From the FDA Drug Label
CLINICAL PHARMACOLOGY Topical application of hydroquinone produces a reversible depigmentation of the skin by inhibition of the enzymatic oxidation of tyrosine to 3,4-dihydroxyphenylalanine (dopa) (Denton, C. et al., 1952)1 and suppression of other melanocyte metabolic processes (Jimbow, K. et al., 1974)2. Exposure to sunlight or ultraviolet light will cause repigmentation of bleached areas (Parrish, J.A. et al., 1978)3.
The causes of liver spots are not directly addressed in the provided drug label.
- The label discusses the mechanism of action of hydroquinone in producing depigmentation of the skin.
- It does not provide information on the causes of liver spots or their treatment. The FDA drug label does not answer the question.
From the Research
Liver spots, also known as age spots or solar lentigines, are primarily caused by prolonged sun exposure and can be effectively treated with combination-based treatments or laser-based treatments, as these have shown the greatest frequency of complete response. These spots are flat, brown or black patches that appear on the skin due to excess melanin production, commonly on areas most exposed to the sun like the face, hands, shoulders, and arms. Aging also contributes to their development, as the skin's ability to repair sun damage decreases over time 1.
Causes of Liver Spots
The development of liver spots is strongly related to chronic sun exposure and is associated with photodamage and an increased risk for skin cancer 2. The increased expression of keratins 5 and 10, markers of basal and suprabasal keratinocytes, respectively, in age spots suggests that the increased proliferation of basal keratinocytes combined with the decreased turnover of suprabasal keratinocytes leads to the exaggerated formation of rete ridges in lesional epidermis which in turn disrupts the normal processing of melanin upwards from the basal layer 2.
Treatment Options
Treatment options for liver spots include:
- Topical medications like hydroquinone, retinoids, or vitamin C serums which can gradually fade the spots by reducing melanin production
- Chemical peels containing glycolic acid or salicylic acid can exfoliate the skin and reduce pigmentation
- Laser therapy and intense pulsed light treatments are more aggressive options that target and break down melanin deposits
- Cryotherapy, which freezes the spots with liquid nitrogen, is another effective treatment, although it has substantially lower pooled response rates compared with other treatment modalities 1
- Combination-based treatments have shown the greatest frequency of complete response (65%), followed by laser-based treatments (43%) 1
Prevention
Prevention is crucial - daily use of broad-spectrum sunscreen (SPF 30 or higher), wearing protective clothing, and avoiding peak sun hours can prevent new spots from forming and existing ones from darkening. While liver spots are harmless, any spot that changes in appearance, size, or color should be evaluated by a dermatologist to rule out skin cancer. The safety of hydroquinone, a commonly used lightening agent, has been questioned, and new findings have been reported 3. Emerging therapies for hyperpigmentation include novel formulations such as solid lipid nanocarriers, liposomes, phytochemicals, platelet-rich plasma, and microneedling 4.