What is dihydroxyacetone?
Dihydroxyacetone (DHA) is a ketotriose monosaccharide commonly used as the active ingredient in sunless tanning agents (fake tan). DHA is synonymous with glycerone or 1,3-dihydroxypropan-2-one.
What is dihydroxyacetone used for?
DHA was originally used as an artificial sweetener for diabetic patients. In the 1950s, it was also used orally for children with glycogen storage diseases, when it was discovered that it induced a brown pigmentation to the skin.
Currently, DHA is the only FDA-approved agent for sunless tanning. It has also been used in vitiligo to temporarily induce pigmentation in affected areas.
How does dihydroxyacetone work?
DHA is a three-carbon sugar that functions as part of the natural glycolysis pathway. It can be synthetically produced when Gluconobacter oxydans ferments glycerol, or through electrocatalytic oxidation.
DHA is thought to penetrate the stratum corneum when applied topically, where it undergoes a Maillard reaction (non-enzymatic glycation) with free amino acids such as glycine, alanine, leucine, and valine. The product of this reaction are melanoidins, which are large, pigmented nitrogenous structures resembling melanin, producing a darkening effect in the skin.
What are the precautions with dihydroxyacetone?
Although considered safe for most people, some should take caution when using DHA.
- Given that inhaled DHA may irritate pulmonary tissues, individuals with underlying pulmonary disease may need to be cautious with spray formulations of DHA.
- Individuals with a history of rosacea, allergic contact dermatitis, or atopic dermatitis may experience exacerbation of their skin condition with sunless self-tanner use, given additives to various formulations.
- As the effects of DHA in pregnant and paediatric patients have not been widely studied, it should be avoided in these populations.
Dihydroxyacetone formulations and application
Dihydroxyacetone is available in numerous forms, given its compatibility with water and oil-based solutions.
- Commonly available forms include creams and lotions, which often include moisturisers.
- Gel formulations are less common and are combined with delivery vehicles such as methylcellulose or hydroxyethylcellulose.
- Additionally, DHA has been incorporated into mousses and foams. These formulations offer relatively quick drying times and may be more suitable for oily skin.
- More recently, DHA has been used in water-based sprays, which may allow for less concentrated application to areas such as the face.
The DHA concentration in each formulation determines the resulting degree of tan. Concentrations range from 1–15%, most commonly 4–8%.
- Exfoliate prior to use, especially in areas where skin is thick.
- Dry skin adequately prior to use, to ensure even application.
- Apply methodically, using a circular motion and dividing the skin by region.
- Wash hands frequently to limit discoloration of the palms.
- Dilute the sunless tanner over joints to avoid discoloration in these areas.
- Allow the product to dry prior thoroughly after application.
- Continue to use adequate photoprotection.
In most cases, changes in pigmentation begin around one hour after topical application and are most prominent after 8–24 hours. Duration of pigmentation changes normally range from three to ten days. The required number and frequency of applications to maintain desired pigmentation changes varies based on bodily location. Areas with thinner skin require more frequent application of DHA compared to thicker skin.
More recently, microencapsulated formulations of DHA encourage slow release of active molecules, providing a longer-lasting tan as well as increasing product shelf-life.
What are the benefits of dihydroxyacetone?
- Tanned skin is often sought for aesthetic reasons. DHA results in the appearance of a tan while mitigating the known harmful effects of ultraviolet B (UVB)-induced tanning.
- Sunless tanner can be used throughout the year and in a variety of climates. DHA allows users to control when and where they tan.
- DHA may be applied by consumers without the need for professional assistance or advanced preparation of the skin.
- DHA has been added to some skincare products such as makeups and moisturisers, allowing consumers to incorporate it into their existing skincare routine.
- Compared to other forms of sunless tanners such as bronzers, which are easily washed off, the tan from DHA is more resistant to soap, water, and sweat.
What are the disadvantages of dihydroxyacetone?
- Potential variations in, or uneven, tan appearance depending on user skill and experience with the product, or defects in the DHA formulation or applicator device.
- If DHA is applied frequently and in high concentrations, it may lead to increased yellow and orange pigmentation, and a less ‘natural’ appearing tan.
- Some formulations of sunless tanners are associated with an unpleasant odour.
What are the side effects and risks of dihydroxyacetone?
It is unknown whether DHA penetrates deeper than the stratum corneum, which is more likely in the setting of a compromised epithelial barrier and may lead to adverse effects. DHA may also contribute to skin dryness, irritation, and contact dermatitis when applied excessively or in those with sensitivities to ingredients in sunless tanners.
The Maillard reaction induced by DHA can generate free radicals such as reactive oxygen species, resulting in damage to collagen, elastin, and DNA in cells. This may contribute to skin ageing and the appearance of wrinkles. Free radical generation is increased when DHA is used in combination with UV exposure. DHA may also limit the natural production of vitamin D after sunlight exposure.
The disadvantages and adverse effects associated with topical DHA use may be limited by using concentrations <10%, adding antioxidants to DHA formulations, and combining DHA with barrier-protecting agents and natural fragrances. Newer technologies including oxidant-free electrocatalytic oxidation may mitigate adverse effects of free radical damage.
DHA has also been demonstrated to cause respiratory tract and eye irritation if inhaled or contacting mucosal surfaces.
We suggest you refer to your national drug approval agency such as the Australian Therapeutic Goods Administration (TGA), US Food and Drug Administration (FDA), UK Medicines and Healthcare products regulatory agency (MHRA) / emc, and NZ Medsafe, or a national or state-approved formulary eg, the New Zealand Formulary (NZF) and New Zealand Formulary for Children (NZFC) and the British National Formulary (BNF) and British National Formulary for Children (BNFC).