.g. at high concentrations, at certain levels of pH or temperature, in combination with other chemicals, and so forth. For instance, adding too much vitamin C to a fibroblast culture is lethal to the cells. Yet, small, pH-balanced amounts of vitamin C are not only protective but also stimulate collagen synthesis. Therefore, it is hard to say whether one can compare the treatment of fibroblast culture in the above DMAE study to the typical DMAE use in skin care.
The test on rabbit ear skin was insufficiently comprehensive and possibly invalid. First, this test involved the alkaline form of DMAE whereas DMAE generally used in skin care formulas is pH-balanced to be approximately neutral. The damage may not have occurred had the researchers used pH balanced DMAE. Second, the rabbit ear test involved only epidermal cells. Ideally, fibroblasts should have been examined as well -- they have a greater role in the skin's ability to maintain youthfulness. Furthermore, epidermal vacuolization was not directly observed but only suggested as a probable explanation for perinuclear swelling. Also, rabbit ear skin is known to be considerably more sensitive than human facial skin.
The researches stated that the effects of DMAE in their cell culture where similar to triethnolamine. However, triethnolamine has been used in skin care for decades and while it might cause some low-level skin damage in some people (even that is debatable), it is not seriously toxic to the skin at low concentrations. This adds to the problem of using the study's results when evaluating potential risks of DMAE in common skin care.
Even if commonly used DMAE formulas produce some degree of skin damage, this does not automatically disqualify DMAE as a skin care ingredient. In fact, many skin rejuvenation treatments, such as alpha-hydroxy acids, chemical peels, laser resurfacing and others, work by producing controlled skin damage. The resulting healing process improves the structure of the skin matrix and leads to a younger looking skin. Therefore, the question is not just whether DMAE may produce skin damage, but whether such damage, if any, may be transient and perhaps even beneficial in the longer-term.
Dr. Morissette's study is noteworthy but is difficult to extrapolate to typical cosmetic use of DMAE. Ideally, one should conduct a human clinical trial where the subjects are treated for at least several weeks with topical DMAE formulas with the range of concentrations and pH levels typical in skin care products. (The control group would be treated with inactive vehicle only.) After that, all the skin layers should be carefully measured and analyzed.
What to do until such data is available? To be on the safe side, you could just wait and refrain from using topical DMAE. If you do not want to wait, it may be prudent not to exceed the strength of 1% of DMAE and watch out for any adverse effects, such as skin irritation.