October 11, 2019 Why Does Hyperpigmentation Affect Some People And Not Others?
Although hyperpigmentation is extremely common throughout the world, you can’t help but notice that they don’t affect everyone equally. So why is that the case? Let’s find out.
Blame It On The Genes
As with so much when it comes to health, there are some contributing factors to hyperpigmentation regarding our ethnicity and genetics that are out of our control.
The ‘Fitzpatrick Skin Classification’ system is used to describe the different shades of skin present in the population, with very pale skin labeled as ‘type I’ and very dark skin as ‘type VI’. Studies have shown that it is those with skin types in the middle, especially types III and IV that have the highest rates of dark patch development.
The theory is that people with skin type I have pigment cells that are just not very active, even when exposed to things like sunlight. Those with skin type VI, on the other hand, have cells that are already producing the maximum amount of pigment, so they are relatively ‘stable’ in response to extra triggers. This leaves those in the middle with light brown skin who have pigment-producing cells that are pretty active already, but are still capable of becoming extra active in response to the sun or hormonal changes.
In this way, the genes that we have that control our skin color can explain why some of us are more prone to dark patches than others. Let’s take melasma as an example. The role of genetics in melasma is supported by twin-to-twin comparison studies showing very similar rates of dark patches between siblings who share the same genes. Likewise, 40% of those with melasma have a family history of the condition in their direct relatives.
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Let’s Talk About Gender
Aside from ethnicity, your gender may be another reason why you are more at risk for dark patches on your skin. Conditions like melasma that can cause dark patches occur at different rates between men and women. Studies have shown a clear increased risk of melasma in females as compared to males, with estimated frequencies ranging from 9:1 to as high as 35:1.
Pregnancy, Contraceptive Pills, And Other Medications
It is well-known that conditions of skin hyperpigmentation can be triggered by pregnancy or by the use of an oral contraceptive in about 40-50% of female patients. Although melasma associated with pregnancy typically completely disappears (with treatment) within one year of delivery, some dark patches will persist in up to 30% of patients. This happens more often in those using oral contraceptive and in cases with more intense pigmentation. Recurrence is common in subsequent pregnancies and the chances of developing melasma for the first time during any given pregnancy increase with a history of multiple pregnancies.
Importantly, aside from contraceptive pills, there are other types of medications, including antibiotics and blood pressure medications (e.g. minocycline and amiodarone) that can cause reactions in the skin leading to darkening. For this reason, it is important to provide your dermatologist with a full list of all the medications you are taking, including over-the-counter supplements.
Post-Inflammatory Hyperpigmentation (PIH)
As the name suggests, this type of skin darkening occurs after some kind of inflammation to the skin. This is most commonly seen secondary to flares of conditions such as acne and eczema. It is crucial to try to establish what is causing this inflammation and seek treatment for this from a board-certified dermatologist.
No matter what types of products you use to get rid of darkening from PIH, without stopping the inflammation itself, it will be impossible to get meaningful results in terms of skin recovery.
- Achar A, Rathi SK. Melasma: a clinico-epidemiological study of 312 cases. Indian J Dermatol. 2011;56(4):380-382. doi:10.4103/0019-5154.84722 https://www.ncbi.nlm.nih.gov/pubmed/21965843
- Handel AC, Miot LDB, Miot HA. Melasma: a clinical and epidemiological review. An Bras Dermatol. 2014;89(5):771-782. doi:10.1590/abd1806-4841.20143063 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4155956/
- Moin A, Jabery Z, Fallah N. Prevalence and awareness of melasma during pregnancy. Int J Dermatol. 2006;45(3):285-288. doi:10.1111/j.1365-4632.2004.02470.x https://www.researchgate.net/publication/7245797_Prevalence_and_awareness_of_melasma_during_pregnancy
- Resnik S. Melasma induced by oral contraceptive drugs. JAMA. 1967;199(9):601-605. https://www.ncbi.nlm.nih.gov/pubmed/6071249
About the author
Brandon Kirsch, MD, FAAD, is a board-certified dermatologist specializing in clinical drug development and medical innovation. He is the founder of Kirsch Dermatology in Naples, Florida and is also the Chief of Dermatology at the ...