What Is the Glogau Classification of Photoaging?

How to rank the severity of your wrinkles and prevent more with sunscreen

Understand photo aging and treatment. Credit: beautyhealthtips.in / Google Images

The Glogau classification system was developed to objectively measure the severity of photoaging and especially wrinkles. It helps practitioners pick the best procedures to treat photoaging.

Find out where you rank on the system and how to prevent wrinkles with sunscreen. 

Glogau Classification of Photoaging

GroupClassificationTypical AgeDescriptionSkin Characteristics
IMild28-35No wrinklesEarly Photoaging: mild pigment changes, no keratosis, minimal wrinkles, minimal or no makeup
IIModerate35-50Wrinkles in motionEarly to Moderate Photoaging: Early brown spots visible, keratosis palpable but not visible, parallel smile lines begin to appear, wears some foundation
IIIAdvanced50-65Wrinkles at restAdvanced Photoaging: Obvious discolorations, visible capillaries (telangiectasias), visible keratosis, wears heavier foundation always
IVSevere60-75Only wrinklesSevere Photoaging: Yellow-gray skin color, prior skin malignancies, wrinkles throughout - no normal skin, cannot wear makeup because it cakes and cracks


Exposure to ultraviolet light, UVA or UVB, from sunlight accounts for 90 percent of the symptoms of premature skin aging, including wrinkles. The most important skincare product available to prevent wrinkles is sunscreen, but most people do not use sunscreen correctly. Important factors to consider with sunscreen use are the spectrum of UV radiation absorbed, the amount of sunscreen applied and the frequency of application.

UV Radiation

The sun gives off ultraviolet (UV) radiation that we divide into categories based on the wavelength. UVC radiation is absorbed by the atmosphere and does not cause skin damage. UVB radiation affects the outer layer of skin, the epidermis, and is the primary agent responsible for sunburns. UVB does not penetrate glass and the intensity of UVB radiation depends on the time of day and the season. 

UVA radiation penetrates deeper into the skin and works more efficiently.

The intensity of UVA radiation is more constant than UVB without the variations during the day and throughout the year. UVA is also not filtered by glass.

UV Radiation and Wrinkles

Both UVA and UVB radiation cause wrinkles by breaking down collagen, creating free radicals, and inhibiting the natural repair mechanisms of the skin.

A popular classification system of sun sensitivity is the Skin Phototype (SPT) classification. People with skin types I and II are at the highest risk for photoaging effects including wrinkles and skin cancer. The proper use of sunscreen to block both UVA and UVB radiation is an important weapon in the battle against wrinkles.

Sunscreen Ingredients

Sunscreens ingredients can be divided into compounds that physically block radiation or compounds that absorb radiation. The radiation blockers are very effective at reducing the exposure of the skin to both UVA and UVB radiation. Older formulations like zinc oxide are opaque and may be cosmetically unacceptable.

However, a newer formulation of micronized titanium dioxide is not as opaque and provides excellent protection. The radiation absorbing ingredients are differentiated by the type of radiation they absorb - UVA absorbers and UVB absorbers.

Picking the Proper Sunscreen

The SPF measures the amount of UVB absorption, but there is no method of reporting the UVA absorption. The only way to determine if a sunscreen protects against UVA and UVB radiation is to look at the ingredients. A good broad-spectrum sunscreen should have an SPF of at least 15 and contain avobenzone, titanium dioxide or zinc oxide.

Applying Sunscreen Properly

Most people use sunscreen improperly by not applying enough. They apply only 25 to 50 percent of the recommended amount. Sunscreen should be applied liberally enough to all sun-exposed areas that it forms a film when initially applied.

It takes 20-30 minutes for sunscreen to be absorbed by the skin, so it should be applied at least a half an hour before going out in the sun. Sunscreen should also be the last product applied especially on the face since some sunscreens can break down in the presence of water contained in water-based foundations and moisturizers.

Reapplying Sunscreen

Most instructions on sunscreen labels recommend reapplying sunscreen "frequently," but the definition of "frequently" is vague.

A common instruction is to reapply sunscreen after two to four hours in the sun.

However, one study has shown that reapplying sunscreen 20 to 30 minutes after being in the sun is more effective than waiting two hours. It is possible that this time period is more effective because most people do not apply enough sunscreen initially, and this second application approximates the actual amount needed. Sunscreen should also be reapplied after swimming, excessive sweating or toweling.

Daily Sunscreen

Sunscreen should be applied daily. The daily use of a low-SPF sunscreen (15) has been shown to be more effective in preventing skin damage than the intermittent use of a higher SPF sunscreen.

Sunscreen and Insect Repellents

Insect repellents reduce sunscreen's SPF by up to one-third. When using sunscreen and insect repellent together, a higher SPF should be used and reapplied more often.

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