Understanding melasma: Triggers, treatment, and management

A family history of melasma increases your risk of developing the condition, with some studies showing that the occurrence among family members can be as high as 61% . Additionally, people with naturally darker skin tones are more susceptible to melasma because darker skin contains more pigment-producing cells called melanocytes. These cells produce melanin – the pigment responsible for colour. When there’s an overproduction of melanin, it can lead to dark patches. Genetics can also influence your hormone levels, and women with naturally higher oestrogen are more likely to experience melasma.

Ultraviolet (UV) exposure is one of the main causes of skin pigmentation. The main source of UV exposure is the sun, but tanning beds, sun lamps, and nail drying devices all emit UV radiation. UV stimulates melanogenesis, a process in which melanocytes produce melanin. It also indirectly causes skin cells (keratinocytes) to release chemicals that trigger melanin production.

People with darker skin tones are also more susceptible to melasma when exposed to UV. Although melanin helps protect skin, in melasma, UV exposure causes oxidative stress which can result in inflammation, signaling melanocytes to produce melanin uncontrollably.

Female sex hormones, oestrogen and progesterone, can also trigger melasma.

There are three main types of oestrogen: E1, E2, and E3, with E2 (estradiol) being the most common and potent type found in the body.

E2 regulates melanin production and skin pigmentation. It increases melanin production by activating oestrogen receptors in skin cells. This stimulates another process, further promoting melanin production and melanocyte growth.

E1 plays a significant role in melanin formation. It can enhance melanin synthesis by helping activate certain enzymes.

E3 is the main form of oestrogen produced during pregnancy. It supports the growth and maintenance of the placenta and uterus. E3 may also contribute to melanogenesis by increasing oxidative stress. This can damage skin cells and alter melanin synthesis pathways, leading to excess melanin production and hyperpigmentation.

Progesterone causes melasma by binding to specific receptors on melanocytes, resulting in an overproduction of melanin.

Simply having oestrogen and progesterone doesn’t directly cause melasma, but they can increase the skin's susceptibility to it. Melasma usually develops due to a combination of hormonal influences and triggers like UV light, heat, or stress, which can stimulate excess melanin production.

Additionally, hormonal contraception and hormone replacement therapy (HRT) are associated with a higher risk of developing melasma as they alter oestrogen and progesterone levels. Research has found that women with melasma often have higher exposure to oestrogen and progesterone than women without melasma.

High cortisol (stress hormone) levels can be a trigger for melanoma. Chronically high cortisol can cause hormonal imbalances and trigger oxidative stress, which can damage skin cells and melanocytes. This can lead to an overproduction of melanin, resulting in dark patches.