412 JOURNAL OF COSMETIC SCIENCE
These are the four sensitive skin subtypes:
• Acne type (papules, pustules).
• Rosacea type (erythema).
• Stinging or burning.
• Allergic.
Pigmented Versus Nonpigmented. In the BSTS, the term “pigmented skin” is a skin type that
needs skin lightening ingredients in its skin care routine due to uneven skin pigmentation. It
does not refer to an individual’s base skin color or Fitzpatrick skin type. Instead, it specifically
denotes the presence of unwanted hyperpigmentation. It is important to note that the
designation of a nonpigmented skin type does not necessarily mean the person does not have
melasma, dark spots, or freckles. A nonpigmented type means the subject does not want to
lighten spots on the skin. This approach underscores the importance of considering patient
preferences in assigning a BST, as opposed to relying solely on camera imaging, which may not
adequately capture the nuances of an individual’s skin concerns and desired skin outcomes. The
pigmented designation does not imply that the patient has a higher risk of postinflammatory
hyperpigmentation. It just signifies that unwanted dyschromia is currently present on the face,
the subject wants to lighten it, and skin lighteners should be in the skin care routine. When
the hyperpigmentation clears, the subject changes to a nonpigmented skin type.
Wrinkle-Prone Versus Tight. Aging skin for the BSTS is defined as age over 30 or habits such
as sun exposure that increase the risk of skin aging. Wrinkle-prone skin types are assigned
ingredients in their routine to lower the risk of skin aging or to treat wrinkles, depending
on the person’s questionnaire responses to the questions about lifestyle habits. In an analysis
of more than 100,000 skin type quizzes, over 50% of individuals between the ages of 20
and 29 had lifestyle habits that warranted increasing antioxidants, DNA repair enzymes,
retinoids, and other protective and repair ingredients into the skin care routine. The tight
skin types are under the age of 30 with minimal sun exposure and healthy habits. The
tight designation indicates younger or well-maintained skin.
The 16-skin types listed in Table I are derived by combining these 4 dichotomous
parameters. The benefit of using the BSTS to build a custom skin care routine is that it
Table I
List of 16 BSTs
Skin Type 1- DSPT – Dry, sensitive, hyperpigmentation, tight
Skin Type 2- DSNT – Dry, sensitive, no hyperpigmentation, tight
Skin Type 3- DSPW – Dry, sensitive, hyperpigmentation, wrinkle-prone
Skin Type 4- DSNW – Dry, sensitive, no hyperpigmentation, wrinkle-prone
Skin Type 5- OSPT – Oily, sensitive, hyperpigmentation, tight
Skin Type 6- OSNT – Oily, sensitive, no hyperpigmentation, tight
Skin Type 7- OSPW – Oily, sensitive, hyperpigmentation, wrinkle-prone
Skin Type 8- OSNW – Oily, sensitive, no hyperpigmentation, wrinkle-prone
Skin Type 9-OPRT – Oily, resistant, hyperpigmentation, tight
Skin Type 10-ORNT – Oily, resistant, no hyperpigmentation, tight
Skin Type 11- ORPW – Oily, resistant, hyperpigmentation, wrinkle-prone
Skin Type 12- ORNW – Oily, resistant, no hyperpigmentation, wrinkle-prone
Skin Type 13- DRPT – Dry, resistant, hyperpigmentation, tight
Skin Type 14- DRNT – Dry, resistant, no hyperpigmentation, tight
Skin Type 15- DRPW – Dry, resistant, hyperpigmentation, wrinkle-prone
Skin Type 16- DRNW – Dry, resistant, no hyperpigmentation, wrinkle-prone

413 AI-Guided Skin Care
allows treatment of all the barriers to skin health, rather than focusing on only one skin
concern. Here are examples of BST nomenclature and treatment approach:
• DSNW (dry, sensitive, nonpigmented, wrinkle-prone): This skin type needs barrier
repair and soothing products to manage dryness and inflammation, while also
addressing anti-aging concerns. Which sensitive skin subtype this DSNW type has
(acne, rosacea, stinging, or allergic) further dictates which ingredients are appropriate
and which should be avoided. Acne-prone subtypes have very different needs than the
erythematous rosacea-prone subtypes.
• ORPT (oily, resistant, pigmented, tight): This requires products that control sebum
production and prevent and treat hyperpigmentation. The pigmented types will need
both treatment and maintenance regimens to manage hyperpigmentation as it comes
and goes.
BST CODING
Each BST is identified in two ways: a colored and numbered octagon known as the skin
type octagon (Figure 4) and a four-letter code.
For instance, BST 14: DRNT (dry, resistant, nonpigmented, tight) signifies a skin type
that is dry, resistant, evenly toned, and firm. It is represented by a light blue skin type
octagon with a 14. This coding system helps both consumers and skin care professionals
easily identify and remember the specific needs of their skin, while facilitating coding
for machine learning purposes. Data have shown that some people remember the four
letters, while others remember the number or color, so all three components are used when
Figure 4. These are the 16-skin type octagons that correspond to the BSTs. They are trademarked and
cannot be used without written permission to maintain the scientific integrity and proper use of the BSTS.